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Chinese Journal of Chromatography
2015, Vol. 33, No. 6
Online: 08 June 2015

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Progress in quantitative methods based on liquid chromatography-mass spectrometry for drug metabolizing enzymes in human liver microsomes WANG Huanhuan, LÜ Yayao, PENG Bo, QIAN Xiaohong, ZHANG Yangjun 2015, 33 (6):  553-557.  DOI: 10.3724/SP.J.1123.2015.03023 Abstract ( 739 )   [Full Text(HTML)] () PDF (780KB) ( 298 )   Cytochrome P450 (CYP) enzymes and uridine 5-diphospho-glucuronosyltransferase (UGT) enzymes are critical enzymes for drug metabolism. Both chemical drugs and traditional Chinese medicines are converted to more readily excreted compounds by drug metabolizing enzymes in human livers. Because of the disparate expression of CYP and UGT enzymes among different individuals, accurate quantification of these enzymes is essential for drug pharmacology, drug-drug interactions and drug clinical applications. The research progress in quantitative methods based on liquid chromatography-mass spectrometry for drug metabolizing enzymes in human liver microsomes in the recent decade is reviewed.

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Influence of the distortion of gradient profile on peak width in gradient liquid chromatography WU Shun, HAO Weiqiang, YUE Bangyi, ZHANG Peipei, DI Bin, CHEN Qiang 2015, 33 (6):  558-562.  DOI: 10.3724/SP.J.1123.2015.01013 Abstract ( 651 )   [Full Text(HTML)] () PDF (808KB) ( 243 )   In gradient liquid chromatography, the gradient profile may be distorted because of the effects of solvent mixing and axial dispersion. Such effects will be significant especially when stepwise gradient and linear gradient with high slope are applied. In this work, we discussed the influence of the distortion of gradient profile on the peak width. Firstly, the chromatographic peaks were measured under linear and stepwise gradient conditions where a C18 column was used as the stationary phase, a mixture of methanol and water as the mobile phase, and biphenyl and acetophenone as the samples. Then, the response of methanol under corresponding conditions was recorded by disconnecting the column and the detection wavelength was set at 205 nm. The gradient profile at the column inlet was calculated from the methanol response profile. The theoretical values of the peak width were calculated from the set gradient profile and the gradient profile obtained at the column inlet respectively. The theoretical values were compared with the experimental ones. It is shown that the distortion of gradient profile does affect the peak width. When such influence is taken into account, the theoretical and experimental values of the peak width are well consistent.

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A simple preparation method of an electric heating apparatus for heating capillary chromatographic columns and its application in liquid chromatography-mass spectrometry system JIN Zuyao, LÜ Yayao, ZHOU Shanshan, HAO Feiran, FU Bin, YING Wantao, QIAN Xiaohong, ZHANG Yangjun 2015, 33 (6):  563-570.  DOI: 10.3724/SP.J.1123.2015.01036 Abstract ( 513 )   [Full Text(HTML)] () PDF (1308KB) ( 122 )   For deep coverage of proteome, especially in performing qualitative identification and quantitative analysis of low-abundance proteins, the most commonly used method is the application of a longer capillary chromatographic column or a capillary column packed with smaller particle sizes. However, this causes another problem, the very high back pressure which results in liquid leaks in some connection parts in a liquid chromatograph. To solve this problem, an electric heating apparatus was developed to raise the temperature of a capillary column for reducing its back pressure, which was further applied in a capillary high performance liquid chromatography-tandem mass spectrometry system (cHPLC-MS/MS), and evaluated in the terms of chromatographic column back pressure and chromatographic column efficiency using bovine serum albumin (BSA) tryptic digests and yeast tryptic digests, separately. The results showed that at the optimum current, our electric heating apparatus could reduce the column pressure of a capillary column packed with 3 μm packing materials by at least 50% during the separation of BSA tryptic digestion and yeast tryptic digestion, compared with that without electric heating. The column efficiency was also increased slightly. This suggested that the electric heating apparatus can significantly reduce the column pressure, which provides an efficient way to use capillary chromatographic columns packed with smaller sizes of particles at a lower pressure.

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Simultaneous determination of ten benzotriazole ultraviolet stabilizers in food contact plastic materials by solid phase extraction and ultra performance liquid chromatography with tandem mass spectrometry GOU Xinlei, ZHAO Xinying, CHI Haitao, GAO Xia, ZHOU Mingqiang, LIU Weili 2015, 33 (6):  571-576.  DOI: 10.3724/SP.J.1123.2015.03019 Abstract ( 696 )   [Full Text(HTML)] () PDF (976KB) ( 228 )   A sensitive method was developed for the simultaneous determination of ten benzotriazole ultraviolet stabilizers in food contact plastic materials by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample was extracted by methanol-dichloromethane, and purified by a C18 solid-phase extraction (SPE) column. The separation was performed by using water containing 0.1% (v/v) formic acid and methanol as the mobile phases with gradient elution at a flow rate of 0.3 mL/min. The electrospray ionization (ESI) source in positive ion mode was used for the analysis of the ten benzotriazole ultraviolet stabilizers in multiple reaction monitoring (MRM) mode. The results showed that the standard curves were obtained with good correlation coefficients (r2>0.996) in their linear concentration ranges. The limits of detection (LODs, S/N=3) for the ten benzotriazole ultraviolet stabilizers were in the range of 0.6-1.6 μg/kg. The mean recoveries for the ten benzotriazole ultraviolet stabilizers at three spiked levels (low, medium and high) were 75.2%-85.3% with relative standard deviations of 1.0%-5.7%. Ten kinds of food contact plastic materials were tested, and 2,2'-methylenebis(6-(benzotriazol-2-yl)-4-tert-octylphenol) (UV-360) was found in a sample of polyethylene (PE) material. The method is accurate, simple, rapid and feasible for the simultaneous determination of benzotriazole ultraviolet stabilizers in food plastic materials.

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Determination of anthocyanins in the peel of sweet cherry by ultra performance liquid chromatography-tandem mass spectrometry WEI Hairong, YI Xibin, TAN Yue, ZONG Xiaojuan, WANG Jiawei, XU Li, LIU Qingzhong 2015, 33 (6):  577-582.  DOI: 10.3724/SP.J.1123.2015.01020 Abstract ( 655 )   [Full Text(HTML)] () PDF (1422KB) ( 227 )   A method for the determination of seven anthocyanins in the peel of sweet cherry was developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample was extracted by methanol containing 0.1%(v/v) hydrochloric acid, and then purified by AB-8 macroporous resins. The separation was carried out on a Phenomenex Kinetex column (100 mm×4.6 mm, 2.6 μm) with mobile phase of 0.1%(v/v) formic acid aqueous solution containing 5 mmol/L ammonium formate and methanol. The sample solution was detected by UPLC-MS/MS with ESI under positive ion and multi reaction monitoring (MRM) modes. The results showed that the limits of quantification (LOQs) for the seven target compounds were 0.26-1.42 μg/kg. The seven anthocyanin standards showed a good linearity in the range of 0-100 μg/L with the correlation coefficients (r2) of 0.9964-0.9993. The average recoveries of the seven anthocyanins were 97.2%-105.4%, and the relative standard deviations (RSDs) were 1.9%-5.8%. The mature fruit samples of sweet cherry red variety "Tieton" and the yellow variety "13-33" were analyzed by this method. The results showed that the anthocyanin composition and contents were significantly different between the two varieties. This method can be used for rapid identification and the determination of anthocyanin components in sweet cherry fruits due to its simple operation, high sensitivity, good reproducibility and covering a wide range of anthocyanins.

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Direct analysis of 38 polyphenols in wine by ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry ZHANG Xieguang, ZHENG Yanjie, ZENG Yongting, LIU Wenli 2015, 33 (6):  583-589.  DOI: 10.3724/SP.J.1123.2015.01040 Abstract ( 537 )   [Full Text(HTML)] () PDF (837KB) ( 163 )   Wine has been described previously as a rich source of polyphenols. However, an accurate screening of its complete phenolic profile is still lacking. In the present work, the analysis of 38 polyphenols in wine using ultra high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UPLC-LTQ/Orbitrap MS) was explored. Wines were directly detected. The sample was loaded onto a Thermo Hypersil Gold C18 column (100 mm×2.1 mm, 1.9 μm) using a gradient elution of acetonitrile/water containing 0.1% (v/v) formic acid for the separation. UPLC-LTQ/Orbitrap mass spectrometer acquired full scan MS date for quantification, and data dependent MS2 product ion spectra for identification and/or confirmation. The regression coefficients (R2) for the calibration curves (two orders of magnitude up to the lowest calibration level) in the study were ≥0.99. The limits of detection for the 38 compounds were 0.002-0.50 mg/kg. The average recoveries at three spiked levels were in the range of 90%-102% with the relative standard deviations (RSDs) of 0.51%-2.56%. Mass errors were always ≤ 5 ppm. This procedure was then successfully applied to the analysis of the polyphenols in wines.

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Determination of five avermectins in bovine liver by on-line solid-phase extraction with hydrophobic monolithic column coupled with high performance liquid chromatography-tandem mass spectrometry LI Xin, ZHANG Yaoqin, AI Lianfeng, WANG Xuesheng, WANG Manman, XU Houjun, HAO Yulan 2015, 33 (6):  590-596.  DOI: 10.3724/SP.J.1123.2015.02062 Abstract ( 583 )   [Full Text(HTML)] () PDF (992KB) ( 183 )   A method based on on-line solid-phase extraction (SPE) with hydrophobic monolithic column coupled with high performance liquid chromatography-tandem mass spectrometry was developed for the simultaneous determination of five avermectins in bovine liver. A poly(butyl methacrylate-co-ethylene dimethacrylate) monolithic column was used as the sorbent. The parameters influenced on on-line SPE and separation process such as the loading mobile phase, the eluting flow rate and the solvent for the separation were investigated in detail. Blank samples, spiked samples, matrix effect and recovery experiments were investigated to evaluate the extraction efficiency and potential interfering compounds originating from the matrix. Under the optimized conditions, the method showed a linear range of 1-100 μg/L and the quantification limit of 5 μg/kg for each analyte. The presented method gave recoveries of 77.4%-98.4%. The relative standard deviations of intra-day and inter-day were 4.46%-8.03% and 4.79%-8.68%, respectively. Moreover, no significant changes were found in the extraction performance after more than 400 usages on one monolithic column, and even on the monoliths with various batches. The feasibility of the developed poly(butyl methacrylate-co-ethylene dimethacrylate) monolithic column based on the on-line SPE method for the determination of avermectins was further demonstrated by the analysis of real samples.

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Rapid determination of 204 pesticide residues in tea by ultra performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry YU Lu, SONG Wei, LÜ Yaning, ZHAO Muyu, ZHOU Fangfang, HU Yanyun, ZHENG Ping 2015, 33 (6):  597-612.  DOI: 10.3724/SP.J.1123.2015.02056 Abstract ( 633 )   [Full Text(HTML)] () PDF (1689KB) ( 292 )   An analytical method was established for the simultaneous determination of 204 pesticide residues in tea by ultra performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS). The samples were extracted with acetonitrile, and cleaned-up by solid phase extraction (SPE) with a Carb-PSA cartridge, eluted with acetonitrile-toluene (3:1, v/v), determined by UPLC-Q-TOF/MS and quantified by external standard method. A data base of the accurate mass numbers and a library which contains the 204 pesticides were established. The automatic retrieval of detection results was carried on according to the characteristics of the compound, such as accurate mass, retention time, isotopic ratio, and so on. Based on the above results, the qualitative identifications of the 204 pesticides were accomplished without the contrast of standard substances. The results indicated that this method can be used to determine the 204 pesticides in tea. At the three spiked levels of 10, 20, 50 μg/kg, mean recoveries for the 204 pesticides in tea were between 68.1% and 117.2%, with the relative standard deviations (RSDs) ranging from 3.1% to 18.9%. The limits of quantification for the 204 pesticides were lower than 10 μg/kg. The method has been applied to four positive samples, and the results generally accord with the detection results by the method of GB/T 23205-2008. This method has the characteristics of high efficiency, as well as high sensitivity and accuracy, which can meet the requirement of the determination of the 204 pesticides in tea.

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Metabolic profiling analysis of amino metabolites in plant extract based on pre-column derivatization-ultra high performance liquid chromatography-mass spectrometry ZHANG Junjie, ZHAO Chunxia, ZHAO Yanni, ZHAO Jieyu, LI Lili, LU Xin, XU Guowang 2015, 33 (6):  613-621.  DOI: 10.3724/SP.J.1123.2015.01028 Abstract ( 590 )   [Full Text(HTML)] () PDF (2497KB) ( 152 )   Amino metabolites are important compounds that play a key role in plant growth and development. A metabolic profiling analysis method of amino metabolites in plant extract was developed based on pre-column derivatization-ultra high performance liquid chromatography-mass spectrometry. Using the tobacco leaf as an example, a total of 87 amino metabolites, including amino acids, amines, peptides, alkaloids etc. were detected. The repeatability of the method was good with RSDs of 85 amino metabolites between 1.5% and 18.8%. Forty-three amino metabolites validated by standard samples showed good linearity with the correlation coefficients of 0.993-0.999, covered linear range of four orders of magnitude. The limits of detection were 0.03-6.58 ng/mL. The intra-day and inter-day precisions were 0.7%-15.6% and 0.8%-22.9%, respectively. The recoveries were 74.4%-122.7%. The influence of topping on metabolic profiling of amino metabolites in fresh tobacco was investigated using the developed method. The results showed that the amino metabolites in the upper tobacco leaves were most affected than those in the middle and lower leaves. Metabolism of amino metabolites in the upper leaves after topping was mainly towards the alkaloid synthesis. The method integrated the advantages of triple quadrupole mass spectrometry and high resolution quadrupole-time of flight mass spectrometry. It can be used for metabolic profiling analysis of amino metabolites in plant extract with high sensitivity and selectivity.

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Determination of seven phthalate metabolites in human urine by high performance liquid chromatography-tandem mass spectrometry GAO Hui, XU Yuanyuan, SUN Li, JIN Zhongxiu, HU Haiting, SHENG Jie, REN Lingling, TAO Fangbiao 2015, 33 (6):  622-627.  DOI: 10.3724/SP.J.1123.2015.01037 Abstract ( 917 )   [Full Text(HTML)] () PDF (1465KB) ( 292 )   A method has been developed for the analysis of seven metabolites of phthalates in human urine by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The urine samples were hydrolyzed with glucuronidase followed by purification with solid-phase extraction (SPE) cartridges. Both 0.1% formic acid in water (v/v) and 0.1% formic acid in acetonitrile were used as the mobile phases in a gradient mode. The chromatographic separation was achieved on a phenyl column. Mass detection was then conducted by electrospray ionization in negative ion mode and multiple reaction monitoring mode. The components were quantified by stable isotope-labelled (13C-) phthalate monoester internal standards. The calibration curves of the seven phthalates metabolites showed good linear relationships in the range of 0.2-200.0 μg/L (r>0.99976). The recoveries at three levels were from 88.8% to 108.9% with relative standard deviations no more than 17.05%. The limits of detection of the method were 13.43-80.2 ng/L. The limits of quantification were 44.77-267.37 ng/L. This method was successfully applied to the determination of metabolism of phthalates in human urine with efficiency, increased accuracy and high sensitivity.

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Determination of peptide and protein diversity in venom of the spider Selenocosmia jiafu by high performance liquid chromatography and mass spectrometry HU Zhaotun, XIAO Zhen, ZHOU Xi, CHEN Jia, CHEN Bo, LIU Zhonghua 2015, 33 (6):  628-633.  DOI: 10.3724/SP.J.1123.2015.01050 Abstract ( 668 )   [Full Text(HTML)] () PDF (1645KB) ( 319 )   Selenocosmia jiafu (S. jiafu) is recently identified as a new species of spider in P. R. China. These medium bodied venomous spiders are distributed mainly in the hilly areas of southwest of China, mostly at Yunnan and Guangxi Provinces. In order to understand the composition of the S. jiafu venom, we performed a preliminary analysis of this venom using reversed-phase high performance liquid chromatography (RP-HPLC), matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The S. jiafu venom was separated by RP-HPLC in an analytical C18 column (phenomenex 100 Å, 250 mm×4.6 mm, 5 μm) equilibrated with solution A (distilled water with 0.1% trifluoroacetic acid), using a gradient from 0% to 50% of solution B (acetonitrile with 0.1% trifluoroacetic acid) over 50 min with a flow rate of 1 mL/min. The isolated venom proteins were treated with in-gel digestion separated by SDS-PAGE and then identified by liquid chromatography-electrospray ionization quadrupole-time of flight mass spectrometry (LC-ESI-QTOF-MS) techniques. The results show that more than 40 fractions eluted were monitored at 215 nm in the RP-HPLC chromatogram of the venom of the spider S. jiafu. Most of the fractions were eluted with retention times of 5-15 min and 25-40 min, corresponding to 5%-15% and 25%-40% acetonitrile, respectively. The venom contains 238 peptides that follow a bimodal distribution, with about 62.5% of the peptides having a relative molecular mass of 3000-4500 and about 33.2% of the peptides having a relative molecular mass of 1000-3000. This distribution model is rather different from those of peptides from other tarantula spider venoms analyzed. To explore the relative molecular mass distribution of the venom proteins, the venom was analyzed by SDS-PAGE using standard protocols. Except for peptides with relative molecular mass lower than 10000, the SDS-PAGE electrophoresis revealed three more obvious bands around 50, 72 and 90 kD respectively. Further MS analysis indicated that there are mainly hemocyanin, potassium ion channel protein, calcium protease and so on. Altogether, this study not only indicated there are many peptides and proteins in the S. jiafu venom, but also provided a basis for further case-by-case investigation of peptide toxins from this venom.

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Solidified floating organic drop microextraction combined with high performance liquid chromatography for the determination of carbamazepine in human plasma and urine samples Mohammad ASADI, Ali Mohammad HAJI SHABANI, Shayessteh DADFARNIA, Bijan ABBASI 2015, 33 (6):  634-641.  DOI: 10.3724/SP.J.1123.2015.02072 Abstract ( 410 )   [Full Text(HTML)] () PDF (674KB) ( 117 )   Solidified floating organic drop microextraction (SFODME) in combination with high performance liquid chromatography was used for separation/preconcentration and determination of carbamazepine (CBZ) in human plasma and urine samples. Parameters that affect the extraction efficiency such as the type and volume of extraction solvent, ionic strength, sodium hydroxide concentration, stirring rate, sample volume and extraction time, were investigated and optimized. Under the optimum conditions (extraction solvent, 40 μL of 1-undecanol; sodium hydroxide concentration, 1 mol/L; temperature, 50 ℃; stirring speed, 400 r/min; sample volume, 8 mL; sodium chloride concentration, 3% (w/v) and extraction time, 60 min) the calibration curve was found to be linear in the mass concentration range of 0.4-700.0 μg/L. The limit of detection (LOD) was 0.1 μg/L and the relative standard deviation (RSD) for six replicate extraction and determination of carbamazepine at 100 μg/L level was found to be 4.1%. The method was successfully applied to the determination of CBZ in human plasma and urine samples.

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Comparison among three anion exchange chromatographic supports to capture erythropoietin from cell culture supernatant Lourdes Lourdes HERNÁNDEZ, Diobel STEWART, Lourdes ZUMALACÁRREGUI, Daniel AMARO 2015, 33 (6):  642-646.  DOI: 10.3724/SP.J.1123.2015.01026 Abstract ( 632 )   [Full Text(HTML)] () PDF (605KB) ( 150 )   Affinity and ion exchange conventional chromatography have been used to capture erythropoietin (EPO) from mammalian cell culture supernatant. Currently, chromatographic adsorbent perfusion is available, however a limited number of applications have been found in the literature. In this work, three anion exchange chromatographic supports (gel, membrane and monolithic) were evaluated in the capture step of the recombinant erythropoietin purification process. The influences of load and flow rate on each support performance were analyzed. Also the purity of the EPO molecules was determined. A productivity analysis, as a decision tool for larger scale implementation, was done. As a conclusion, the evaluated supports are technically suitable to capture EPO with adequate recovery and good purity. However, the monolithic column admits high operating velocity, showing the highest adsorption capacity and productivity.

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Enantioseparation of 3α-acyloxy-6β-acetoxyltropane compounds with Chiralpak AD and Chiralcel OD-H chiral stationary phases CHENG Bin, XIE Yifan, HU Youmin, LIU Huizhong, NIU Yinyao, LU Yang 2015, 33 (6):  647-651.  DOI: 10.3724/SP.J.1123.2015.01038 Abstract ( 544 )   [Full Text(HTML)] () PDF (881KB) ( 128 )   Six 3α-acyloxy-6β-acetoxyltropane compounds were enantioseparated by high performance liquid chromatography with amylose-based chiral stationary phase Chiralpak AD and cellulose-based chiral stationary phase Chiralcel OD-H in the normal phase mode, using various mixtures of n-hexane-isopropanol as mobile phases. The enantiomers 6 were completely separated on a Chiralpak AD column. While the enantiomers 1, 4 and 3 got complete, baseline and basic separation respectively on a Chiralcel OD-H column. However, the enantiomers 6 were partially separated on the Chiralcel OD-H column and enantiomers 1 could not be separated on the Chiralpak AD column. This indicated that the cave structure of chiral stationary phase exerted great effect on the resolutions. The enantiomers 5 could not be separated on both of the chiral stationary phases. The main possible mechanism of chiral resolution involves in spatial adaptability and molecular interactions between chiral stationary phases and compounds. The substituents in C-3α position of 3α-acyloxy-6β-acetoxyltropane compounds play an important role in spatial adaptability. And it was suggested that the steric hindrance effect of the substituent in C-3α position was the key factor of determining the selective recognition of chiral stationary phase to the enantiomers of 3α-acyloxy-6β-acetoxyltropane compounds. Besides, the molecular interaction, such as π-π interaction, also exerts great influence to the chiral resolution. This study provides a reference for the enantioseparation of many other tropane derivatives.

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Rapid determination of thiabendazole and carbendazim in concentrated fruit juices by ultra-high performance liquid chromatography-tandem mass spectrometry ZHENG Xiangping, DING Liping, CHEN Zhitao, GUO Jing, ZHANG Rui, WU Wenfan 2015, 33 (6):  652-656.  DOI: 10.3724/SP.J.1123.2015.01034 Abstract ( 575 )   [Full Text(HTML)] () PDF (802KB) ( 152 )   A method was developed for the rapid determination of thiabendazole and carbendazim residues in concentrated fruit juices by using ultra-high performance liquid chromatography (UHPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS), and quantified by matrix-matched standard solution in external standard method. The residues in the samples were extracted by ethyl acetate, and then analyzed by using UHPLC-MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization with an Waters ACQUITY UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) as the analytical column. Good linearities were obtained in the range of 0.5-10 μg/kg for both pesticides with correlation coefficients greater than 0.99. The recovery experiments were carried out by spiking standards into blank samples of apple, peach, orange, pear, grape juices at three levels of 0.5, 1.0 and 5.0 μg/kg. The recoveries of thiabendazole and carbendazim were from 76.98% to 108.7% with the relative standard deviations (RSD) of 2.95%-9.99%. For both pesticides in different matrices, the limits of detection (S/N=3) were in the range of 0.12-0.23 μg/kg. Meanwhile, the pyrolysis mechanism and matrix effects for the determination of thiabendazole and carbendazim in concentrated fruit juices were investigated in this study. The method is simple, rapid and accurate, and can be used for the routine analysis of thiabendazole and carbendazim in concentrated fruit juices.

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Determination of dimethyl yellow and diethyl yellow in yuba and dried beancurd by modified QuEChERS method and liquid chromatography-tandem mass spectrometry FAN Sufang, LI Qiang, MA Junmei, LI Hui, ZHANG Yan 2015, 33 (6):  657-661.  DOI: 10.3724/SP.J.1123.2015.01046 Abstract ( 655 )   [Full Text(HTML)] () PDF (804KB) ( 183 )   A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method followed by liquid chromatography-tandem mass spectrometric analysis was developed for the determination of dimethyl yellow and diethyl yellow in yuba and dried beancurd. Yuba and dried beancurd samples were soaked by deionized water, then acetonitrile was added to extract the analytes. Sodium chloride and anhydrous magnesium sulfate were added for liquid-liquid separation. The extracts were cleaned-up by dispersive solid-phase using N-propyl diethylamine. The analytes were separated by liquid chromatography and determined by mass spectrometry. External standard method was used for quantification. The recoveries of dimethyl yellow were in the range of 73.5%-84.5% at spiked levels of 0.3, 1 and 10 μg/kg and the recoveries of diethyl yellow were in range of 70.5%-81.2% at spiked levels of 0.1, 1 and 10 μg/kg; relative standard deviations of the method were lower than 11%. The limit of detection and the limit of quantification of dimethyl yellow were 0.1 μg/kg and 0.3 μg/kg, respectively; the limit of detection and the limit of quantification of diethyl yellow were 0.05 μg/kg and 0.1 μg/kg, respectively. This method can be used in rapid screening and quantitative analysis of dimethyl yellow and diethyl yellow in yuba and dried beancurd.

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Simultaneous determination of monosaccharide and oligosaccharide in rice wine by high performance anion exchange chromatography with integrated pulsed amperometric detection and the establishment of their fingerprints HU Beizhen, DONG Wenhong, XIA Biqi, SONG Weihua, HAN Chao 2015, 33 (6):  662-666.  DOI: 10.3724/SP.J.1123.2015.02053 Abstract ( 698 )   [Full Text(HTML)] () PDF (796KB) ( 143 )   An analytical method for the determination of glucose, fructose, isomaltose, isomaltotriose, maltose, panose and maltotriose was developed by high performance anion exchange chromatography coupled with integrated pulsed amperometric detection. The analysis was performed on a CarboPacTM10 column with gradient elution of NaOH-NaOAc as mobile phases. The seven sugars were well separated in less than 26 min and showed good linear correlation coefficients between 0.5 and 50 mg/L. The detection limits (LODs) were 0.1 g/L. The recoveries ranged from 76.5% to 108.4% at different spiked levels. The relative standard deviations were between 3.02% and 8.23%. The established method was applied in determining the seven sugars in different batches of Shaoxing Jiafan rice wines from different manufacturers. The standard fingerprints were established by median values using the obtained results. Similarities of the fingerprints of the samples to the standard were calculated by using angle cosine. The results showed that the similarities of wines from different manufacturers were significantly different, so the method could be used for the identification of rice wines from different manufacturers.

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Selective separation and determination of isoproterenol on thin layers of bismuth silicate ion-exchanger Vanik GHOULIPOUR, Zahra HASSANKHANI-MAJD 2015, 33 (6):  667-671.  DOI: 10.3724/SP.J.1123.2015.01014 Abstract ( 457 )   [Full Text(HTML)] () PDF (607KB) ( 168 )   A simple and sensitive method for the separation and determination of isoproterenol from other doping drugs has been developed on thin layers of bismuth silicate, a synthetic inorganic ion exchanger as adsorbent in thin layer chromatography (TLC). A mixture of methanol and 0.1 mol/L formic acid (3:7, v/v) was employed as the mobile phase. The development time was 32 min. The quantitative measurement were performed with a Camag TLC Scanner-3 at wavelength (λ) of 410 nm. The isoproterenol recovery in this procedure was 98.9%. The linear correlation coefficient was greater than 0.9871 and the relative standard deviation (RSD) was less than 0.94. The limit of detection (LOD) and limit of quantification (LOQ) were 7.7×10-7mol/L and 3.85 ×10-6mol/L, respectively. This method has been applied in the determination of isoproterenol in dosage forms and in biological fluids.