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Owing to the large molecular sizes of polycyclic aromatic hydrocarbons, their adsorption using microporous sorbents leads to a low adsorption capacity. Here, to increase the extraction capacity and detection sensitivity of polycyclic aromatic hydrocarbons, a highly efficient dispersive micro solid-phase extraction method was developed based on a stable mesoporous metal-organic framework named Jilin University China 48. Jilin University China 48 is a super hybrid with large one-dimensional hexagonal nanotube-like channels of 24.5 × 27.9 A, which exhibits high potential to be an efficient sorbent of dispersive micro solid-phase extraction to adsorb polycyclic aromatic hydrocarbons. By combining with high-performance liquid chromatography, a sensitive method was developed for the determination of seven polycyclic aromatic hydrocarbons. The synthesized Jilin University China 48 exhibited excellent characteristics of stability, good morphology, large surface area, and open adsorption sites. Under the optimized extraction conditions, better extraction results were obtained than that of other methods reported previously. The proposed method exhibited high sensitivity with the limit of detections in the range of 0.021-0.13 ng/mL, good linearity in the range of 0.068-50 ng/mL with related coefficients of >0.9988, satisfactory precision with relative standard deviation of

A rapid, accurate and sensitive method, using the stable isotope labeling (SIL), microwave-assisted dispersive liquid-liquid micro extraction (MADLLME) and the ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), was developed and validated for the determination of hydroxyl UV Filters in environmental water samples. A pair of new isotopic tags D0-/D3-1-methylindole-3-acetic acid (D0-/D3-MIAA) is synthesized, with which a simple yet efficient pretreatment MADLLME-SIL is developed. Under the optimized conditions (80℃, 240W, 180s), the sample pretreatment including analyte extraction, pre-concentration and isotope labeling can be finished conveniently in only 9min. D0-/D3-MIAA labeling improves the chromatographic retention by strengthening the hydrophobicity and enhances the MS response for 3-4 orders of magnitude. Excellent linearity is established by the H/D ratios of 1/10-10/1 with the correlation coefficients >0.9990. The quite low detection limits (0.54-1.79ng/L) are achieved, ensuring the trace detection. This method is successfully applied to a series of environmental water samples. The recoveries (93.2%~103.5%) are significantly improved and the analysis time is largely reduced (

The present study reports on a Zr-based metal–organic framework (MOF) with 2-amino-benzenedicarboxylic acid (UiO-66-NH2) ligand as a special and efficient adsorbent for pretreatment of chlorophenoxy acid herbicides (CPAHs) from biosamples. Owing to the ionic bond formation between the amino groups of the MOF and the carboxyl groups of CPAHs, CPAHs could be selectively and easily adsorbed by the MOF material. On the other hand, by regulation of the pH value of the eluting solvent, CPAHs could also be easily eluted from the MOF. In addition, by characterization with the techniques of scanning electron microscopy, powder X-ray diffraction, and Brunner–Emmett–Teller surface area analysis, the as-synthesized material showed good characteristics of morphology, high specific surface area and large pore volume. Its performance was evaluated by the dispersive micro-solid-phase extraction (D-μ-SPE) of CPAHs from vegetable samples, followed by high-performance liquid chromatography (HPLC) analysis. The parameters affecting the extraction efficiency were investigated and properly optimized. By combining the optimized D-μ-SPE conditions with HPLC, a sensitive method for the determination of CPAHs was developed. In the linearity range of 10–1000 pmol mL−1, the correlation coefficients were satisfactory (R2 > 0.9985) for all the analytes; the LODs were 0.16–0.37 ng g−1 based on a signal-to-noise ratio of 3; the intra-day and inter-day precision values (based on the relative standard deviation, n = 3) were under 3.1% and 5.9%, respectively; and satisfactory recoveries for all analytes in all samples were in the range of 82.3–102%. The results demonstrate that the synthesized Zr-MOF has a potential application of adsorbing CPAHs from complex matrix.

A zirconium-based metal–organic frameworks (MOF), with 2-aminoterephthalic acid as linkers, named UiO-66-NH2, has been synthetized and characterized in a dispersive solid-phase extraction (DSPE) procedure in combination with high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for the pre-concentration and detection of sialic acids (SAs) in serum samples. In this study, UiO-66-NH2 was employed for the first time as a novel DSPE sorbent for sample pretreatment. Parameters which influence the extraction efficiency such as the amount of MOF, nature of the desorption solvent and its amount, adsorption time and desorption time were investigated and optimized. Under the optimized conditions, better extraction results were obtained by UiO-66-NH2 based DSPE for the extraction of SAs from serum samples than traditional sample preparation methods. Detection limits of the method as low as 0.16 pmol for N-glycolylneuraminic acid (Neu5Gc) and 0.11 pmol for N-acetylneuraminic acid (Neu5Ac) were obtained, with determination coefficients (R2) higher than 0.9995 for the range 10–1000 pmol L−1, average recoveries of >91.3% at three different spiked levels (1, 5 and 10 ng mL−1), and relative standard deviation (RSD) values below 3.4%. The proposed method was demonstrated to be sensitive enough for determination of SAs from bio-samples.

A simple, low-cost, rapid, sensitive and specific analytical method for ractopamine (RAC) screening in foodstuffs based on fluorescent labeling coupled with ultrasonic-assisted dispersive liquid–liquid microextraction (UA-DLLME) was established by high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). In this study, 2-(11H-benzo[a]carbazol-11-yl)ethyl chloroformate (BCEC-Cl) was first employed as the labeling reagent for RAC, and the labeled sample was directly submitted to UA-DLLME. In order to obtain optimal experimental conditions, several important parameters including the kinds of extraction and dispersive solvent, pH of the solution, salt effect and the volume of sample solution affecting the UA-DLLME were optimized systematically. Moreover, the main parameters including ultrasonic time (T), extraction solvent volume (EV) and disperser solvent volume (DV) were further optimized by response surface methodology (RSM) based on a Box–Behnken design (BBD). Under the optimal conditions, the quantitative linear range of the targeted analyte was 2–100 ng mL−1, and the correlation coefficient was 0.9995. The low limit of detection (LOD) and limit of quantification (LOQ) for RAC were 0.4 ng mL−1 and 1.3 ng mL−1, respectively. The developed method combining the merits of fluorescent labeling and UA-DLLME facilitated high-sensitivity and high-throughput sample screening. The novel method was successfully applied to trace RAC screening in foodstuffs with excellent applicability and good reproducibility. This method was proven to be inexpensive, sensitive, efficient, accurate and reliable for trace RAC screening.

A simple sample pretreatment method of dispersive liquid–liquid microextraction (DLLME) was developed for fast and efficient extraction of 8 chlorophenoxy acid herbicides (CPAHs). The extracted CPAHs were labeled with a sensitive derivatization reagent and measured by high performance liquid chromatography-fluorescence detection (HPLC-FLD). Good linear correlations were obtained for all analytes with R2 > 0.9999. The limits of detection (LODs) were

In this work, a dispersive solid phase extraction (d-SPE) method for sulfonamides (SAs) has been developed using a stable and mesoporous metal organic framework (University in Oslo 67, UiO-67) as adsorbent, which was synthesized by coordination of Zr4+ ions with 4, 4-biphenyl-dicarboxylicacid (H2BPDC) through a facile one-pot method. Owing to the synergistic effects of π-π interaction, hydrogen bonding, hydrophobic interaction and size match between SAs and the adsorbent, the extraction performance of UiO-67 for SAs was obviously improved. The adsorption behavior, evaluated by the kinetic models, showed that the intraparticle diffusion was involved during the adsorption process. The proper match between the pore size of UiO-67 (3.49 nm) and the molecular sizes of SAs (1.1 nm × 0.65 nm) not only allowed SAs to diffuse intraparticle but also permitted them to adjust their configurations to form hydrogen bonding with the UiO-67. By combination with HPLC analysis, a simple, sensitive, accurate and precise method for detection of SAs has been established. The method proposed in this work showed good performances, including wide linearity (14.6–250 ng/g) with high correlation coefficients (R ≥ 0.9991), low limits of detection (LODs, 0.7–6.5 ng/g for all SAs), satisfactory precision (Intra-day RSDs ≤ 3.4%, inter-day RSDs ≤ 4.7%), and high accuracy (recovery: 83.4–103.8%). Furthermore, benefiting from the mesoporous structure and the Zr cluster center as well as the stability, UiO-67 shows great potential to be an excellent adsorbent of SPE for extraction of SAs from other complex matrices.

A sensitive and inexpensive method involving ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and pre-column derivatization followed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) was developed for the analysis of glycyrrhetinic acid. In this work, glycyrrhetinic acid could be obtained by hydrolyzing glycyrrhizic acid to remove glucuronic acid and subsequently extracted by UA-DLLME using chloroform and acetone as the extraction and disperser solvents, respectively. The sample extraction was firstly concentrated to dry under nitrogen and then rapidly derivatized with 2-(12-oxobenzo[b]acridin-5(12H)-yl)-ethyl-4-toluenesulfonate (BAETS) after the UA-DLLME. The prime parameters influencing the UA-DLLME and derivatization procedure were optimized using response surface methodology. Under the optimum conditions, the proposed method has a better linearity in a wider range of 6–300 ng mL−1 and a high square of correlation coefficient (R 2) at 0.9994. Limit of detection and limit of quantification were found to be 1.7 ng mL−1 and 5.8 ng mL−1, respectively. The proposed method was applied to the analysis of glycyrrhetinic acid in liquorice, liquorice apricot and sugar plum samples. For the analysis of the spiked samples, the spiked recoveries were in the range of 90.4–103.0 % with RSD less than 5.18 %. All results demonstrated that the UA-DLLME-HPLC-FLD (ultrasound-assisted dispersive liquid–liquid microextraction-high-performance liquid chromatography with fluorescence detection) was a sensitive, accurate, efficient analytical method for the determination of glycyrrhetinic acid.

Determination of plant growth regulators (PGRs) in a signal transduction system (STS) is significant for transgenic food safety, but may be challenged by poor accuracy and analyte instability. In this work, a microwave-assisted extraction-derivatization (MAED) method is developed for six acidic PGRs in oil samples, allowing an efficient (

Free fatty acids (FFAs) in edible oils are one of the most frequently determined quality indices during production storage and marketing In this study a simple stable and sensitive method for the simultaneous determination of saturated and unsaturated FFAs from edible oils using 2-(11H benzo[a]carbazol-11-yl)-ethyl-4-methylbenzenesulphonate (BCETS) as labelling reagent with fluorescence detection has been established FFAs are derivatized by BCETS and separated on a reversed-phase Eclipse XDB-C(8) column with a gradient elution The results indicated that all FFAs were found to be given an excellent linear response with correlation coefficients of >0 9994 The detection limits at a signal-to noise ratio of 3 were in the range of 0 22-1 06 ng/mL. When applied to Lycium barbarum seed oils the developed method showed good reproducibility The effect of extraction methods including supercritical CO(2) and organic solvent extraction on the FFAs composition has also been investigated Meanwhile this method exhibits powerful potential for the trace analysis of short- and long chain free fatty acids from edible oils food-stuff and other complex samples (C) 2010 Elsevier Ltd All rights reserved

Oleanolic acid (OA) and ursolic acid (UA) are the ubiquitous triterpenic acids in plant kingdom and have multiple biological effects. In the present study, a highly sensitive and selective method using a dual-sensitive probe 2-(5-benzoacridine)ethyl-p-toluenesulfonate (BAETS) as pre-column labeling reagent has been developed for rapid determination of the triterpenes OA and UA by HPLC with fluorescence detection (FLD) and online mass spectrometry identification. Response surface methodology as an efficient tool was employed to optimize the ultrasonic-assisted extraction of triterpenic acids from Swertia plants and the pre-column derivatization reaction, respectively, which ensured the highest triterpenic acids recoveries within the shortest extraction time and the sufficient labeling of the analyzed components. Fast separation of the isomers OA and UA could be achieved on a Hypersil BDS C8 column within 7 min. Both of OA and UA gave the good correlation coefficients of 0.9999. This developed method offered the satisfactory detection limits of 1.10 and 1.30 ng mL(-1) for UA and OA, respectively. When applied to Swertia species, it showed good reproducibility. (C) 2011 Elsevier B.V. All rights reserved.

P>Oil extractions from red pepper seed were performed by supercritical CO(2). Three-level Box-Behnken factorial design (BBD) from response surface methodology (RSM) was applied to optimise the main extraction conditions including pressure, temperature and concentration of modifier (ethanol). The optimum conditions were as follows: extraction pressure, 27.17 MPa; extraction temperature, 47.67 degrees C; and the added concentration of modifier, 8.11 vol.%. Under the optimum conditions, the oil yield of 18.4% was obtained, which was well matched with the predicted yield. A simple, stable and sensitive method for the simultaneous determination of saturated and unsaturated free fatty acids in extracted oils using 2-(11H-benzo[a]carbazol-11-yl)-ethyl-4-methylbenzenesulfonate (BCETS) as labelling reagent with fluorescence detection has been developed. All of free fatty acids (FFA) were found to give a linear response with correlation coefficients of > 0.9991. The detection limits at a signal-to-noise ratio (S/N) of three are in the range of 19.06-41.19 fmol. This method should have powerful potential for the trace analysis of short- and long-chain FFA from edible oils, foodstuff and other complex samples.

Supercritical CO2 fluid extraction (SFE-CO2) of Zanthoxylum bungeanum (Z. bungeanum) seed oil was investigated. To optimize the SFE process, three-level Box-Behnken factorial design and response surface meth- odology (RSM) were applied to optimize the extraction conditions, including pressure, temperature and amount of modifier. The optimum conditions were as follows: extraction pressure, 29.28 MPa; extraction temperature, 41.19 C; and the added amount of modifier, 10.94%. The experimental results showed that the maximum extraction yield was 21.85 ± 0.23% (n = 3) under the proposed conditions. The compositional analysis of Z. bungeanum seed oil was performed by HPLC-FLD-MS using a new labeling reagent of 2-(11H-benzo(a)carbazol-11-yl)-ethyl- 4-methyl benzenesulfonate (BCETS). The results indicated that the Z. bungeanum seed oil contained mainly unsatu- rated fatty acids, including C18:3, C22:6, C20:4, C18:2, C18:1 and C20:1, which accounted for 84.0% (mass per- centage) of the total amount. The antioxidant activity of seed oil obtained by Box-Behnken design concerning the DPPH radical was investigated, and this indicated that the pressure and the amount of added modifier had positive effects on the antioxidant activity, but the effect of the temperature elevation is complicated, depending on the nature of the extracted contents.

BACKGROUND: Supercritical CO(2) was utilised to extract Chinese star anise seed oil (CSASO), and a three-level Box - Behnken factorial design from response surface methodology was applied to optimise the extraction conditions, including pressure, temperature and amount of modifier (ethanol). The compositional analysis of fatty acids in CSASO was performed by HPLC with fluorescence detection using 2-(11H-benzo[a]carbazol-11-yl)-ethyl-4-methylbenzenesulfonate (BCETS) as labelling reagent. Identification was carried out by online atmospheric chemical ionisation-mass spectrometry. RESULTS: The optimum extraction conditions were as follows: extraction pressure, 27.72 MPa, extraction temperature, 46.22 degrees C, and amount of modifier, 8.58 vol.%. The experimental result showed that the maximum extraction yield was 25.31 +/- 0.22% (w/w) under the conditions proposed. The compositional analysis indicated that CSASO mainly contained C18: 2, C18 : 1, C18 : 3, C20 :4, C16, C18 and C20 fatty acids. CONCLUSION: In this study, a fast, simple and high-efficiency supercritical technique for extracting oil from Chinese star anise seed was developed. Simultaneous determination of fatty acids in CSASO using BCETS as the labelling reagent with HPLC fluorescence detection and online mass spectroscopy identification has been successfully achieved. (C) 2010 Society of Chemical Industry