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Chinese Journal of Chromatography
2015, Vol. 33, No. 7
Online: 08 July 2015

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Affinity capillary electrophoresis for screening proteins interacting with domoic acid WANG Xiaoqian, GAO Tie, HONG Zhuan, QU Feng 2015, 33 (7):  673-677.  DOI: 10.3724/SP.J.1123.2015.03026 Abstract ( 635 )   [Full Text(HTML)] () PDF (812KB) ( 113 )   Domoic acid (DA) is a biological neurotoxin that causes amnesic shellfish poisoning. Study of the interactions between DA and important functional proteins contributes to understand the toxicity mechanism of DA to biological macromolecules. In this paper, the interactions between DA and nine important proteins in plasma, intestine and mitochondria were qualitatively compared by affinity capillary electrophoresis. Proteins were used as affinity ligands while DA as the affinity receptor. Proteins with the concentrations of 0, 0.2, 0.4, 0.6, 0.8 μmol/L were added in the electrophoresis buffer and the migration times of 0.2 mg/mL DA were detected. Then the linear graphs of the variation of DA mobility ratio (ΔM) with the protein mass concentration (L) were drawn. According to the slope value, the relative strength of the interactions between DA and proteins was compared. The results showed that six proteins can interact with DA and the relative strength order was human thrombin > cytochrome C≈trypsin≈immunoglobulin E (Ig E)≈ribonuclease A > λ exonuclease, while ferritin, transferrin and lectin had no affinity with DA. With the advantages of high efficiency, fast analysis and less sample consumption, affinity capillary electrophoresis is a convenient method for screening DA target proteins, which will provide basic information for the toxic mechanism and defence of DA.

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Preparation of an agglomerated ion chromatographic stationary phase with 2,3-ionene and its application in SO42- analysis WANG Muhua, LIU Junwei, HUANG Zhongping, ZHANG Jiajie, ZHU Yan 2015, 33 (7):  678-682.  DOI: 10.3724/SP.J.1123.2015.02052 Abstract ( 460 )   [Full Text(HTML)] () PDF (1718KB) ( 165 )   The poly-electrolyte cation functional group of 2,3-ionene was synthesized with tetramethyl ethylenediamine and 1,3-dibromopropane as the raw materials. Multiporous polystyrene-divinylbenzene microsphere particles (PS-DVB) were produced by swelling method with polystyrene as seeds and sulfonated. Then the 2,3-ionene was bonded on the sulfonated multiporous polystyrene-divinylbenzene microsphere particles by agglomeration to get the agglomerative ion-exchange stationary phase. After optimizing the synthetic conditions, the new stationary phase was characterized by the techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The chromatographic column was packed by slurry method and applied in the analysis of SO42- with a conductivity detector. SO42- and other six common anions including F-, Cl-, NO2-, Br-, NO3-, PO43-, were separated and analyzed rapidly on the self-regulating chromatographic column within 8 min. The linear range was from 0.5 to 50 mg/L with correlation coefficient (r) of 0.9992. The LOD was 0.04 mg/L with S/N of 3. The relative standard deviations (RSDs, n=6) were 2.4% and 3.1% for the peak area and retention time, respectively. The recoveries were between 99.2% and 101.8%. The retention times of SO42- did not change significantly after long time use of the self-regulating chromatographic column. The self-regulating chromatographic column is suitable for the detection of SO42- in complex matrix samples.

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Application of ultra high performance liquid chromatography- mass spectrometry to metabolomics study of drug-induced hepatotoxicity LIU Xiaoyan, LIU Yanqiu, CHENG Mengchun, XIAO Hongbin 2015, 33 (7):  683-690.  DOI: 10.3724/SP.J.1123.2015.04007 Abstract ( 682 )   [Full Text(HTML)] () PDF (2821KB) ( 220 )   Drug-induced hepatotoxicity is a worldwide health issue. And diagnosing the injury in the early stage is still a challenge in clinic. In this study, pattern recognition analysis of the ultra high performance liquid chromatography-mass spectrometry (UPLC-MS) of hepatocytes HL7702 was performed to develop differential metabolites related to hepatotoxicity induced by hepatotoxicants, including carbon tetrachloride (CCl4), acetaminophen (APAP), emodin, aristolochic acid (AA) and triptolide. Hepatocytes injuries were induced by 48 h of treatment with CCl4 (4 mmol/L), APAP (6.5 mmol/L), emodin (14 μmol/L), AA (35 μmol/L) and triptolide (18 nmol/L), separately. Global metabolomics profiling, multivariate analysis and database searching were performed to discover common differential metabolites for live injury. The positive hepatoprotective drug, bifendate, was used to repair triptolide induced hepatocytes injury, and bifendate-induced changes of hepatotoxicity-related metabolites were investigated. In the results, fatty acid oxidation and cellular oxidative stress-related metabolites, including nicotinamide adenine dinucleotide and glutathione were significantly changed between the control and hepatotoxicant-treated groups, and after treatment with bifendate, those perturbed metabolites all partly returned to normal level. In conclusion, we discovered potential hepatotoxicity-related metabolites that could be used to evaluate hepatotoxicity induced by chemicals, drugs and traditional Chinese medicines. This study also proved that metabolomics is one of the effective tools to investigate drug-induced hepatotoxicity.

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Simultaneous qualitative and quantitative determination of seven anticoagulant rodenticides in whole blood and urine samples using on-line solid phase extraction with liquid chromatography-linear ion trap mass spectrometry HUANG Kejian, LU Minping, ZHOU Zhe, LIN Cuiwu, YANG Ning, LIU Xiaofeng, ZHU Dingji, LIANG Ping, QIAO Wentao, LI Hongsen, LI Lu, HUANG Xiaoqing 2015, 33 (7):  691-698.  DOI: 10.3724/SP.J.1123.2015.03010 Abstract ( 714 )   [Full Text(HTML)] () PDF (2319KB) ( 166 )   A new and sensitive analytical method has been developed for the simultaneous determination of seven anticoagulant rodenticides in whole blood and urine samples by liquid chromatography-linear ion trap mass spectrometry (LC-LIT/MS) with on-line solid phase extraction (on-line SPE). The samples were treated with acetonitrile, followed by dilution, centrifugation, and filtration. The resulting solution was injected into the LC system directly and processed by on-line SPE column for enrichment and purification. Separation was performed on a C18 column with mixed mobile phases of methanol and 0.02 mol/L ammonium acetate aqueous solution for gradient elution. The analytes were detected by the mass spectrometer with electrospray ionization (ESI) in negative mode. MS2 full scan signals of the target parent ions within the locked retention time window were recorded. Self-built database searching was performed for qualitative confirmation, and MS2 fragment ions with high sensitivity and specificity were selected for quantification. Simultaneous qualitative and quantitative analyses of the seven rodenticides were achieved in this way. Good linearities were obtained within the investigated mass concentration ranges of the seven rodenticides, with r2≥0.9958 in blood and r2≥0.9946 in urine. The LODs varied from 0.02 ng/mL to 1.00 ng/mL, and the LOQs varied from 0.10 ng/mL to 4.00 ng/mL. The recoveries at three spiked levels in blood and urine samples ranged from 81.0% to 113.9%, with RSDs of 0.1%-6.2% (n=6). The developed method is simple, sensitive, and can be used for the rapid detection and accurate quantification of the seven anticoagulant rodenticides in whole blood and urine samples.

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Determination of N6-(4-hydroxybenzyl) adenine riboside in rat plasma by ultra performance liquid chromatography- quadrupole time of flight mass spectrometry TANG Chunlan, WANG Li, CHENG Mengchun, LIU Xinxin, XIAO Hongbin 2015, 33 (7):  699-703.  DOI: 10.3724/SP.J.1123.2015.03017 Abstract ( 609 )   [Full Text(HTML)] () PDF (785KB) ( 117 )   An ultra performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC-QTOF-MS) method was developed and validated for the determination of N6-(4-hydroxybenzyl) adenine riboside and its pharmacokinetics in rat plasma. The chromatographic conditions were optimized. The separation was performed on an Agilent ZORBAX SB-C18 column(150 mm×3 mm, 1.8 μm) with a gradient elution of 0.2%(v/v) formic acid aqueous solution and acetonitrile as the mobile phases at a flow rate of 0.35 mL/min. The detection was accomplished in positive mode with electrospray ionization (ESI) by UPLC-QTOF-MS, and 6-benzylamino purine was used as the internal standard (IS). The results showed that the linear range of calibration curve was 0.625-160 ng/mL for N6-(4-hydroxybenzyl) adenine riboside in rat plasma with the correlation coefficient more than 0.99. The recoveries were 88.41%-108.26%. The limit of detection was 0.1 ng/mL. The intra-day and inter-day precisions (RSDs) were less than 6%, and intra-day and inter-day accuracies (REs, RE=(measured concentration-spiked concentration)/spiked concentration×100%) were less than ±15%. The method is rapid, sensitive and accurate for the quantitation of N6-(4-hydroxybenzyl) adenine riboside, which can be used for the study of pharmacokinetics of N6-(4-hydroxybenzyl) adenine riboside.

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Detection and identification of major metabolites of clorprenaline in swine urine using ultra-performance liquid chromatography- quadrupole time-of-flight mass spectrometry BI Yanfeng, WANG Yilin, YE Ni, SUN Lei, WANG Hejia, XU Shixin, XIAO Xilong 2015, 33 (7):  704-710.  DOI: 10.3724/SP.J.1123.2015.03007 Abstract ( 586 )   [Full Text(HTML)] () PDF (855KB) ( 147 )   This study was conducted to detect and identify the metabolites of clorprenaline in swine urine using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS), and the major metabolic pathways of clorprenaline were proposed. The swines were administered a single dose each of 10 mg/kg b. w. clorprenaline by oral gavage. The urine samples were collected before and after administration. After a simple preparation, the urine samples were analyzed using UPLC/Q-TOF MS. Combined with data processing techniques including extracted ion chromatography (EIC) and mass defect filtering (MDF), two phase Ⅰ and seven phase Ⅱ metabolites were detected in the urine samples collected 0-24 h after administration. The structures of detected metabolites were elucidated by comparing their characteristic product ions with those of the parent clorprenaline. Based on the identified metabolites, the metabolic pathways of clorprenaline included hydroxylation, glucuronidation and sulphate conjugates. Among those detected metabolites, hydroxylated-clorprenaline and its conjugates were responsible for over 60% of the total MS responses, much greater than those of clorprenaline, and were proposed as the primary metabolites in swine urine. This study can provide scientific basis for determining appropriate marker residues of clorprenaline, and facilitate to effectively control clorprenaline residues in animals.

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Determination of three coriaria lactones in honey by ultra high performance liquid chromatography- high resolution mass spectrometry YIN Yao, CHEN Huilan, CHEN Lei, BIE Xiaomei, DING Tao, ZHANG Xiaoyan, WU Bin, SHEN Chongyu, ZHANG Rui 2015, 33 (7):  711-714.  DOI: 10.3724/SP.J.1123.2015.02057 Abstract ( 830 )   [Full Text(HTML)] () PDF (760KB) ( 150 )   A method for the determination of three coriaria lactone residues in honey was developed using ultra high performance liquid chromatography-high resolution mass spectrometry. The honey samples were extracted with 0.2 mol/L phosphate buffer solution (pH=7.5), and the extracts were cleaned up with Waters HLB solid phase extraction cartridges. The extracted components were separated on a Phenomenex C18 column by gradient elution. The qualitative and quantitative analyses were operated under t-MS2 by high resolution mass spectrometry. The results showed that the limits of detection and quantification for the three coriaria lactones in a spiked blank honey were 0.05 mg/kg and 0.1 mg/kg, respectively. The recoveries of the three coriaria lactones spiked in blank honey samples at the levels of 0.1 to 0.5 mg/kg were 86.3%-95.6% with the RSDs of 3.0%-8.4%. The method was applied for the determination of the manuka honey from New Zealand, and tutin was detected in one of the samples. The results showed that the method is suitable for the determination of the three coriaria lactone residues in honey.

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Analysis of 17 cytokinins in rice by solid phase extraction purification and liquid chromatography- tandem mass spectrometry CAO Zhaoyun, MA Youning, MOU Renxiang, YU Shasha, CHEN Mingxue 2015, 33 (7):  715-721.  DOI: 10.3724/SP.J.1123.2015.03013 Abstract ( 658 )   [Full Text(HTML)] () PDF (1008KB) ( 209 )   A method was developed for the determination of 17 cytokinins in rice by solid phase extraction and liquid chromatography-tandem mass spectrometry. The rice samples were cryogenically ground under liquid nitrogen and extracted with methanol-water (80 : 20, v/v) at 4 ℃ for 16 h. The supernatant was purified on a column packed with polymer cation exchange resin (PCX). The samples were transported and eluted on an analytical column ZORBAX Extend-C18 (100 mm×2.1 mm, 1.8 μm) by methanol and 5 mmol/L ammonium formate aqueous solution. All the analytes were detected in selected reaction monitoring (SRM) mode under positive electrospray ionization (ESI+) and quantified by external standard method. The separation conditions were optimized in order to achieve the sufficient separation for the several isomers of cytokinins, such as trans-zeatin-7-glucoside (tZ7G), trans-zeatin-9-glucoside (tZ9G), and trans-zeatin-O-glucoside (tZOG). Moreover, the extraction efficiency of different extraction solvents and clean-up effects of PCX cartridge for each analyte were further investigated. The results showed that the correlation coefficients were not less than 0.9984 in the linear range, and the limits of detection were ranged from 0.01 to 0.05 ng/g. The mean recoveries of the 17 cytokinins at three spiked levels of 0.2, 1 and 5 ng/g were from 60.2% to 125.4% with the relative standard deviations (RSDs) of 5.4%-29.7% (n=6). Finally, five endogenous cytokinins were successfully quantified in real sample, and their contents were between 0.02 and 0.93 ng/g. It means that this method is reliable for quantitative analysis of cytokinins in rice.

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Simultaneous determination of ten antibiotics in pharmaceutical wastewater using ultra-high performance liquid chromatography-tandem mass spectrometry QIU Panzi, GUO Xinyan, WANG Na, KONG Xiangji, HE Hua 2015, 33 (7):  722-729.  DOI: 10.3724/SP.J.1123.2015.03039 Abstract ( 614 )   [Full Text(HTML)] () PDF (1396KB) ( 184 )   A simultaneous analytical method was established for ten selected antibiotics from three categories in pharmaceutical wastewater with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The water samples were enriched and cleaned-up by solid phase extraction cartridges. The types of solid phase extraction cartridges and eluents were optimized by comparing the recoveries of the analytes in water samples under different conditions. The target compounds were separated on an Agilent C18 column (75 mm×2.1 mm, 2.7 μm) with the mobile phases of acetonitrile and 0.2% (v/v) formic acid aqueous solution, and then determined by electrospray ionization mass spectrometry (ESI-MS). The results showed that the calibration curves were linear in the range of 0.1-1000 μg/L (r2 > 0.995). The limits of detection (LODs, S/N≥3) and the limits of quantification (LOQs, S/N≥10) of the ten compounds were 0.07-4.37 ng/L and 0.22-14.55 ng/L, respectively. The recovery experiments were performed with samples spiked in the range of 0.002-40 μg/L. The recoveries of the target compounds were in the range of 50.4%-114.1% (RSDs≤9.89%, n=3). Based on this analytical method, the raw and treated sewage samples from a pharmaceutical manufacturer wastewater treatment plant in Jiangsu Province were analyzed. Three compounds were detected in the samples from different sewage treatment units in the range of 0.46-1033.60 μg/L. It shows that the method is accurate, reliable, highly sensitive and can be used to analyze the water samples of pharmaceutical wastewater treatment plant containing aminoglycosides, spiramycin and fluoroquinolones antibiotics.

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Determination of 49 drugs and 5 metabolites in drinking water samples using ultra-high performance liquid chromatography- electrospray ionization tandem mass spectrometry WANG Shuo, ZHANG Xiangming, ZHANG Jing, SHAO Bing, LI Shuming 2015, 33 (7):  730-739.  DOI: 10.3724/SP.J.1123.2015.03004 Abstract ( 518 )   [Full Text(HTML)] () PDF (946KB) ( 130 )   A method for the determination of 54 drugs in drinking water samples was developed by using ultra-high performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI MS/MS). The target drugs in drinking water samples were enriched and cleaned-up by HLB solid-phase extraction (SPE) cartridges and then eluted with 5 mL methanol. The elute was collected, concentrated under a gentle stream of nitrogen gas, diluted with 0.4 mL 0.1% formic acid solution, and analyzed by UPLC-ESI MS/MS. The separation of the 54 drugs was performed on an ACQUITY UPLCTMBEH C18 column using mobile phases of 0.1% formic acid and methanol by gradient elution. The multiple reaction monitoring (MRM) mode was employed in mass spectrometry acquisition. The matrix-matched external standard calibration was used for quantitation. The results showed that the average recoveries of the drugs in ground water, tap water and surface water were 58.7%-104.4%, 53.1%-109.5%, and 50.7%-118.8%, respectively, and the corresponding relative standard deviations (RSD, n=6) were 0.3%-12.8%, 1.0%-15.5%, and 0.4%-19.3%, respectively. The method quantification limits (MQL) for target compounds were in the range of 0.002-5.000 ng/L. The developed method was applied to analyze the water samples from Beijing. The results showed that 26 drugs were detected in ground water samples.

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Simultaneous determination of 13 organic pollutants in water samples by high performance liquid chromatography- tandem mass spectrometry LUO Birong, QIAN Shu, XIE Zhenwei, YAO Huan, XIONG Jie, ZHAO Hong 2015, 33 (7):  740-745.  DOI: 10.3724/SP.J.1123.2015.03005 Abstract ( 663 )   [Full Text(HTML)] () PDF (789KB) ( 152 )   On the basis of environmental quality standards for surface water, a sensitive and simple method was developed for the simultaneous determination of 13 organic pollutants, including dimethoate, dichlorvos, trichlorfon, parathion, methyl parathion, malathion, demeton, acrylamide, aniline, benzidine, carbaryl, Microcystin-LR and atrazine in water samples by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with direct injection. The water samples were filtered through 0.22 μm of microfiltration membrane. With methanol-0.01% formic acid as mobile phase, the separation was performed on a Kromasil 100-5 C18 column (150 mm×2.1 mm, 5 μm) in gradient elution. The flow rate was 0.5 mL/min. The column temperature was 40 ℃. The samples were detected by multiple reaction monitoring (MRM) mode with positive electro spray ionization. The organic pollutants were quantified by external standard method. The calibration curves of the organic pollutants show good linearity in suitable ranges with correlation coefficients (r) over 0.9995. The detection limits of organic pollutants in samples ranged from 0.02 μg/L to 0.1 μg/L. The relative standard deviations of organic pollutants were 0.5%-5.0% (n=6). The average recoveries of the 13 organic pollutants spiked in water samples ranged from 81.2% to 112%. The method has been proven to be sensitive, rapid and with little interference. It is suitable for the determination of the 13 organic pollutants simultaneously in the surface and underground waters.

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Determination of 12 flavonoids in tobacco leaves using ultra-high performance liquid chromatography- tandem mass spectrometry LI Yong, LIN Qian, PANG Tao, SHI Junli 2015, 33 (7):  746-752.  DOI: 10.3724/SP.J.1123.2015.03001 Abstract ( 710 )   [Full Text(HTML)] () PDF (828KB) ( 206 )   Flavonoids are very important secondary metabolites for tobacco plants. They are also considered as important flavor precursors for cigarettes. A method of ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the simultaneous determination of 12 flavonoids in tobacco leaves. The developed method determined 10 more flavonoids compared to the traditional method. A solution of methanol-water-chloroform (5 : 2 : 2, v/v/v) was used to extract the flavonoids from tobacco leaves and remove the pigment. Instrument analysis using the UPLC-MS/MS was completed in 13 min. The method validation was performed, and the results showed that the linear correlation coefficients (r2) of all the 12 flavonoids were more than 0.99. The limits of detection and the limits of quantification were in the range of 0.3-100 μg/L and 1.2-400 μg/L, respectively. Intra-day and Inter-day reproducibilities were in the range of 3.5%-7.4% and 5.2%-11.4%, respectively. The recoveries were 81.2%-111.9%. The established method was successfully used to analyze the flavonoids of tobacco leaves of 11 varieties. Significant concentration differences of the flavonoids were found among the determined varieties. Furthermore, significant positive correlation among the flavonoids with similar chemical structures (aglycones and their related glycosides, glycosides with the same aglycone, and similar aglycones) was found using the acquired data.

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Determination of five triazine herbicides in infant milk powder by high performance liquid chromatography coupled with ionic liquid-based homogeneous liquid-liquid microextraction ZHANG Liyuan, YAO Di, LI Na, ZHANG Hanqi, YU Aimin 2015, 33 (7):  753-758.  DOI: 10.3724/SP.J.1123.2015.03014 Abstract ( 488 )   [Full Text(HTML)] () PDF (1591KB) ( 110 )   A high performance liquid chromatography coupled with homogeneous liquid-liquid microextraction was developed for the determination of five triazine herbicides in infant milk powders. The ionic liquid was used as microextraction solvent. The separation of the herbicides was performed on an Eclipse XDB-C18 column using acetonitrile and water as mobile phases in gradient mode. The effects of homogeneous liquid-liquid extraction conditions on the experimental results were investigated in detail. Under the optimized experimental conditions, the calibration curves for determining the analytes were linear and the correlation coefficients were ≥0.9992. The limits of detection for cyanazine, desmetryn, terbumeton, terbuthylazine and dimethametryn were 12.1, 13.8, 11.8, 14.6 and 13.7 μg/kg, respectively. The recoveries of the analytes spiked in four infant milk powders ranged from 92.2% to 103.2% and the relative standard deviations were lower than 6%. This method is sensitive, simple, and suitable for the determination of triazine herbicides in milk powder samples.

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Ion-pair chromatography-indirect ultraviolet detection for determination of tetraethyl ammonium using a monolithic column and a packed column ZOU Chunmiao, ZHANG Xiaodong, YU Hong, GUAN Chao, WANG Miaoyu 2015, 33 (7):  759-764.  DOI: 10.3724/SP.J.1123.2015.03043 Abstract ( 560 )   [Full Text(HTML)] () PDF (811KB) ( 203 )   Two methods were developed for the determination of tetraethyl ammonium by ion-pair chromatography-indirect ultraviolet detection using a monolithic column and a packed column with ionic liquid as additive in mobile phase. Chromatographic separations were performed on a monolithic column and a packed column both on reversed phase using imidazolium ionic liquid aqueous solution-ion-pair reagent-organic solvent as mobile phase. The effects of the background ultraviolet absorption reagent, detection wavelength, ion-pair reagent, organic solvent, column temperature and flow rate on the determination of tetraethyl ammonium were investigated. The difference between the two chromatographic columns was compared and the retention rules were discussed. Under the optimized chromatographic conditions, for tetraethyl ammonium on monolithic column and packed column, the retention times were 2.40 and 3.02 min; the detection limits (S/N=3), 0.04 and 0.07 mg/L; the RSDs (n=5) for peak areas, 0.16% and 0.11%; and the RSDs (n=5) for retention times, 0.02% and 0.01%, respectively. The two methods have been successfully applied to the determination of tetraethyl ammonium ionic liquids synthesized by laboratory. The recoveries of the tetraethyl ammonium after spiking were 98.2% and 99.1%, respectively. The two methods can meet the requirements for the quantitative analysis of tetraethyl ammonium.

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A novel liquid chromatographic method with fluorescence detection for quantitation of tadalafil and dapoxetine hydrochloride in pharmaceutical dosage form and human plasma MAHA Hegazy, AMIRA Kessiba, MOHAMED Abdelkawy, AHMED EMAD El Gindy 2015, 33 (7):  765-770.  DOI: 10.3724/SP.J.1123.2015.02063 Abstract ( 732 )   [Full Text(HTML)] () PDF (610KB) ( 178 )   Tadalafil (TAD) and dapoxetine HCl (DAP) are recently co-formulated and both show native fluorescence. Therefore, a novel, accurate, specific and sensitive reversed-phase high performance liquid chromatographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard (IS). Separation was achieved using isocratic elution within 7.0 min on C18 column and acetonitrile-0.15% triethylamine (40 : 60, v/v; pH 4) as a mobile phase. The flow rate was 1.0 mL/min and the detection was time-programmed at 330, 410 and 370 nm for TAD, DAP and IS, respectively, after excitation at 236 nm. The linear ranges from 0.01 to 30.00 μg/mL for each drug with the limits of detection of 4.20 and 7.20 ng/mL for TAD and DAP, respectively. The method was validated in accordance to the International Conference on Harmonization (ICH) guidelines and was successfully applied to spiked human plasma with mean recoveries of 98.17% and 98.83% for TAD and DAP respectively.

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Determination of the contents of vitamin C and its derivatives in cosmetics by high performance liquid chromatography CHEN Peijin, YAN Zhi, TU Xiaoke, XIAO Feng, LIANG Hong 2015, 33 (7):  771-776.  DOI: 10.3724/SP.J.1123.2015.02060 Abstract ( 1702 )   [Full Text(HTML)] () PDF (796KB) ( 594 )   A method has established for the detection of vitamin C (VC) and its derivatives (ascorbyl glucoside, AA-2G; magnesium ascorbyl phosphate, AA-2P; ascorbic acid ethyl ether, Only VCE) in cosmetics by high performance liquid chromatography (HPLC). Low fat cosmetic samples such as make-up water and lotion were extracted directly with 30 mL 0.02 mol/L potassium dihydrogen phosphate solution (pH 3.0). High fat cosmetic samples such as face cream and gel were well dispersed with 1.0 mL dichloromethane first, then extracted with 25 mL 0.02 mol/L potassium dihydrogen phosphate solution (pH 3.0). The sample solution was centrifuged with a speed of 12000 r/min, then filtered through a 0.22 μm syringe filter. The filtrate was analyzed on a column of YMC-Triart C18 (250 mm×4.6 mm, 5 μm) using 0.02 mol/L potassium dihydrogen phosphate solution (pH 3.0) and methanol as mobile phases with a flow rate of 1.0 mL/min. The temperature of the column was 25 ℃ and the detection wavelength was 250 nm. The standard working curves of the four analytes had good linear relationship (r2 > 0.9999). The detection limits of the four analytes were 0.04-0.08 g/kg (S/N=10). The recoveries were 95.6%-101.0% with the relative standard deviations of 0.62%-3.0% at the spiked levels of 0.25-5.0 g/kg. This method is a simple, rapid, exact and reliable for the determination of the contents of vitamin C and its derivatives in cosmetics.

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Analysis of alkaline CuO degradation products of acid detergent fiber from tobacco leaves by using liquid chromatography HAO Weiqiang, WANG Leijun, WU Shun, YUE Bangyi, CHEN Qiang, ZHANG Peipei 2015, 33 (7):  777-782.  DOI: 10.3724/SP.J.1123.2015.01043 Abstract ( 516 )   [Full Text(HTML)] () PDF (823KB) ( 163 )   The acid detergent fiber (ADF) from tobacco leaves was obtained by treating the sample with petroleum ether-ethanol (6 : 4, v/v), 30 g/L sodium dodecylsulfate and 0.5 mol/L sulphuric acid containing 20 g/L hexadecyl trimethyl ammonium bromide successively. The ADF was degraded by the alkaline CuO oxidation procedure. In this work, six samples of ADF degradation products from tobacco leaves were prepared. The samples were analyzed by using gradient liquid chromatography (LC) where an Ultimate XB C18 column was used as stationary phase, with a mixture of methanol and water as mobile phase, at a column temperature of 35 ℃ and a flow rate of 0.8 mL/min. Dual wavelengths of 280 nm and 320 nm were chosen for the detection. It was found that there were four characteristic peaks for the ADF degradation products. By taking these peaks as research object, the optimum time for the degradation was found to be 5 h and the sample solution could be kept stable within 7 days. The established method may provide a new approach for the studies of the differences between lignin composition in different tobacco leaves and the relationship between lignin content and the smoking quality of tobacco leaves.