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This work reported a simple and ultrasensitive label-free method for the detection of hepatitis B virus (HBV) DNA by combining hyperbranched rolling circle amplification (HRCA) with dual-mode detection by inductively coupled plasma mass spectrometry (ICP-MS) and fluorescence using ruthenium complex [Ru(bpy)2dppz]2+ (bpy = 2,2'-bipyridine, dppz = dipyrido [3,2-a:2',3'-c] phenazine) as a dual functional probe. An HBV DNA-initiated HRCA system was designed to realize the highly efficient amplification of HBV DNA with the generation of a mass of dsDNA. Also, the [Ru(bpy)2dppz]2+ probe was then added to intercalate into the dsDNA products, resulting in strong fluorescence recovery of the probe for fluorescence detection. Meanwhile, using a biotin-modified primer in HRCA, the dsDNA-[Ru(bpy)2dppz]2+ complexes could be captured by the avidin-coated 96-well plates, and the captured [Ru(bpy)2dppz]2+ probe was later desorbed by acid for ICP-MS detection. The linear range of the proposed method was 3.5-200 amol L-1 and the limit of detection (LOD) was 1 amol L-1 for ICP-MS detection, while the linear range was 20-500 amol L-1 and the LOD was 9.6 amol L-1 for fluorescence detection. The developed method was applied to human serum sample analysis, and the analytical results coincided very well with those obtained by the real-time polymerase chain reaction (PCR) method. The developed dual-mode label-free detection method was ultrasensitive, simple, and accurate, showing great potential for therapeutic monitoring of HBV infection.

A novel sulfur-containing functional core–shell magnetic porous organic polymer (Fe3O4@BD-TpMA-S-SH MOP) was synthesized as a magnetic solid-phase extraction (MSPE) sorbent for mercury speciation followed by high-performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) detection. The prepared Fe3O4@BD-TpMA-S-SH MOP possessed rich active adsorption sites (S: 25 wt%), high magnetism (39.2 emu g−1) and high adsorption capacity (636, 656, 649 and 366 mg g−1 for Hg2+, methylmercury (MeHg+), ethylmercury (EtHg+) and phenylmercury (PhHg+), respectively). Under the optimal conditions, the limit of detection (LOD) of the developed MSPE-HPLC-ICP-MS method was 0.43, 0.55, 0.69 and 1.1 ng L−1 for Hg2+, MeHg+, EtHg+ and PhHg+, respectively, with a high enrichment factor (EF) in the range of 346–383-fold. The accuracy of the method was validated, and it was successfully applied for trace/ultratrace mercury speciation in environmental water and fish samples. The developed method has high sensitivity, low LOD, high EF, fast adsorption/desorption dynamics and good matrix resistance ability, showing great applicability in real sample analysis with complex sample matrices.

Quantification of multiple disease-related microRNAs (miRNAs) is of great significance for clinical diagnosis. Based on the simultaneous multiple element detection ability of inductively coupled plasma-mass spectrometry (ICP-MS) and good specificity of multicomponent nucleic acid enzymes (MNAzymes), a novel and simple method based on the MNAzyme amplification strategy and lanthanide labeling coupled with ICP-MS detection was proposed for the sensitive and simultaneous detection of three miRNAs (miRNA-21, miRNA-155, and miRNA-10b). Specifically, a probe consisting of streptavidin-modified magnetic beads (SA-MBs) and three DNA substrates labeled with lanthanide tags (159Tb/165Ho/175Lu) was constructed. In the presence of target miRNAs, three pairs of MNAzymes were assembled where each pair was hybridized with the corresponding miRNA, and then the substrates on the SA-MBs were cleaved by the activated MNAzymes, continuously releasing the fragment with lanthanide tags. The released lanthanide tags in the supernatant were collected after magnetic separation and analyzed by ICP-MS, realizing the simultaneous quantification of multiple miRNAs. The correlation of the lanthanide tag signal with the miRNA concentration fitted well in a linear model in the range of 50-1000 pmol L-1 (miRNA-21) and 50-2000 pmol L-1 (miRNA-155 and miRNA-10b). The limits of detection for three miRNAs were 11-20 pmol L-1, with the relative standard deviations of 2.2-2.7%. The recoveries of target miRNAs in the human serum and HepG-2 cells were in the range of 87.2-111% and 93.3-111%, respectively. Overall, the method is ideal for the simultaneous quantification of multiple miRNAs with advantages of low spectral interference, high sensitivity, good selectivity, and strong resistance to the complex matrix.

A spiral stir bar was proposed by using stainless steel spring as the extraction phase carrier to avoid the extraction phase friction and increase the amount of extraction phase for improving extraction efficiency. The extraction phase is filled in the cavity of the spring, resulting in a larger amount of the extraction phase than that conventionally coated on glass stir bar or stainless steel wire. Polyaniline-polydimethylsiloxane sol-gel packed spiral stir bar was prepared and evaluated for the extraction of five estrogens. The prepared spiral stir bar presented good extraction efficiency/preparation reproducibility and long lifetime (more than 150 reused times) for target estrogens. Based on it, a method of spiral stir bar sorptive extraction combined with high performance liquid chromatography coupled with ultra-violet detection was developed for the analysis of trace estrogens in environmental and food samples. The detection limit for five estrogens was 0.11-.31 µg/L, with the enrichment factors of 83.0-118-fold (maximal enrichment factor: 200-fold). The reproducibility evaluated with each estrogen of 5 µg/L (n = 5) was 5.8-8.9%. The method was successfully applied for the determination of estrogens in environmental water and animal-derived food samples.

Heterogeneous immunoassay based on magnetic separation is commonly used in inductively coupled plasma-mass spectrometry (ICP-MS)-based biomedical analysis with elemental labeling. However, the functionalized magnetic beads (MBs) often suffer from non-specific adsorption and random distribution of the functional probes. To overcome these problems, DNA tetrahedron (DT)-functionalized MBs were designed and further conjugated with substrate modified Au NPs (Sub-AuNP). Based on the prepared MB-DT-AuNP probes, an MB-DT based multicomponent nucleic acid enzyme (MNAzyme) system involving Au NPs as the elemental tags was proposed for highly sensitive quantification of miRNA-155 by ICP-MS. Target miRNA would trigger the assembly of MNAzyme, and Sub-AuNP would be cleaved from the MB-DT-AuNP probe, resulting in a cyclic amplification. Single-stranded DNA-functionalized MB (MB-ssDNA)-AuNP probes were prepared as well. Comparatively, the amount of Au NPs grafted onto MB-ssDNA-AuNP probes was higher than that grafted onto MB-DT-AuNP probes. Meanwhile, a higher signal-to-noise ratio was obtained by using MB-DT-AuNP probes over MB-ssDNA-AuNP probes in the MNAzyme system. Under the optimal experimental conditions, the limit of detection for target miRNA obtained by using MB-DT-AuNP probes was 1.15 pmol L-1, improved by 23 times over that obtained by the use of MB-ssDNA-AuNP probes. The proposed MB-DT-MNAzyme-ICP-MS method was applied to the analysis of miRNA-155 in serum samples, and recoveries of 86.7-94.6% were obtained. This method is featured with high sensitivity, good specificity, and simple operation, showing a great application potential in biomedical analysis.

Magnetic porous organic polymers (MOPs) were synthesized by a simple azo reaction, with 1,3,5-tris (4-aminophenoxy) benzene and 1,3,5-trihydroxybenzene as the monomers, and Fe3O4@SiO2 as the core. The preparation process was mild, green and environmental-friendly, avoiding the use of high temperature, metal catalysis and harmful organic reagent. The obtained MOPs were characterized in terms of morphology, pore structure, and magnetism; they exhibited high surface area, good stability/dispersibility, and excellent extraction performance for interest triazole fungicides (TFs). With the prepared MOPs as adsorbent, a method of magnetic solid phase extraction-gas chromatography-flame ionization detection (MSPE-GC-FID) was proposed for the analysis of target TFs in vegetables. After the vegetable samples were chopped and homogenized, acetonitrile was added for ultrasonic extraction, and the extract was diluted for subsequent MSPE process. Different operating conditions affecting the extraction efficiency of TFs, such as extraction time, pH, ionic strength, adsorbent dosage, and volume of sample as well as eluent were carefully optimized. Under the optimized experimental conditions, quantitative extraction could be achieved for target TFs (extraction efficiency of 84.5–90.3%), and the limits of detection were in the rage of 0.12–0.19 μg/L, which is the lowest among the reported GC-FID methods for target TFs presently. The linear range of the method for five TFs was 0.5–200 μg/L with the reproducibility of 2.6–6.8% (n = 7, c = 2 μg/L). The method was assessed by the analysis of target TFs in vegetables, and the recoveries for the spiked cucumber and cabbage were 86.9–117% and 84.7–114% (spiking levels of 80, 400 and 800 μg/kg), respectively, indicating that the matrix effect was negligible in the proposed MSPE procedure. The results show that the developed method of MSPE-GC-FID with MOPs as adsorbent is efficient for the analysis of trace TFs in vegetables.

Increasing use of TiO2 nanoparticles (NPs) leads to an accumulation in environment and a risk to human. In this work, an on-line monolithic capillary microextraction (CME)-inductively coupled plasma mass spectrometry (ICP-MS) method was developed for sensitive determination of TiO2 NPs in environmental water samples. With the presence of citric acid, TiO2 NPs can be selectively adsorbed on the poly(acrylamide)-vinylpyridine-methylene bis-(acrylamide) (poly(AA-VP-Bis)) monolithic column at pH 1, whereas Ti ions cannot be adsorbed. Factors affecting the extraction efficiency such as sample pH, concentration of citric acid and elution conditions were carefully investigated. Under the optimum conditions, a detection limit of 0.63 μg L−1 for TiO2 NPs and a sample throughput of 6 h−1 were achieved. The method can be applied to the determination of TiO2 NPs in the size range of 5–100 nm. The developed method was then applied to the analysis of TiO2 NPs in the East Lake water and Yangtze River water, and recoveries of 84–109% were obtained for spiked samples. Compared with other reported methods for the determination of metal oxide NPs, the developed on-line monolithic CME-ICP-MS has the merits of simple operation, high throughput and no need for digestion before ICP-MS detection.

In this work, magnetic nanoporous carbons (MNPCs) based on Zn/Co-MOFs was synthesized via a facial one-step carbonization method. The prepared MNPCs exhibited high specific surface areas, good chemical stability and high extraction efficiency for interest organophosphorus pesticides (OPPs). The good extraction performance of the MNPCs for interest OPPs can be primarily attributed to π-π interaction and hydrophobic interaction between MNPCs and OPPs. Based on it, MNPCs-based MSPE-GC-FPD method was established for the quantification of five OPPs in fruit samples. The main experimental conditions for MSPE of five target OPPs were investigated systematically and optimized, such as the desorption solvent and volume, extracted volume, ionic strength, extraction time and desorption time. Under the optimal conditions, the limits of detection (LODs, S/N = 3) were found to be in the range of 0.018 (ethion) -0.045 (malathion) μg/L. The linearity was 0.05-100 μg/L for phorate, diazinon, ethion and 0.1-100 μg/L for malathion, fenthion respectively. The reproducibility of the method was in the range of 3.5-9.7%. The recovery experiments were carried out by spiking target OPPs at three concentration levels to validate the accuracy of the proposed method, and the recoveries for target OPPs were 84-116%. The results show that the proposed method in this work can be successfully used to analyze OPPs residue in fruit sample.

Quercetin has been proved to have high medicinal value, and as a type of flavonol, has been found in many plants. A simple, fast and effective detection of quercetin was developed according to the fluorescence enhancement by modified carbon dots (PBA-CDs). PBA-CDs were prepared by connecting phenylboronic acids (PBA) on the surface of carbon dots rich in amino groups. Due to the selective interactions of PBA with the cis-diol groups of quercetin and the additional hydrogen bonds, the intermolecular rotation of quercetin was inhibited, and then the fluorescence significantly increased. The selectivity of this method was proved and the linear ranges were estimated to be 0-28.5 μM with a limit of detection at 28.8 nM. Using this method, the quercetin content in the Ginkgo biloba leaf was measured as 42.28 mg·g-1. In addition, the PBA-CDs hold excellent biocompatibility and have demonstrated their ability to detect quercetin in living cells.

Ti (IV) modified vinyl phosphate magnetic nanoparticles (Fe3 O4 @SiO2 @KH570-PO4 -Ti (IV)) was prepared for simultaneous extraction of multiple arsenic species, followed by high performance liquid chromatography (HPLC) - inductively coupled plasma mass spectrometry (ICP-MS) analysis. Inorganic arsenic (iAs), dimethyl arsenic acid (DMA), monomethyl arsenic acid (MMA), p-amino phenyl arsenic acid (p-ASA), 4-hdroxyphenylarsenic acid (4-OH), phenyl arsenic acid (PAA) and 3-nitro-4-hydroxyphenylarsenic acid (ROX) were investigated as interest analytes. It was found that they were quantitatively adsorbed on Fe3 O4 @SiO2 @KH570-PO4 -Ti (IV) at pH 5, and desorbed completely with 0.1 mol/L sodium hydroxide solution. Enrichment factor of 100-fold was obtained by consuming 100 mL sample solution. Under the optimal conditions, the method combining MSPE with HPLC-ICP-MS presented a linear range of 1-5000 ng/L for seven arsenic species. The limits of detection were 0.39, 0.60, 0.23, 1.85, 0.54, 0.48 and 0.84 ng/L for DMA, MMA, p-ASA, iAs, 4-OH, PAA, ROX, with the relative standard deviations (c = 10 ng/L, n = 7) of 3.6, 3.9, 5.5, 12.4, 6.1, 5.8, 5.0, respectively. The accuracy of the method was validated by analyzing BCR 627 Tuna fish. The application potential of the method was further evaluated by chicken muscle and liver samples. No target arsenic species were detected in these samples, and good recoveries (80.6-123%) were obtained for the spiked samples at low, medium and high concentration levels. This article is protected by copyright. All rights reserved.

Arsenite (As(III)) has been considered as a human carcinogen associated with many human cancers especially skin cancer. Elucidation of the transformed species of As(III) during its metabolism in cells is beneficial for evaluation of its bioeffect. In this work, a hyphenated method of reversed phase ion pair high performance liquid chromatography - inductively coupled plasma mass spectrometry (RP-IP-HPLC-ICP-MS) equipped with collision/reaction cell technology (CCT) was developed for speciation of As(III) and its metabolites (arsenate [As(V)], monomethylarsonic acid [MMA(V)], and dimethylarsinic acid [DMA(V)]) in SCC-7 cells. The developed analytical method exhibits low limits of detection for interest arsenic species in the range of 14-27 ng/L and wide linear range up to four orders of magnitude, providing a sensitive tool for arsenic metabolites analysis and further understanding the metabolism of As(III) in SCC-7 cells. The effect of exposure time, exposure concentrations and elimination time on the arsenic species and total arsenic in SCC-7 cells incubated by As(III) were systematically studied. At low exposure concentrations (5 μM), large proportion of intracellular As(III) transformed to methylated metabolites, and the final methylated metabolite DMA(V), which could not be completely removed from the cells in the elimination process, is considered to play as the primary carcinogen. While at high exposure concentrations (5 μM), most of intracellular As(III) probably bound to biomacromolecules rather than followed biomethylation process, exhibiting different metabolism.

In this work, ethylenediamine modified poly(glycidyl methacrylate-ethylene dimethacrylate)(poly(GMA-EDMA-NH2)) was prepared for highly selective extraction of Se(VI) with high adsorption capacity of 0.825 mg m−1 (530 µm i.d.). Based on it, a novel method of polymer monolithic capillary microextraction (CME) on-line coupling with inductively coupled plasma-mass spectrometry (ICP-MS) was developed for the determination of inorganic selenium species (Se(IV)/Se(VI)) in natural waters. Under the optimized conditions, the analytical performance of the proposed on-line CME-ICP-MS method was evaluated for Se(VI). The limit of detection for Se(VI) was 14.2 ng L−1, and the enrichment factor was 50-fold with the sample throughput of 5 h−1. For Se(IV), the concentration was obtained by subtracting Se(VI) from the total Se(VI) obtained by the proposed method after oxidation of Se(IV) to Se(VI). The accuracy of the method was validated by the analysis of a Certified Reference Materials of GBW(E)080395. The proposed method was applied for the analysis of inorganic selenium species in natural waters with good recoveries. The developed method of monolithic CME-ICP-MS is sensitive, simple and rapid for the analysis of inorganic selenium species in natural waters.

A melamine-based porous organic polymer (mPMF) was synthesized as solid phase extraction (SPE) adsorbent for inline SPE-high performance liquid chromatography (HPLC)-ultraviolet detector (UV) analysis of five phytohormones. Melamine contributed to the rich π-electron and N-containing triazine structure for mPMF, which could form π-π interaction and intermolecular hydrogen bond with COOH containing phytohormones. The synthesized mPMF adsorbent shows extremely high extraction efficiency for five target analytes (>80%) including salicylic acid, indole-3-acetic acid, abscisic acid, 2,4-dichlorophenoxyacetic acid and 1-naphthalene acetic acid. The factors affecting extraction of the target phytohormones were investigated and the optimized experimental conditions were established. The linear range was 0.2–100 μg/L with the limits of detection in the range of 0.06–0.11 μg/L for five target phytohormones. The developed method of mPMF-inline-SPE-HPLC-UV was applied for the analysis of trace target phytohormones in tomato and grape juice samples, and the recovery in the range of 83.1–116% and 87.2–121% was obtained for the spiked tomato and grape juice, respectively. This method has the advantages of high sensitivity and good reproducibility, and it has good application potential for the analysis of phytohormones in fruit samples. Moreover, inline analysis avoided the problems of sample pollution and sample loss, and provided a sample throughput of 5/h.

A dual column packed with a magnetic metal-organic framework composite (MFC) and mercapto-functionalized MFC nanoparticles (MFC-SH) in microfluidic chip channels is described for array chip-based magnetic solid phase microextraction of arsenic species including arsenite [As(III)], arsenate [As(V)], monomethylarsonous acid (MMA) and dimethylarsinic acid (DMA) in SCC-7 cells. At pH 6, the MFC-SH adsorbs As(III) while MFC quantitatively adsorbs As(V), DMA and MMA. The As(III) adsorbed on the MFC-SH can be desorbed with a 2% solution of thiourea in 0.5 M HNO3. The arsenic species MMA, DMA and As(V) are retained on the MFC but can be desorbed by ammonia. A sequential elution strategy was employed to elute MMA, DMA, As(V) and As(III) one by one for subsequent on-line determination by ICP-MS. The limits of detection are 4.8, 6.3, 3.8 and 7.1 ng L−1 for As(V), DMA, MMA and As(III), respectively. The enrichment factors are between 23 and 25, and the throughput is 7 samples per hour. The arsenic species in (spiked) SCC-7 cell samples were analyzed by the online system with adequate recoveries (89–110%).

Double imprinted polymer coated magnetic nanoparticles were fabricated with 4-nm size ZnO nanoparticles acting as the sacrifice templates, which were co-imprinted with template Pb(II) ions. After template removal, abundant transfer pores derived from ZnO nanoparticles were left around the selective adsorption sites derived from Pb(II) ions. The magnetic sorbent exhibit good selectivity, rapid adsorption kinetic and large adsorption capacity for Pb(II). They were used to extract trace Pb(II) followed by graphite furnace atomic absorption spectrometry detection. After the optimization of extraction conditions, following merits are found: (a) rapid extraction (10 min), (b) high preconcentration factor (100 fold), (c) sensitive detection with the detection limit of 9.4 ng·L−1, and (d) low relative standard deviation (6.9%) at a level of 50 ng·L−1 of Pb(II) analyzed 7 times. The method was employed in extraction and quantification of trace Pb in biological and environmental samples with satisfactory recoveries of 87.5–104%.

In this work, poly(1-vinylimidazole-ethyleneglycol dimethacrylate) (poly(VI-EDMA)) monolith coated stir bars were synthesized by one-pot polymerization, and they exhibited higher extraction efficiency and faster extraction dynamics for selected PFAAs than commercial ethylene glycol modified silicone (EG-silicone) and polydimethylsiloxane (PDMS) coated stir bars. Taking eleven PFAAs as target analytes, including C4-C12 perfluoroalkyl carboxylates (PFCAs) and C6, C8 perfluoroalkane sulfonates (PFSAs), a method combining monolith-based stir bar sorptive extraction (SBSE) with high performance liquid chromatography (HPLC) − electrospray tandem mass spectrometry (ESI–MS/MS) was proposed for the determination of multiplex PFAAs in environmental water samples. Under the optimized conditions, low limits of detection (0.06–0.40 ng/L) and wide linear range (0.6–400 ng/L) were obtained for target PFAAs with. The developed method was then applied for the analysis of target PFAAs in environmental water samples, and recoveries of 80.1–117% and 80.3–122% were obtained for target PFAAs in spiked Yangtze River and East Lake water samples respectively.

A switchable hydrophilicity solvent (SHS) based liquid phase microextraction (LPME) method was proposed for the preconcentration of trace Pb (II) and Cd (II) followed by graphite furnace atomic absorption spectrometry (GFAAS) detection. The SHS of protonated triethylamine carbonate (P-TEA-C) was synthesized and applied as the extractant, which is environmentally friendly and low cost. Pb (II) and Cd (II) in ammonium pyrrolidine dithiocarbamate (APDC) complex form was extracted into the triethylamine (TEA) phase by converting P-TEA-C to TEA. The vortex led to the rapid formation of fine droplets of the extractant in the aqueous solution, and enlarged contact surface between both immiscible liquids. The factors affecting the microextraction procedure, including sample pH, APDC concentration, volume of SHS and NaOH, sample volume and matrix effect were investigated. Under the optimal conditions, enrichment factor of 50 was achieved with consumption of 10 mL aqueous sample, and detection limits of 16 and 3.9 ng L−1 were obtained for Pb (II) and Cd (II), respectively. The accuracy of the proposed method was validated by the analysis of Certified Reference Materials of GSBZ50009-88 environmental water, GBW07605 tea and GBW07601(GSH-1) human hair. The method was also successfully applied for determination of Pb (II) and Cd (II) in water, tea and human hair samples.

In this study, poly(1-vinylimidazole) functionalized gold ion imprinted polymer coated magnetic nanoparticles (MNPs@PVIM-Au-IIP) were prepared and characterized. The adsorption behaviors of the prepared MNPs@PVIM-Au-IIP toward gold ions (Au(III)) were studied, it was found that MNPs@PVIM-Au-IIP has good selectivity, high adsorption capacity (185.4 mg g−1) and fast adsorption kinetic for Au(III). Based on it, a new method of ion imprinted magnetic solid phase extraction (II-MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the analysis of trace Au(III) in real samples with complicated matrix. Factors affecting MSPE including sample pH, desorption reagent, elution concentration and volume, elution time, sample volume and adsorption time were optimized. With high enrichment factor of 100-fold, the detection limit of the proposed method is 7.9 ng L−1 for Au(III) with the relative standard deviation of 7.4% (c = 50 ng L−1, n = 7). In order to validate the accuracy of the proposed method, the Certified Reference Material of GBW07293 geological sample (platinpalladium ore) was analyzed, and the determined value was in good agreement with the certified value. The proposed II-MSPE-GFAAS method is simple, fast, selective, sensitive and has been successfully applied in the determination of trace Au in ore, sediment, environmental water and human urine samples with satisfactory results.

Development of multimodal detection technologies for accurate diagnosis of cancer at early stages is in great demand. In this work, we report a novel approach using an aptamer-based dual-functional probe for rapid, sensitive, and specific counting and visualization of MCF-7 cells by inductively coupled plasma–mass spectrometry (ICP-MS) and fluorescence imaging. The probe consists of a recognition unit of aptamer to catch cancer cells specifically, a fluorescent dye (FAM) moiety for fluorescence resonance energy transfer (FRET)-based “off-on” fluorescence imaging as well as gold nanoparticles (Au NPs) tag for both ICP-MS quantification and fluorescence quenching. Due to the signal amplification effect and low spectral interference of Au NPs in ICP-MS, an excellent linearity and sensitivity were achieved. Accordingly, a limit of detection of 81 MCF-7 cells and a relative standard deviation of 5.6% (800 cells, n = 7) were obtained. The dynamic linear range was 2 × 102 to 1.2 × 104 cells, and the recoveries i...

Fe3O4/MOF (metal organic framework)/L-cysteine was synthesized and applied for the removal of Cd(II) from wastewater. The adsorption kinetics and isotherms were investigated, and the results indicated that the adsorption obeyed the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity was calculated to be 248.24 mg g−1. Fe3O4/MOF/L-cysteine was further applied to determine trace amounts of Cd(II) in real water samples using ICP-AES (inductively coupled plasma-atomic emission spectroscopy) based on magnetic solid-phase extraction (MSPE). The determination limit was 10.6 ng mL−1. Additionally, Fe3O4/MOF/L-cysteine can also be used as a fluorescent sensor for “turn-off” detection of Cd(II), and the detection limit was 0.94 ng mL−1.

Cyanuric chloride and 4,4′-diamino-p-terphenyl were adopted as monomers to synthesize poly (4,4′-diamino-p-terphenyl-triazine) (PDT) covalent organic polymer. PDT coated stir bar was prepared and evaluated for the extraction of five phthalate esters (PAEs) with relatively lower logP values (2.7-4.9), including diethyl phthalate, diallyl phthalate, dipropyl phthalate, benzylbutyl phthalate and dibutyl phthalate. It exhibited higher extraction recovery (> 65%) and faster extraction kinetics (50 min vs 240 min) for target PAEs over commercial polydimethylsiloxane coated stir bar. Based on the superior performance, PDT coated stir bar sorptive extraction was combined with high-performance liquid chromatography-diode array detection for trace analysis of five PAEs plasticizers. The limits of detection for target PAEs were 0.04-0.27 μg/L, with the enrichment factors of 54-80-fold. The potential of the method was demonstrated by detecting five target PAEs in Chinese liquor and mineral water samples. No target analytes were detected in Chinese liquor sample, and recoveries of 85.4-109% were obtained for target analytes in spiked liquor samples; trace diethyl phthalate (1.19-2.98 μg/L) and dibutyl phthalate (0.77-0.91 μg/L) were detected in two mineral water samples, with recoveries of 85.4-117% and 87.4-117% respectively in spiked mineral water samples.

In this study, spherical imine-linked covalent organic frameworks (COFs) were fabricated from 2,5-dimethoxybenzene-1,4-dialdehyde (DMTP) and 1,3,5-tris (4-aminophenyl) benzene (TAPB) and named as TAPB-DMTP-COFs. The resulting powders were coated onto bare glass bars via physical-adhesion to obtain TAPB-DMTP-COFs coated stir bars. The self-made stir bars exhibited higher extraction efficiency (74–85%) and faster dynamics (50 min) towards non-steroidal anti-inflammatory drugs (NSAIDs) over ethylene glycol-Silicone (42–68%, 180 min) and polydimethylsiloxane (3–61%, 180 min) coated stir bars. Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), zeta potential and water contact angle were employed to provide a comprehensive understanding of the adsorption mechanism between the coating and analytes. The results displayed that methoxy group worked as an adsorption site helping the adsorption of interest NSAIDs onto the TAPB-DMTP-COFs coating and hydrogen bonds formed between the O atoms and the analytes. Additionally, the adsorption mechanisms possibly also involved π-π interaction and hydrophobic interaction. Moreover, TAPB-DMTP-COFs coated stir bars exhibited good stability and could be reused more than 60 times. Subsequently, a method by combining TAPB-DMTP-COFs coated stir bar sorptive extraction (SBSE) with liquid chromatography (HPLC)-ultraviolet detector (UV) was established for the determination of four NSAIDs in environmental waters. Under the optimized conditions, the established method showed a wide linear range of 0.2/1–500 μg/L for interest NSAIDs, the limits of detection varied from 0.039 to 0.312 μg/L. Yangtze River water, East Lake water and Spring water were subjected to the proposed method, the recoveries in spiked samples were 84.7–104%, 81.2–101% and 82.6–97.6%, respectively.

Polydimethylsiloxane (PDMS)/MIL-100(Fe) coated stir bar was prepared by sol gel technique, and good preparation reproducibility was achieved with relative standard deviations (RSDs) ranging from 2.6% to 7.5% (n=7) and 3.6% to 10.8% (n=7) for bar-to-bar and batch-to-batch, respectively. Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/MIL-100(Fe) stir bar showed better extraction efficiency for target triazines compounds. It also exhibited relatively fast extraction/desorption kinetics and long lifespan. Based on it, a method of PDMS/MIL-100(Fe) coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the determination of six triazines (simazine, atrazine, prometon, ametryn, prometryne and prebane) in environmental water samples. Several parameters affecting SBSE of six target triazines including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.021-0.079μgL-1. The repeatability RSDs were in the range of 2.3-6.3% (n=7, c=0.5μgL-1) and the enrichment factors (EFs) ranged from 51.1 to 102-fold (theoretical EF was 200-fold). The proposed method was applied to the analysis of target triazines in environmental water samples, with recoveries of 98.0-118% and 94.0-107% for spiked East Lake water and local pond water samples, respectively.

In this work, zeolitic imidazolate framework-8 (ZIF-8)/poly (methyl methacrylate-ethyleneglycol dimethacrylate) (MMA-EGDMA) composite monolith was in situ synthesized on stir bar by one-pot polymerization. Compared with the neat monolith, ZIF-8/poly(MMA-EGDMA) composite monolith has larger surface area and pore volume. It also exhibits higher extraction efficiency for target phytohormones than poly(MMA-EGDMA) monolith and commercial polyethylene glycol (PEG) coated stir bar. Based on it, a method of ZIF-8/poly(MMA-EGDMA) monolith coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detection (HPLC-UV) was established for the analysis of five phytohormones in apple and pear samples. The developed method exhibited low limits of detection (0.11-0.51μg/L), wide linear range (0.5-500μg/L) and good recoveries (82.7-111%), which demonstrated good application potential of the ZIF-8/monolith coated stir bar in trace analysis of organic compounds.

As an amplification tool, DNA walker nanomachine exhibits promising potential in the fields of biosensing. To further improve amplification efficiency of DNA walker, a number of cascade amplification systems have been developed, but they still suffer from separated steps and long reaction time. Herein, by combining entropy-driven catalytic (EDC) amplification with DNAzyme reaction, a highly integrated cascade three-dimensional (3D) DNA walker is constructed, which allows the autonomous DNA circuit to be completed in one step. Further combined with element tag and inductively coupled plasma mass spectrometry (ICP-MS) detection, the cascade walker can be used for quantification of miRNA-21. Specifically, the reactant of EDC (WLT complex) and the substrate of DNAzyme (Substrate-Tb) are both fixed on magnetic beads (MBs) to assemble the track of walker. Once cascade DNA walker is triggered by target miRNA, EDC amplification runs first and keeps circulating to liberate many DNAzyme strands. DNAzyme can repeatedly cleave Substrate-Tb with autonomously walking along the substrate on MBs. As a result, a great number of fragments of Substrate-Tb, as output signal, are generated within 1 h, resulting in elemental signal response in ICP-MS and reflecting the amount of miRNA-21. A good linear relationship was obtained with miRNA-21 concentration in the range of 0.02−1 nmol L−1, and the detection limit of 5 pmol L−1 was achieved. The recoveries of miRNA-21 in human serum were 92.0–107 %. The developed method provided a novel idea for constructing highly integrated and efficient cascade DNA walker with ICP-MS strategy for bioanalysis.

A novel adsorbent of magnetic graphene oxide (GO) chemically modified by cysteamine hydrochloride (Fe3O4@SiO2/GO-NH2) through thiol-ene click chemistry reaction was synthesized. The prepared Fe3O4@SiO2/GO-NH2 exhibit selective adsorption to As(V) with high adsorption capacity (52.66 mg g−1). Taking Fe3O4@SiO2/GO-NH2 as the adsorbents, a new method of magnetic solid phase extraction (MSPE) combined with graphite furnace atomic absorption spectrometry (GFAAS) was developed in determining trace-level inorganic arsenic species (As(III) and As(V)) in environmental water and bottled water samples. Various experimental parameters affecting the MSPE have been optimized. Under the optimal experimental parameters, the limit of detection of the established method for As(V) was 1.02 ng L−1, the relative standard deviations were 7.9% (intra-day, c = 50 ng L−1, n = 5) and 4.6% (inter-day, c = 50 ng L−1, n = 7), respectively, and the enrichment factor of the method was 392. GBW08666 and GBW08667 (certified reference material) were analyzed to confirm the accuracy of the method, and the results were matched well with the certified values. The established MSPE-GFAAS method was successfully applied in analyzing trace/ultratrace As(III) and As(V) in real water samples.

Exploitation of efficient adsorbent for analyzing mercury species in complex biological samples is still a big challenge. Herein, a MIL-101 covalently bonded and mercapto functionalized capillary monolithic column was prepared by one-step strategy involving simultaneous initiation of thiol-ene click reaction and radical polymerization. It showed improved specific surface area, hierarchical porous structure, rich sulfhydryl groups and high adsorption capacity for mercury species. It was embedded in the microchannel of microfluidic chip for chip-based array monolithic capillary microextraction (CMCME) of mercury species in cells. Methylmercury (MeHg+) and inorganic Hg (Hg2+) could be simultaneously retained on the prepared column and sequentially eluted; both species could also be simultaneously eluted with 4% thiourea in 0.5 mol L-1 HNO3 solution. Based on it, CMCME was combined with two online detection modes separately, direct inductively coupled plasma mass spectrometry (ICP-MS) detection and high-performance liquid chromatography (HPLC)-ICP-MS detection. The CMCME-ICP-MS system is applicable for the analysis of MeHg+ and Hg2+ with the ratio of lower than 5/1, with the limits of detection (LODs) of 2.6 (MeHg+) and 5.8 (Hg2+) ng L-1 and throughput of 8 h-1. Comparatively, the CMCME-HPLC-ICP-MS system is universal for Hg speciation in cells, providing LODs of 9.7 and 18.9 ng L-1 for MeHg+ and Hg2+ with a throughput of 10 h-1. Both systems exhibited good endurance to complex cell matrix and automated operation. The species analysis of Hg in cells incubated by Hg2+ or MeHg+ was achieved and the demethylation of MeHg+ in HepG2 cells was observed.

Matrix metalloproteinase 2 (MMP2) plays an important role in tumor growth, invasion and metastasis. In this work, a dual-functional magnetic microsphere probe was designed for ICP-MS quantification and fluorescence imaging of MMP2 in cell secretion. In the designed probe, a NH2-peptide (-FAM)-biotin was used as a bridge for the combination of carboxylated magnetic beads (MBs-COOH) and streptavidin functionalized gold nanoparticle (Au NP-SA). Initially, the fluorescence of FAM was quenched by Au NP. Since the NH2-peptide (-FAM)-biotin had a MMP2-specifically recognized sequence, the peptide was specifically cleaved in the presence of MMP2, thus releasing Au NP for the ICP-MS quantification of MMP2 and turning on the fluorescence of FAM for the fluorescence imaging of MMP2. Under the optimal experimental conditions, a linear range of 0.05–50 ng mL−1 and a limit of detection of 0.02 ng mL−1 were obtained for MMP2. The relative standard deviation (n = 7, c = 0.1 ng mL−1) of the proposed method was 5.4%. With good sensitivity and good accuracy, the proposed method realized the quantification and imaging of MMP2 in A549 cell secretion. The proposed method was applied to monitor the expression of MMP2 in the A549 cell secretion under the stimulation of Cd2+, providing a new detection strategy in the study of MMP2-related life process.

In this work, di(2-ethylhexyl)phosphoric acid (P204) grafted magnetic nanoparticles were synthesized by fabricating P204 onto Fe 3 O 4 @TiO 2 nanoparticles based on Lewis acid-base interaction between Ti and phosphate group under weakly acidic condition. The prepared Fe 3 O 4 @TiO 2 @P204 nanoparticles exhibited excellent selectivity for rare earth elements, and good anti-interference ability. Based on it, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for fast preconcentration and determination of trace rare earth elements in environmental samples. Under the optimal conditions, the detection limits of rare earth elements were in the range of 0.01 (Tm)–0.12 (Nd) ng L − 1 with an enrichment factor of 100-fold, and the relative standard deviations ranged from 4.9 (Pr) to 10.7% (Er). The proposed method was successfully applied to the determination of rare earth elements in environmental samples, including river water, lake water, seawater and sediment.

Trace heavy metals have great impact on biological system; therefore, it is essential to develop suitable analytical methods for the determination of trace heavy metals in biological samples to elucidate their biochemical and physiological functions in organisms. Herein, we presented a chip-based array monolithic microextraction system and combined it with inductively coupled plasma mass spectrometry (ICPMS) for online analysis of trace Hg, Pb, and Bi in real-world biological samples. Six ethylenediamine modified poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (poly(GMA-co-EDMA-NH2)) capillary monolithic columns were embedded parallelly in microchannels of a microfluidic chip for array monolithic microextraction. Various parameters affecting the chip-based array monolithic microextraction of target metals were investigated. The sample throughput of the proposed method was 16 h–1, with the limits of detection for Hg, Pb, and Bi of 23, 12, and 13 ng L–1, respectively. The developed method was ...

We report a sensitive, selective, simple, and reliable magnetic immunoassay protocol for detection and imaging of HepG2 cells. After being captured by Cs-doped multicore magnetic nanoparticles (MMNPs), HepG2 cells were labeled by CdSe/ZnS quantum dots (QDs), which could be visualized by fluorescence imaging using the photoluminescence property of QDs, and subsequently, they can be counted by inductively coupled plasma mass spectrometry (ICP-MS) with Cd/Cs as elemental tag. Because of the superior photoluminescence properties and the large quantities of detectable Cd atoms contained in the QDs core, QDs play a dual function role in this assay, making the method easier and more comprehensive than other similar approaches. Under the optimal conditions, the limit of detection of 61 HepG2 cells and the relative standard deviation of 5.4% (800 HepG2 cells, n = 7) were obtained. The linear range was 200-30 000 cells, and the recoveries in human whole blood were in the range of 86-104%. The proposed method enables us not only to count but also to see the cancer cells with the same labeling process, opening a promising avenue for research and clinical application.

Monoliths composed of poly(1-vinylimidazole-ethylene glycol dimethacrylate), referred to as poly(VI-EGDMA), were modified with imidazole groups and used in capillary microextraction (CME) of trace levels of Co(II), Ni(II) and Cd(II) ions from human urine samples. The effects of sample pH, sample flow rate, sample volume, elution conditions and potentially interfering ions were investigated. Under the optimized conditions, the limits of detection (3σ) are 0.6 ng L−1 for Co(II), 6.4 ng L−1 for Ni(II) and 0.7 ng L−1 for Cd(II), with the relative standard deviations of 1.8 (Co), 4.2 (Ni) and 2.2% (Cd). A Certified Reference Material (ZK018–2, lyophilized human urine) was analyzed to validate the method, and the values found were in good agreement with the certified ones. The method was successfully applied to the analysis of trace Co, Ni and Cd in human urine samples, and the recoveries for spiked samples were in the range from 89% to 105%. The one-step preparation of monolithic material in our perception is an attractive feature for this material which also excels by good extraction performance in that it possesses abundant adsorption sites, good stability and a long lifetime.

In this work, iminodiacetic acid (IDA) functionalized magnetic nanoparticles (Fe3O4@SiO2@IDA) were prepared and the adsorption behavior of Cr(III)/(VI) on them was investigated. It was found that both Cr(III) and Cr(VI) could be quantitatively retained on Fe3O4@SiO2@IDA in the pH range of 2.5–3.5, while only Cr(III) could be adsorbed in the pH range of 4.0–9.0. Based on this, a new approach of magnetic solid phase extraction (MSPE) combined with graphite furnace atomic absorption spectrometry (GFAAS) was proposed for the speciation of trace Cr(III) and Cr(VI). Total Cr and Cr(III) were adsorbed on Fe3O4@SiO2@IDA under pH 3 and 5, respectively, followed by elution with 1.5 mol L−1 HNO3. And the concentration of Cr(VI) was calculated by subtracting Cr(III) from the total Cr. Factors affecting MSPE (pH of sample solution, concentration and volume of desorption reagent, desorption time, extraction time, sample volume) were investigated and the optimized conditions were achieved. With an enrichment factor of 100-fold, the detection limits of the proposed method were 9.1 and 12.8 ng L−1 for Cr(III) and total Cr with the relative standard deviations (RSDs) of 4.8 and 5.2% (c = 50 ng L−1, n = 7), respectively. In order to validate the accuracy of the proposed method, a certified reference material of GSBZ50009-88 environmental water was analyzed, and the determined value was in good agreement with the certified value. The proposed MSPE-GFAAS method is simple, fast, selective and sensitive for the speciation of trace Cr without any oxidation or reduction process. It has been applied in the speciation of trace Cr in natural water samples with satisfactory results.

A novel magnetic sulfur-doped porous carbon (MSPC) was fabricated via a simple one-step carbonization of a mixture of sucrose, basic magnesium sulfate whiskers and Fe3O4@SiO2 nanoparticles. Due to the high S content, the prepared MSPC possessed high adsorption capacity for Hg2+ (343 mg g−1) with good selectivity. Based on this, a method coupling magnetic solid phase extraction (MSPE) with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace Hg2+ in environmental water samples. Various parameters such as pH, desorption solvent and its concentration, desorption volume and time, sample volume, and adsorption time that affect the determination have been optimized. Under the optimal conditions, a high enrichment factor of 100-fold was obtained, the limit of detection (LOD) was found to be 0.52 pg mL−1 with a relative standard deviation (c = 10 pg mL−1, n = 7) of 7.1%, and a good linearity was obtained within the concentration range of 2–5000 pg mL−1 for Hg2+. Besides, the proposed method has very fast adsorption/desorption kinetics, target Hg2+ could be rapidly adsorbed on the prepared MSPC in 2 min and desorbed from the MSPC in 2 min with the assistance of a permanent magnet. Therefore, the proposed method of MSPE-ICP-MS exhibits good application potential in the determination of trace Hg2+ in environmental water samples.

Protein phosphorylation analysis is important for understanding cell regulations. Mass spectrometry (MS) is a powerful technique for peptide phosphorylation analysis. However, quantification of low abundance phosphoproteins in a complex mixture of proteins is still a challenge. Here we report the development of hollow fiber (HF) supported TiO2 monolithic microextraction combined with capillary high performance liquid chromatography (capHPLC)-inductively coupled plasma-collision reaction cell (ICP-CRC)-MS for the absolute quantification of phosphopeptides. The membrane pores (∼200 nm) of the HF effectively carry more TiO2 on its surface to enhance the adherence of the TiO2 monolith with the HF. By using β-casein as a model phosphorylated protein, we optimized the HF-supported TiO2 monolithic microextraction towards phosphopeptides. Under the optimal conditions, a 100-fold enrichment factor was obtained and the monoliths can be reused 40 times. By monitoring 31P16O with O2 as a reaction gas in the CRC, polyatomic mass interference at m/z 31 is avoided and a low detection limit (2.9 nM) of phosphorus is achieved. The method of HF-supported TiO2 monolithic microextraction-capHPLC-ICP-MS provided the detection limit for phosphopeptides at the nM level. The proposed method was applied to the quantification of phosphopeptides in milk and milk powder samples.

In this work, a novel method of Au nanoparticles (NPs) modified polymer monolithic capillary microextraction (CME) on-line coupling with inductively coupled plasma-mass spectrometry (ICP-MS) was developed for the determination of trace rare earth elements (REEs) in environmental and biological samples. The poly(glycidyl methacrylate-ethylene dimethacrylate) monolithic capillary was prepared, functionalized with thiol ligands for the attaching of Au NPs, and then modified with mercaptosuccinic acid to provide massive carboxyl groups which have high affinity to REEs. With the modification of Au NPs, the adsorption capacity of the monolith towards target REEs has been improved by 3 to 6.5 times. Under the optimized conditions, the limits of detection of the developed method for REEs were in the range of 0.16 (Tb)–0.85 (Gd) ng L− 1. The enrichment factor was 25-fold with the sample throughput of 10 h− 1. And the relative standard deviations were between 2.7 (Lu) and 9.8% (Dy) (c = 10 ng L− 1, n = 9). The accuracy of the method was validated by the analysis of a standard stock solution of GSB04-1789-2004 and a Certified Reference Material of GBW07301a stream sediment. The proposed method was applied for the analysis of trace REEs in seawater samples as well as human whole blood with good recoveries. The prepared monolith is featured with strong anti-interference ability, superior adsorption capacity as well as long lifespan, and the developed monolithic CME-ICP-MS is sensitive, simple and rapid for the analysis of trace/ultra-trace REEs in environmental and biological samples with complex matrix.

Sensitive detection of circulating tumor cells (CTCs) is of great significance in the early detection of cancer and cancer metastasis. This work reported an efficient, specific, and sensitive immunoassay protocol for detection of tumor cells by using inductively coupled plasma mass spectrometry (ICP-MS) with gold nanoparticles (AuNPs) labeling and hybridization chain reaction (HCR) amplification. In the established approach, antibodies against epithelial cell adhesion molecule (anti-EpCAM) conjugated magnetic beads (MBs) were used for selective capture of tumor cells from peripheral blood, aptamer was applied for the recognition of captured tumor cells, and AuNPs labeled DNA concatamer was used as the signal probe for tumor cell labeling and ICP-MS detection. Due to the dual amplification effect of AuNPs and HCR, the limit of detection of this ICP-MS based method for HepG2 cells was as low as 15 cells, and the linear range was 40-8000 cells with the relative standard deviation for seven replicate detections of 200 HepG2 cells was 8.7%. Furthermore, the applicability of the method for the analysis of peripheral blood samples was demonstrated by the spiking tests. The established method was highly specific and sensitive for the detection of HepG2 cells, and has a good application potential in clinical diagnosis.

Phosphorylated p53 proteins are biomarkers with clinical utility for early diagnosis of cancer, but difficult to quantify. An inductively coupled plasma mass spectrometry (ICP-MS) based immunoassay is described here that uses uniform lanthanide nanoparticles (NPs) as elemental tags for the simultaneous determination of two phosphorylated p53 proteins. Apoferritin templated europium (Eu) phosphate (AFEP) NPs and apoferritin templated lutetium (Lu) phosphate (AFLP) NPs with 8 nm in diameter were used to label two phosphorylated p53 proteins at serine 15 and serine 392 sites (p-p5315 and p-p53392), respectively. The assay has a sandwich format, and p-p5315 and p-p53392 were first captured and then recognized by AFEP and AFLP NPs labelled antibodies, respectively. The Eu and Lu were then released from the immune complexes under acidic condition for ICP-MS measurement. The limits of detection for p-p5315 and p-p53392 are 200 and 20 pg·mL−1, with linear ranges of 0.5–20 and 0.05–20 ng·mL−1, respectively. The method was further applied to study the response of p-p5315 and p-p53392 in SCC-7 cells exposed to the natural carcinogen arsenite. A significant up-regulation of p-p5315 and p-p53392 can be observed when cells were exposed to arsenite at 5 μmol·L−1 level for 24 h.

Herein, polyaniline functionalized magnetic nanoparticles (MNPs) were prepared and investigated as the adsorbents for the separation and enrichment of inorganic selenium and tellurium species. The prepared Fe3O4@SiO2@polyaniline (PANI) MNPs presents selective adsorption performance for SeIV and TeIV, along with fast adsorption and desorption dynamics. Based on it, a method combining magnetic solid phase extraction (MSPE) with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the simultaneous speciation of inorganic Se and Te in environmental waters. The adsorption mechanism was investigated preliminarily. Various parameters affecting Fe3O4@SiO2@PANI MSPE of SeIV and TeIV were investigated. Under the optimized conditions, the limits of detection (3σ) for SeIV and TeIV were found to be 5.3 and 1.2 pg mL−1, with the relative standard deviations (cSe(IV) = 100 pg mL−1, cTe(IV) = 10 pg mL−1, n = 7) of 3.8 and 8.0%, respectively. The enrichment factor of the proposed method is 100-fold. The proposed method was successfully applied to the speciation of inorganic Se and Te in environmental water samples. The developed MSPE-ICP-MS method possesses the advantages of low cost, high enrichment factor, rapid operation and can simultaneously analyze inorganic Se and Te species in real-world samples.

A method is described for counting circulating tumor cells (CTCs). It is making use of inductively coupled plasma mass spectrometry (ICP-MS) along with a dual amplification strategy by combining rolling circle amplification (RCA) and gold nanoparticle (Au NP) labeling. HepG2 cells, as a representative CTC line, were captured by anti-epithelial cellular adhesion molecule (EpCAM) immobilized on a microplate, then specifically labeled with biotinylated anti-asialoglycoprotein receptor (ASGPR). Taking streptavidin (SA) as the bridge, the biotinylated RCA primer was conjugated to HepG2 cells. When the RCA reaction was triggered, long ssDNA with tandem repeats generated on the cell surface. Then, Au NP functionalized detection DNA (signal probes) was added to hybridize with the ssDNA. After removing the redundant signal probes, Au NPs conjugated on target HepG2 cells were subjected to ICP-MS detection. By adopting such a dual amplification strategy, a 756-fold improvement in sensitivity is accomplished compared to the method involving only Au NP labeling without RCA. The limit of detection is as low as 3 HepG2 cells (15 cell mL−1) which is the lowest LOD in ICP-MS based methods for cell counting. Besides, the method provides good selectivity, a wide linear range of 10–1000 HepG2 cells (50–5000 cells mL−1), and relative standard deviations of 6.3% (n = 7; 50 HepG2 cells (250 cells mL−1)). The method was successfully applied to HepG2 cell counting in spiked human blood samples and gave good recoveries.

A novel method by hyphenating chip-based array ion-imprinted monolithic microextraction with inductively coupled plasma mass spectrometry (ICP-MS) was proposed for the online analysis of trace Gd in biological samples in this work. The poly(γ-methacryloxypropyltrimethoxysilane@Gd3+-surface ion-imprinted polymer) [poly(γ-MAPS@Gd3+-SIIP)] monolithic capillary was prepared via in situ polymerization on the vinyl-modified surface of poly(γ-MAPS) using Eu3+ as the mimic template. The prepared ion-imprinted monolithic capillary possessed higher selectivity and adsorption capacity to Gd3+ than the non-imprinted monolithic capillary. Eight poly(γ-MAPS@Gd3+-SIIP) monolithic capillaries were embedded in the channels of a microfluidic chip to fabricate a chip-based array microextraction device. Factors affecting the selectivity of the prepared ion-imprinted monolithic capillary including imprinted time and the composition of the prepolymerization solution, and extraction conditions for the fabricated chip-based array ion-imprinted monolithic capillary microextraction platform were optimized. A sample throughput of 18 h−1 was achieved along with a low detection limit of 1.27 ng L−1 for Gd3+. The proposed chip-based array poly(γ-MAPS@Gd3+-SIIP) monolithic microextraction-ICP-MS method was used for the analysis of trace Gd in human urine and serum, and the recovery for spiking experiments was in the range of 88.1–96.7%. The developed integrated analysis platform possesses good interference resistance, high automation, high sensitivity and low consumption of the sample/agent, which makes it very suitable for the analysis of trace elements in complicated biological samples.

In this work, a hydroxyl-containing porous organic framework (HC-POF) was prepared by a simple solvothermal reaction with 1,4-phthalaldehyde and phloroglucinol as monomers. Sol-gel method was used to coat HC-POF on the glass stir bar. The prepared HC-POF coated stir bar shows better extraction performance for six triazole fungicides (TFs) compared to commercial polydimethylsiloxane and ethylene glycol-silicone coated stir bars. Fourier transform infrared Spectrometry and X-ray photoelectron Spectrometry were used to explore interactions between HC-POF coating and TFs. It is assumed that the coating mainly adsorbs TFs through π-π interactions, hydrogen bonding and hydrophobic interactions. Based on this fact, a new method of HC-POF coated stir bar sorptive extraction combined with high performance liquid chromatography-diode array detector was developed for the determination of six TFs in grape and cabbage samples. A series of extraction and desorption conditions were carefully optimized, including salt concentration, sample solution pH, stirring rate and desorption solvent. Under the optimized experimental conditions, the proposed method displayed limits of detection in the range of 0.022 -0.071 μg L-1, which is the lowest among the reported SBSE methods for target TFs analysis. The linear range for six TFs was 0.1/0.2-500 μg L-1 and the recoveries for the spiked grape and cabbage were 81.0-109% and 80.7-111%, respectively.

In this work, the metal-organic frameworks (MOFs), MIL-101-Cr-NH2 was synthesized via a direct hydrothermal method, and a polydimethylsiloxane (PDMS)/MIL-101-Cr-NH2 coated stir bar was prepared by sol-gel technique. Good reproducibility was obtained for the preparation of PDMS/MIL-101-Cr-NH2 coated stir bar with the relative standard deviations (RSDs) ranging from 3.7 to 5.2% (n=7) in one batch, and from 5.4 to 9.2% (n=7) among different batches. With the high surface area and rich benzene ring structure of MIL-101-Cr-NH2, the prepared PDMS/MIL-101-Cr-NH2 coated stir bar presented higher extraction efficiency for target organophosphorus pesticides (OPPs, including phorate, diazinon, malathion, fenthion, quinalphos and ethion) over PDMS coated stir bar. Based on it, a new method of PDMS/MIL-101-Cr-NH2 coated stir bar sorptive extraction (SBSE) coupled to gas chromatography-flame photometric detection (GC-FPD) was proposed for the determination of six OPPs in environmental water samples. The operation parameters affecting the extraction efficiency of SBSE, including extraction time, stirring rate, desorption time and ionic strength, were investigated. Under the optimal conditions, the limits of detection (S/N=3) were found to be in the range of 0.043-0.085μgL(-1) for the six target OPPs, and the linear range was 0.5-100μgL(-1) for malathion and 0.2-100μgL(-1) for other five OPPs. The RSDs of the proposed method evaluated at 1µgL(-1) for each OPP were in the range of 5.9-8.7% (intra-day, n=7) and 6.1-10.7% (inter-day, n=5), respectively. The enrichment factors were varied from 110 to 151-fold (theoretical enrichment factor was 200-fold). The proposed method was applied to the analysis of OPPs in East Lake and pond water samples with recoveries in the range of 89.3-115% and 80.0-113% for the spiked East Lake and pond water samples, respectively.

A new method by coupling surfactant assisted dispersive liquid liquid microextraction (SA-DLLME) with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was proposed for the analysis of gold nanoparticles (AuNPs) in environmental water samples. Effective separation of AuNPs from ionic gold species was achieved by using sodium thiosulphate as a complexing agent. Various experimental parameters affecting SA-DLLME of AuNPs, such as the organic solvent, organic solvent volume, pH of the sample, the kind of surfactant, surfactant concentration, vortex time, speed of centrifugation, centrifugation time, and different coating as well as sizes of AuNPs were investigated carefully. Furthermore, the interference of coexisting ions, dissolved organic matter (DOM) and other metal nanoparticles (NPs) were studied. Under the optimal conditions, a detection limit of 2.2 ng L− 1 and an enrichment factor of 152-fold was achieved for AuNPs, and the original morphology of the AuNPs could be maintained during the extraction process. The developed method was successfully applied for the analysis of AuNPs in environmental water samples, including tap water, the East Lake water, and the Yangtze River water, with recoveries in the range of 89.6–102%. Compared with the established methods for metal NPs analysis, the proposed method has the merits of simple and fast operation, low detection limit, high selectivity, good tolerance to the sample matrix and no digestion or dilution required. It provides an efficient quantification methodology for monitoring AuNPs' pollution in the environmental water and evaluating its toxicity.

In this paper, a method of graphene oxide (GO)-TiO2 composite solid phase extraction followed by graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the speciation of inorganic selenium in environmental waters. The adsorption behavior of inorganic Se(IV) and Se(VI) on the GO-TiO2(1:1) composite was investigated. It was found that Se(IV) was quantitatively retained on the GO-TiO2 composites within a wide pH range of 0.5-10, while Se(VI) was quantitatively adsorbed on GO-TiO2(1:1) composite at pH 0.5-2, and no obvious adsorption of Se(VI) within the pH range of 4-10 was found. By selecting pH 6.0, Se(IV) could be easily determined. After reduction of Se(VI), total Se was determined by the proposed method, and Se(VI) was calculated as the difference between the total Se and Se(IV). The factors affecting the separation/preconcentration of Se(IV) and Se(VI) were studied. Under the optimum conditions, the isothermal adsorption of Se(IV) on the GO-TiO2(1:1) composite fitted Langmuir model; a linear range over 0.1-12ngmL(-1) was obtained. The limit of detection (LOD) and precision of the method for Se(IV) was 0.04ngmL(-1) and 9.4% (cSe(IV)=0.5ngmL(-1), n=7), respectively. In order to verify the accuracy of the method, a standard water sample (GSBZ50031-94) was analyzed, and the determined value was in a good agreement to the certified value. The established method was applied to inorganic Se speciation in environmental water samples and the recovery of 87.4-102% was obtained for the spiked samples.

Due to the high selectivity and stability, molecularly imprinted polymers (MIPs) have been successfully applied in stir bar sorptive extraction (SBSE) as a special coating to improve the selective extraction capability for target analytes. However, traditional MIPs usually suffer from incompatibility in aqueous media and low adsorption capacity, which limit the application of MIP coated stir bar in aqueous samples. To solve these problems, a water-compatible graphene oxides (GO)/MIP composite coated stir bar was prepared in this work by in situ polymerization. The prepared water-compatible GO/MIP coated stir bar presented good mechanical strength and chemical stability, and its recognition ability in aqueous samples was improved due to the polymerization of MIP in water environment, the adsorption capacity for target analytes was also increased by the addition of GO in MIP pre-polymer solution. Based on it, a method of water-compatible GO/MIP coated stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet detector (HPLV-UV) was proposed for the analysis of propranolol (PRO) in aqueous solution. The influencing factors of SBSE, such as sample pH, salt effect, stirring rate, extraction time, desorption solvent and desorption time, were optimized, and the analytical performance of the developed SBSE-HPLC-UV method was evaluated under the optimized conditions. The limit of detection (LOD) of the proposed method for PRO was about 0.37 μg L(-1), and the enrichment factor (EF) was 59.7-fold (theoretical EF was 100-fold). The reproducibility was also investigated at concentrations of 5 μg L(-1) and the relative standard deviation (RSD) was found to be 7.3% (n=7). The proposed method of GO/MIP coating-SBSE-HPLC-UV was successfully applied for the assay of the interested PRO drug in urine samples, and further extended to the investigation of the excretion of the drugs by monitoring the variation of the concentration of PRO in urine within 10h after drug-taking.

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively.

A novel adsorbent of multi-wall carbon nanotubes (MWCNTs) chemically modified silica (MWCNTs-silica) was synthesised and employed as the adsorbent material for solid-phase extraction (SPE) of trace Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V) in environmental water samples followed by inductively coupled plasma optical emission spectrometry detection. This material inherits the advantages of nanomaterial MWCNTs and conventional silica with dual functional groups (–NH2 and –COOH), and avoid the problem of nanomaterial in SPE, such as high pressure. The factors affecting the separation and preconcentration of target elements such as pH, sample flow rate and volume, eluent concentration and volume were investigated. Under the optimised conditions, the detection limits for Zn(II), Cu(II), Cd(II), Cr(III), V(V) and As(V) were 0.27, 0.11, 0.45, 0.91, 0.55 and 0.67 μg L−1 with the relative standard deviations of 3.1, 5.9, 4.1, 4.0, 7.3 and 8.6% (c = 10 μg L−1, n = 7), respectively. The adsorption capa...

Microfluidic devices provide a potential platform that can specialize in miniaturization, integration and automation. In this study, we prepared ethanediamine modified poly glycidyl methacrylate trimethylol propane triacrylate monolithic columns (poly (GMA-co-TRIM-NH2)) in a microfluidic chip channel and established a novel method by combining chip-based poly (GMA-co-TRIM-NH2) monolithic microextraction with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of bismuth in cell samples. Various factors affecting chip-based monolithic microextraction of bismuth were investigated. Under the optimized conditions, the limit of detection was 0.21 ng mL−1 and the relative standard deviation for bismuth was 6.0% (c = 5 ng mL−1, n = 7). The method was successfully applied to the analysis of HepG2 cells incubated with bismuth. With consumption of ∼600 cells, the average amount of bismuth was determined to be at the sub picogram level in a single cell. The prepared chip-based poly (GMA-co-TRIM-NH2) monolithic column had a high-surface area and exhibited high extraction efficiency towards bismuth. The proposed chip-based monolithic microextraction method combined with ICP-MS provides a novel strategy for the analysis of trace metals in cells.

In this work, γ-mercaptopropyltrimethoxysilane (γ-MPTS) modified Fe3O4@SiO2 magnetic nanoparticles (MNPs) was successfully prepared, and characterized by Fourier transform infrared spectrometer (FT-IR), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM). The sorption performance of the prepared Fe3O4@SiO2@γ-MPTS MNPs towards methylmercury (CH3Hg(+)) and inorganic mercury (Hg(2+)) was investigated. It was found that CH3Hg(+) and Hg(2+) could be simultaneously retained on the prepared Fe3O4@SiO2@γ-MPTS MNPs, and the quantitative elution of CH3Hg(+) and total mercury (THg) was achieved by using 1.5 mol L(-1) HCl containing 0.01% and 3% thiourea (m/v), respectively. And the levels of Hg(2+) were obtained by subtracting CH3Hg(+) from THg. Based on the above facts, a method of magnetic solid phase extraction (MSPE) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the speciation of CH3Hg(+) and Hg(2+). Various experimental parameters affecting MSPE of CH3Hg(+) and Hg(2+) such as pH, eluent, sample volume, and co-existing ions have been studied. Under the optimized conditions, the limits of detection (LODs) for CH3Hg(+) and THg were 1.6 and 1.9 ng L(-1), respectively. The accuracy of the proposed method was validated by analysis of a Certified Reference Material NRCC DORM-2 dogfish muscle, and the determined values are in good agreement with the certified values. The proposed method has also been successfully applied for the speciation of CH3Hg(+) and Hg(2+) in environmental water and human hair samples.