Search

Migration of silver nanoparticles (AgNPs) from food containers (FCs) has been assessed for the first time using a screening method previously validated. Migration was evaluated using water and 3% acetic acid as food simulants (FSs), from 20 to 70 °C at contact times of 2 h and 10 days. Total and migrated Ag were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in the FCs and FSs, respectively. Then, the screening method was validated, and probability of detection (POD) curves were constructed in both FSs to characterize the response to AgNPs. The results provided by the present screening method showed no release of AgNPs. The FSs in contact with FCs were spiked at levels above, inside and below the unreliability region, with a reliability rate (RLR) of 0.90. Asymmetric flow field flow fractionation coupled to inductively coupled plasma mass-spectrometry (AF4-ICP-MS) was used for confirmative analyses.

Magnetic cellulose nanoparticles (MCNPs) coated with 1-butyl-3-methylimidazolium hexafluoro phosphate [C4MIM][PF6] ionic liquid (IL) through electrostatic interactions are proposed for the first time as sorbents in a magnetic solid phase extraction (MSPE) method for the determination of paracetamol (PAR), ibuprofen (IBU), naproxen (NAP) and diclofenac (DIC) in natural waters. The parameters that affect adsorption (dispersive solvent, amount of IL, pH and salt content) and desorption (desorption solvent, type of energy and time) were studied. The values that provided the maximum adsorption efficiency and extraction recovery were selected as optimum conditions for adsorption and desorption, respectively. Under the optimum conditions, the adsorption and desorption of all analytes was simultaneous and quantitative. High performance liquid chromatography (HPLC) with ultra violet (UV) and fluorescence (FL) detector was used after the sample preparation. The precision, expressed as relative standard deviation was between 1.4 and 7.6%. Limits of detection and quantification were in the range 3.2–7.2 μg L− 1 and 11–24 μg L− 1, respectively. Moreover, the proposed method provides enrichment factors from 29.0 to 34.2. Recovery studies on 10 mL of spiked tap, river and dam water samples at 50 and 100 μg L− 1 were carried out. The extraction recoveries were from 85 to 116%, and were in a comparable range regardless of the type of water. The method is simple, rapid, and environmentally friendly.

Dispersive solid phase extraction (DSPE) prior to capillary electrophoresis with ultraviolet and visible detection was used for the first time for the determination of dabrafenib (DB) and trametinib (TT), the main drugs used for the treatment of metastatic melanoma, in serum. Six different magnetic and non-magnetic nanomaterials were evaluated as DSPE sorbents for the extraction and preconcentration of the analytes. The best results were obtained with 4 mg of pristine multi-walled carbon nanotubes in phosphate buffer (pH 12.5; 10 mM). The electrophoretic separation was carried out in a fused silica capillary (30 cm × 75 µm i.d.) at 22 °C in a voltage ramp (8–12 kV) with a background electrolyte consisting of borate buffer (pH 9.2; 25 mM), 37 mM sodium dodecylsulfate, 22% (v/v) acetonitrile and 3% (v/v) methanol. The preconcentration factor achieved was 4, and the limits of detection were 0.012 and 0.008 mg L−1 for DB and TT in serum, respectively. Linearity was observed up to 5 mg/L and precision (n = 7) was below 3% in migration time and 7.8% in peak areas. The present method was applied to six patients under treatment with DB and TT for metastatic melanoma. It requires a less sophisticated instrumentation and lower volume of harmful organic solvents than the methods reported up to present.

A rapid and reliable method based on magnetic solid-phase extraction (MSPE) and ultra-high performance liquid chromatography (UHPLC-FLD) analysis was developed and validated for the quantitative determination of seven polycyclic aromatic hydrocarbons (PAHs) in water samples. Hybrid composites made up of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) were tested as adsorbent materials. The main factors influencing the extraction yields were optimized, namely the amount and type of adsorbent in the adsorption, and the solvent, the type of energy and the time in the desorption step. The selected composite was made up of Fe3O4 and multiwalled (MW)-CNTs. The desorption was carried out with sonication probe and tetrahydrofuran (THF); this solvent makes the method directly compatible with the chromatographic mobile phase and it reduces the analysis time. Under the optimized conditions, the LODs and LOQs achieved were in the range of 0.025–0.73 and 0.04–2.4 ng mL−1, respectively. The calibration curves were linear (R 2 ≥ 0.9936) over the concentration ranges from 1 to 500 ng mL−1. The recoveries of PAHs were from 76.4 ± 1.7 up to 106.5 ± 3.5%. The method was applied to synthetic and real (tap, dam, river and mineral) water samples with different characteristics to evaluate the performance under real conditions.

Magnetic cellulose nanoparticles (MCNPs) were used for the first time as sorbents for stir bar-sorptive dispersive microextraction (SBSDME). The main experimental parameters involved in the SBSDME process that affect extraction (i.e. amount of MCNPs, ionic strength, pH, extraction and back-extraction time) were investigated. The method was applied to the determination of nine polychlorinated biphenyls (PCBs) in fruit juice samples by gas chromatography–mass spectrometry (GC-MS). Under the optimized conditions, a good linearity was obtained in a concentration range of 10–1000 ng mL−1 with determination coefficients over 0.9945. Limits of detection and quantification for all target PCBs were in the range 2.1–54 ng L−1 and 7.0–180 ng L−1, respectively. Intra-day precision ranged from 1.7% to 8.8% and inter-day precision from 3.4% to 9.3% RSD. The enrichment factors of the analytes were from 74.6 to 98.2. The MCNPs can be reused up to 5 times. The method was applied to commercial orange and pineapple juices (n = 5), where concentrations were below the limits of detection. Recoveries from 70.4 to 108.0% were obtained by applying the method for the analysis of spiked fruit juice samples at 1 and 2 ng mL−1 concentration levels. The use of cellulose makes this approach environmentally friendly and the magnetism of the resulting sorbent in conjunction with SBSDME provides ease of handling and saving of time.

Magnetite (Fe3O4) nanoparticles were modified with nanocellulose and are showed to be a useful sorbent for magnetic solid-phase extraction of mercury species. Speciation analysis was performed by using gas chromatography coupled to atomic fluorescence detection (GC-pyro-AFS). The magnetic properties of the sorbent make this approach simple and rapid, and the use of a renewable and biodegradable nanomaterial (nanocellulose) makes it environmentally friendly. The factors that affect adsorption (pH value, amount of nanomaterial, time, volume of sample) and desorption (solvent, time) have been optimized. Both desorption and derivatization of mercury species were performed in a single step. This reduces considerably the sample preparation time. Under the optimized conditions, the limits of detection are 4.0 pg mL−1 for monomethylmercury and 5.6 pg mL−1 for inorganic mercury. The repeatability and reproducibility are satisfactory. The method enables inorganic mercury and monomethylmercury to be simultaneously extracted, with preconcentration factors up to 300. The potential interferences of organic matter and/or co-existing ions were also investigated using synthetic waters. The procedure was applied to the analysis of tap water and river water samples with different characteristics from a mercury polluted area (Almaden, Spain). The extraction recoveries ranged from 81 to 98% regardless of the type of water, which demonstrates the applicability of the method. This is the first time that this kind of sorbent is used for trace metal speciation.

Ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) was used for the first time for the extraction and preconcentration of cortisone and cortisol from human saliva samples. This approach allows the determination of both compounds by liquid chromatography (LC) with ultra-violet/visible (UV/Vis) detection at physiological levels. The IL 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] and methanol (MeOH) were used as extraction and dispersive solvents, respectively. The parameters that affect extraction (ionic strength, pH, amount of IL, volume of dispersive solvent, vortex and centrifugation time) were optimized. Limits of detection were 0.11 (cortisone) and 0.16 μg L−1 (cortisol) and enrichment factors of 5.0 (cortisol) and 6.3 (cortisone) were achieved. Recoveries from 83.3 ± 1.6 to 115.8 ± 3.0% were obtained for the extraction of the target analytes in spiked human saliva samples. Intraday and interday precision, expressed as relative standard deviation, was below 4.2 and 7.8% for cortisone and cortisol, respectively. The method was successfully applied to the determination of cortisone and cortisol in saliva from healthy volunteers (n = 9) in the morning and in the evening. The method is simple, faster, and more environmentally friendly than the current ones.

A new, fast and simple methodology for the determination of total glutathione in earthworms, excellent bioindicators of oxidative stress, using ultra-high performance liquid chromatography with fluorescence detection is presented. Total glutathione could be a biomarker of oxidative stress caused by heavy metals such as mercury. The strategy for the analysis was to transform oxidized glutathione (GSSG) into reduced glutathione (GSH) and then to derivatize total GSH with o-pthalaldehyde to a fluorescent adduct. The analysis was carried out using an Eclipse XDB-C18 (50 mm × 4.6 mm × 1.8 μm) column at 25 °C, and using 100 mmol L−1 phosphate buffer at pH 7.0 and acetonitrile (phosphate buffer–acetonitrile, 85:15, v/v) as the mobile phase at 1.5 mL min−1. The volume injected was 5 μL and the excitation and emission wavelengths were 340 and 420 nm, respectively. Under the optimized conditions, the retention time of the derivatized analyte was as short as 0.536 min, which allows also a very short time between consecutive injections. The instrumental limits of detection and quantification were 1.8 and 5.3 μg L−1 (5.7 and 17.0 nmol L−1) and the calibration curve was linear up to 5 mg L−1 (16.3 μmol L−1). The methodology was also proved to be robust and precise. The methodology was validated using earthworms spiked with GSH, obtaining recoveries close to 100%.

A rapid, economic and environmentally friendly analytical methodology has been implemented for the determination of alpha-, beta-, gamma- and delta-HCH, p,p'-DDT, p,p'-DDD and p,p'-DDE, PCBs congeners #28, #52, #101, #153, #138 and #180 and Hexachlorobenzene in fish oil. 1,2,3,4-Tetrachloronaphtalene was used as internal standard. The sample preparation, consisting of a single step of clean-up and fractionation, took place in a column filled with different layers of neutral and sulphuric acid modified silica. The analytes were eluted by vacuum with of hexane. Significant reduction in terms of solvents, sorbents, and analysis time was achieved in comparison with literature. Gas chromatography coupled to mass spectrometry was used for the separation and determination of the analytes. The instrumental limits of detection were from 0.1 to 1.3ngmL(-1) and the response of the detector was linear up to 200ngmL(-1). The separation proved to be precise (RSD

An analytical methodology was proposed and validated to be applied to the determination of p , p′ -DDT and its metabolites p , p′ -DDE and p , p′ -DDD in fish oil. The analytical procedure presented in this paper involves a single-step clean up process prior to the analysis. A solution of 1,2,3,4-tetrachloronaphtalene was used as internal standard. The analytical technique used was gas chromatography coupled to an electron capture detector. Details on the validation process are provided. The limits of detection ranged from 2.6 to 4.7 pg μL − 1 . The BCR 598 standard reference material (cod liver oil) was used to evaluate the performance of the methodology with satisfactory recoveries for all the compounds. The analytes were determined in three different fish oil pills sold in Spain as a supplementary vitamin support. The sum of p , p′ -DDT and metabolites was from 13.2 to 51.3 ng g − 1 , the dominant compound being p , p′ -DDE.

A simple, rapid and sensitive procedure using solid phase extraction and capillary zone electrophoresis for the determination of propranolol (a beta-blocker) and one of its metabolites, N -desisopropylpropranolol, has been developed and validated. The optimum separation of both analytes was obtained in a 37 cm × 75 μm fused silica capillary using 20 mmol/L phosphate buffer (pH 2.2) as electrolyte, at 25 kV and 30 °C, and hydrodynamic injection for 5 s. Prior to the electrophoretic separation, the samples were cleaned up and concentrated using a C 18 cartridge and then, eluted with methanol, allowing a concentration factor of 30. Good results were obtained in terms of precision, accuracy and linearity. The limits of detection were 28 and 30 μg/L for N -desisopropylpropranolol and propranolol, respectively. Additionally, a robustness test of the method was carried out using the Plackett–Burman fractional factorial model with a matrix of 15 experiments. The presented method has been applied to the determination of both compounds in human urine.

A simple and rapid method has been developed for speciation analysis of inorganic mercury and monomethylmercury (MMHg) in biological tissues. The procedure is based on the quantitative closed-vessel microwave-assisted leaching of mercury from biological samples with an alkaline extractant. The extracted mercury species are ethylated and analysed by capillary gas chromatography coupled to an atomic fluorescence detector via pyrolysis (CGC-pyro-AFS). The coupling between capillary gas chromatography and atomic fluorescence detector was optimized with the aim of minimizing the detection limits and time necessary for the species-selective determination of mercury compounds. The use of closed-vessel microwave-assisted extraction along with no clean-up steps before the ethylation leads to a significant total analysis time decrease with respect to similar procedures. The detection limit was 2 pg for MMHg (as Hg) and 1 pg for inorganic mercury. The method was validated by the analysis of DORM-2 (dogfish muscle) and DOLT-3 (dogfish liver) certified reference materials. The inorganic mercury and methylmercury concentrations found were in good agreement with the certified values. Recovery studies of fish muscle tissue spiked with inorganic mercury and MMHg were done to check the reliability of the method. In all cases satisfactory recoveries (92-105%) were obtained.

A complete analytical procedure, including sample clean-up and a micellar electrokinetic chromatographic method, is presented for the determination of sulfamethoxazole, trimethoprim, and their main metabolites by using 20 mmol L(-1) borate buffer (pH 9.3), 25 mmol L(-1) sodium dodecylsulfate, and 5% v/v acetonitrile as electrolyte. The separation was carried out at 30 kV and 20 degrees C in a fused silica capillary (60.2 cm x 75 microm inner diameter) fitted with a window in the capillary cartridge of 100 x 800 microm. The detector response was linear from the limit of quantification to 3 mg L(-1) for the individual components. The limits of quantification ranged from 0.13 up to 0.24 mg L(-1). The method was applied to human serum, previously spiked at different concentrations of all the analytes, and recoveries between 95% and 108% were obtained.