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Chinese Journal of Chromatography
2012, Vol. 30, No. 02
Online: 28 February 2012

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Recent advances in the application of high performance liquid chromatography for the analysis of carbohydrates DAI Jun 2012, 30 (02):  113-115.  DOI: 10.3724/SP.J.1123.2012.02023 Abstract ( 1868 )   [Full Text(HTML)] () PDF (89KB) ( 762 )

Reviews

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Application of capillary electrophoresis in analysis of intact mammalian cells ZHANG Lu, QU Feng*, LOU Beilei 2012, 30 (02):  116-122.  DOI: 10.3724/SP.J.1123.2011.11011 Abstract ( 1784 )   [Full Text(HTML)] () PDF (174KB) ( 342 )   Cell is the basic structural and functional unit of human body. The research of cells’ structure, function and behavior is very important. Capillary electrophoresis (CE) is a powerful tool for the separation and analysis, the application of which in cell analysis has progressed significantly. In this paper, the developments of CE applied in the intact mammalian cell analysis are reviewed, which consist of cell population and single cell analysis. The erythrocyte, boar sperm, HeLa cells, SH-SY5Y cells, Caco-2 cells, K562 cells and rat cerebellar granule cells are involved in this review. The methods and conditions for the intact mammalian cell analysis are summarized. In addition, the problems caused by the breakage, aggregation, sedimentation, adsorption and electrophoretic heterogeneity of the cell in the intact mammalian cell analysis by CE are discussed, and the corresponding solutions are introduced. Also, the future research trends are presented. Forty nine papers in all are reviewed.

Communications

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Hepatotoxicity of perfluorooctanoic acid in human hepatocytes using metabonomics PENG Siyuan1, YAN Lijuan2, ZHANG Jie1*, SHEN Heqing1* 2012, 30 (02):  123-127.  DOI: 10.3724/SP.J.1123.2011.12059 Abstract ( 1957 )   [Full Text(HTML)] () PDF (182KB) ( 528 )   Ultra performance liquid chromatography coupled to orthogonal acceleration time-of-flight mass spectrometry was used to study metabolic profiling of L-02 human liver cell exposed to different doses of perfluorooctanoic acid (PFOA) for 72 h. Principle component analysis method was used for group differentiation and biomarker screening. Dose-dependent distribution of the treated samples with different doses could be observed in scores plots obtained under both positive and negative ionization modes. Furthermore, eighteen metabolites were identified as potential biomarkers which were closely related with the toxicity of PFOA. The identified biomarkers included carnitine and acylcarnitines, nucleosides and nucleoside conjugates, amino acids and amino acid conjugates etc. Among them, significant changes of carnitine and its metabolites were observed in the control group and dose groups, which play an important role in fatty acid metabolism. Meanwhile, some genes involved in cholesterol biosynthesis were upregulated dramatically using gene microarray analysis. The disturbance of cholesterol biosynthesis could have adverse impact on fatty acid metabolism, consequently induce the decrease of carnitine and increase of acylcarnitines in treated groups. Additionally, purine metabolism, tricarboxylic acid cycle, glycosphingolipid metabolism and amino acid metabolism may also be involved in the toxic response to PFOA.

Articles

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Characterization of aromatic hydrocarbons in heavy gas oil using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry GUO Kun, ZHOU Jian*, LIU Zelong 2012, 30 (02):  128-134.  DOI: 10.3724/SP.J.1123.2011.09015 Abstract ( 1731 )   [Full Text(HTML)] () PDF (521KB) ( 505 )   An analytical method for separating and identifying the aromatic hydrocarbons in heavy gas oil using comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (TOF MS) was established. The two-dimensional distribution by ring number of the aromatic hydrocarbons was obtained. Besides phenanthrene and methylphenanthrene, many other polycyclic aromatic hydrocarbons (PAHs) such as pyrene and benzo［a］anthracene were identified by using the retention times, standard mass spectra or literature reports. The method was successfully applied to the hydrotreating process of heavy gas oil and the hydrotreated products of phenanthrene, pyrene were identified. This method provided technical support for the characterization of aromatic hydrocarbons in heavy gas oil and the investigation of hydrogenation mechanism of polycyclic aromatic hydrocarbons. Compared with the conventional method, gas chromatography coupled to mass spectrometry (GC-MS), the GC×GC-TOF MS method illustrated the obvious advantages for heavy gas oil analysis.

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Determination of five synthetic musks in perfume by headspace solid-phase microextraction and gas chromatography-mass spectrometry WANG Guannan1, TANG Hua2, CHEN Dazhou2, FENG Jie1, LI Lei1* 2012, 30 (02):  135-140.  DOI: 10.3724/SP.J.1123.2011.10018 Abstract ( 2477 )   [Full Text(HTML)] () PDF (249KB) ( 475 )   A method for headspace solid-phase microextraction(HS-SPME), followed by gas chromatography-mass spectrometry (GC-MS) analysis was established for the determination of five commonly used synthetic musks in perfume. Two polycyclic musks (celestolide and tonalide) and three nitro musks (musk ambrette, musk xylene and musk ketone) were used as analytes in the optimization of the analytical method. Six parameters, such as the extraction temperature, equilibrium time, extraction time, desorption time, injector temperature and solution of salting out, were optimized by exposing the 65 μm polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber to the headspace of magnetically stirred (600 r/min) sample. According to the results of the optimization experiments, the following conclusion can be drawn: The water-diluted sample in a 10 mL headspace-vial was efficiently extracted for 20 min after the system was equilibrated for 3 min at 60 ℃. After extraction, the fiber was immediately inserted into the GC injector and desorbed at 250 ℃ for 3 min. The spiked recoveries were in the range of 82.0%~103.3% and the relative standard deviations (RSDs) were between 1.8% and 9.4%. Meanwhile, the limits of detection (LODs) ranged from 0.6 ng/g to 2.1 ng/g. This method is characterized by rapidity, high sensitivity, good linearity and repeatability for all the target compounds. It is applicable to the analysis of synthetic musks in perfumes.

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A novel solid phase extraction column combined with ultra performance liquid chromatography/tandem mass spectrometry for selective enrichment and determination of clenbuterol in pork MENG Wenying1, GUO Zhimou2, SHEN Weijian3, SHEN Chongyu3, WU Bin3, LIU Yanming4, ZHANG Feifang1*, LIANG Xinmiao1,2 2012, 30 (02):  141-145.  DOI: 10.3724/SP.J.1123.2011.09038 Abstract ( 2028 )   [Full Text(HTML)] () PDF (205KB) ( 426 )   A simple and efficient method based on a novel solid phase extraction (SPE) cartridge and ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the determination of clenbuterol residue in pork. The minced pork sample was ultrasonically extracted by 5% (v/v) perchloric acid and centrifuged at 10000 r/min for 15 min, then the supernatant was purified by an SMCX cartridge, which is a novel SPE column based on homemade silica matrix with two mixed modes of reversed-phase and strong cation exchange, for the selective enrichment and purification of the analyte. The linear range of the method was 0.25~50 μg/kg with a correlation coefficient of 0.9982. The average recoveries ranged from 62.2% to 72.0% at the three spiked levels of 1.25, 12.5 and 50 μg/kg with the relative standard deviations (RSDs) between 4.2% and 6.1%. The limit of detection (S/N=3) was 0.05 μg/kg. The method is simple, fast and can be extended to enrich and determine β-agonist drugs.

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Evaluation of QuEChERS methods for the analysis of 66 organophosphorus pesticide residues in vegetables by liquid chromatography-tandem mass spectrometry WANG Lianzhu1*, ZHOU Yu2, CHEN Yong1, WANG Ruilong1, LIN Zixu1, LIN Dejuan3, ZHENG Shaohui1 2012, 30 (02):  146-153.  DOI: 10.3724/SP.J.1123.2011.10012 Abstract ( 2681 )   [Full Text(HTML)] () PDF (305KB) ( 701 )   A comparison was made between the two versions of QuEChERS sample preparation method for the extraction of 66 organophosphorus pesticides (OPPS) in vegetables. The two QuEChERS methods were the original method without buffer published in 2003, and the AOAC Official Method 2007.01 with acetate buffer. The adsorption behaviors of primary secondary amine (PSA) sorbent and C18 sorbent on the OPPS were studied. The method of after-extraction addition was used to evaluate matrix effects for OPPS in matrix of broccoli, tomato, green soybean, radish and shallot during liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. As a result, the QuEChERS method with acetate buffer gave higher and more consistent recoveries for some of OPPS. The PSA sorbent and C18 sorbent can adsorb dibrom, so the QuEChERS method was not suitable for the analysis of dibrom. The maximum matrix effects were in the extracts of broccoli during LC-MS/MS analysis. In this article, OPPS were extracted using the QuEChERS method with acetate buffer, and analysed by LC-MS/MS under the optimized conditions with monitoring 132 MS/MS transitions of precursor ions (two for each pesticide) in one single run. Recoveries for all but dibrom at fortification levels of 10, 40, 80 μg/kg in broccoli, tomato, green soybean, radish and shallot ranged from 55% to 122% with relative standard deviations of 1.6%~18%. The limits of quantification (S/N≥10) were 0.1~8 μg/kg. Based on these results, the analytical method was proven to be highly efficient, robust and sensitive, and suitable for the monitoring of the maximum residue limits (MRLs) of 66 OPPS in vegetables.

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Determination of mitomycin C in rabbit plasma by ultra-high performance liquid chromatography-tandem mass spectrometry TANG Yao1, ZHANG Shuangqing1, LI Xiang2, SUN Xu1, WEN Nie1, YU Min1, PENG Lili3, LI Jinrang3, LI Zuogang1*, LI Bo1 2012, 30 (02):  154-159.  DOI: 10.3724/SP.J.1123.2011.10034 Abstract ( 2274 )   [Full Text(HTML)] () PDF (222KB) ( 394 )   An ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the determination of mitomycin C (MMC) in rabbit plasma was established. The blank rabbit plasma sample solutions added with mitomycin C and triamcinolone acetonide (internal standard, IS) were prepared. The solutions containing MMC and IS were extracted from the plasma with ethyl acetate using liquid-liquid extraction method. A Hypersil Gold C18 column (50 mm×2.1 mm, 1.9 μm) was employed and the column temperature was set at 35 ℃. The isocratic elution of methanol and 0.1% (v/v) formic acid aqueous solution as mobile phase was performed at a flow rate of 0.2 mL/min, and a rapid separation was completed within 3 min. The electrospray was operated in the positive ionization mode and the MMC and IS were identified in selected reaction monitoring (SRM) mode. The monitoring ions of MMC and IS were m/z 335.2→242.2 and m/z 435.2→397.3/415.2, respectively, which were used to qualify and quantify the targets by the method of matrix-matched standard solution. The calibration curve showed good linearity within the mass concentrations of 1 to 1000 μg/L (r=0.9978, weighting: 1/x2). The limit of detection (S/N=3) was 0.2 μg/L. The recoveries were from 85% to 115% at the spiked levels of 1, 5, 100 and 800 μg/L, and the relative standard deviations (RSDs) of intra- and inter-day were both less than 15%. The method can meet the determination requirements of biological samples, and can be used for the determination of mitomycin C in rabbit plasma after the administration of mitomycin C. The method is selective, sensitive, convenient, rapid and reproducible in the determination of mitomycin C, and also can be used for the pharmacokinetics research of mitomycin C in plasma.

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Determination of five coumarins in toys by high performance liquid chromatography-tandem mass spectrometry YANG Rongjing*, WEI Biwen, GAO Huan, YU Wenjia 2012, 30 (02):  160-164.  DOI: 10.3724/SP.J.1123.2011.10001 Abstract ( 2061 )   [Full Text(HTML)] () PDF (166KB) ( 345 )   A rapid analytical method for the determination of five coumarins （coumarin, 7-methoxycoumarin, dihydrocoumarin, 7-methyl coumarin and 7-ethoxy-4-methyl coumarin） in toys by high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） has been developed. After ultrasonic extraction in tetrahydrofuran, the samples were analyzed by HPLC-MS/MS in multi-reaction monitoring （MRM） mode. Acetonitrile and 0.1% acetic acid were used as the mobile phases with gradient elution. The linear ranges of calibration curves were 10~1000 μg/L, and the limits of quantification （LOQ） （S/N>10） were 2.0 μg/L for all the analytes, except that the LOQ for dihydrocoumarin was 5.0 μg/L. The recoveries of the five coumarins spiked in three types of samples were in the ranges of 93.2%~105.8%, 97.3%~ 103.2% and 96.8%~102.9%, with the relative standard deviations in the ranges of 4.35%~8.27%, 3.65%~6.73% and 4.03%~6.45%, respectively. The method was applied in the determination of 12 toy samples. The five analytes were found in 9 samples, and in some cases, the presence of quite high concentrations of these coumarins in the toys should be a matter of concern.

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Industrial preparative chromatography purification of 10-deacetylpaclitaxel, the enzymatic product of 7-xylosyl-10-deacetylpaclitaxel LIU Xingbao, LUAN Hongwei, GE Guangbo, HOU Kun, DU Xunfu, YANG Ling* 2012, 30 (02):  165-169.  DOI: 10.3724/SP.J.1123.2011.10021 Abstract ( 2438 )   [Full Text(HTML)] () PDF (204KB) ( 497 )   A scheme for industrial preparative chromatography purification of 10-deacetylpaclitaxel (10-DAP), the semi-synthesized precursor of anticancer drug paclitaxel was developed. 7-Xylosyl-10-deacetylpaclitaxel (10-DAXP) is the most abundant constitute in the needles of Taxus Chinensis, a specific yew species distributed in China. 10-DAXP has been recognized as a good material to convert into 10-DAP, the most ideal precursor of paclitaxel. The partially purified extract from yew needles which mainly contains 10-DAXP (＞60%) and other two minor 7-xylosyl-10-deacetyltaxanes including 7-xylosyl-10-deacetylcephalomannine (10-DAXC) and 7-xylosyl-10-deacetylpaclitaxel C (10-DAXP C), was used as the starting material. The total scheme can be divided into four steps. Firstly, the starting material was hydrolyzed by β-xylosidase to remove the C-7 xylosyl group completely; and then the hydrolyzed products mainly containing 10-DAP were eluted on a column packed with resin to get crude 10-DAP (with the purity of 20.5%) with high yield (96.3%). The crude 10-DAP was purified by a column packed with normal phase, and then by a reversed-phase preparative chromatography with ODS as the solid phase. After these two steps, the purity of the aim product 10-DAP was 96% with the overall yield of 79.7%. This novel scheme was suitable for large-scale purification of 10-DAP from 10-DAXP.

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Establishment of retention time-dependent intelligent selected reaction monitoring mass spectrometric method and its application MAO Xinli1,2, WEI Junying2, NIU Ming2, ZHOU Lianqi2, WANG Xueying1, TONG Wei2, QIN Weijie2, ZHANG Yangjun2*, QIAN Xiaohong2* 2012, 30 (02):  170-177.  DOI: 10.3724/SP.J.1123.2011.11020 Abstract ( 1854 )   [Full Text(HTML)] () PDF (324KB) ( 314 )   A method of liquid chromatographic retention time-dependent intelligent selected reaction monitoring mass spectrometry (iSRM MS) was established for the identification of targeted proteome, and was compared in detail with the method without liquid chromatographic retention time-dependent iSRM MS in the analysis results of different samples, such as the peptide mixtures from bovine serum albumin, six standard proteins or Thermoanaerobacter tengcongensis extract digested by trypsin. The results showed that the throughput of the identified peptides and the proteins was evidently increased with the method of liquid chromatographic retention time-dependent iSRM MS, especially in the complex sample such as Thermoanaerobacter tengcongensis extract. The coverage of the identified peptides and proteins from Thermoanaerobacter tengcongensis extract was reached 89.62% and 92.41% of the number of targeted peptides and proteins respectively. Higher sensitivity and reproducibility were also obtained. In addition, peptides with the same m/z but different retention times could be identified accurately when the method was used. With the higher throughput, better sensitivity and excellent reproducibility, the method of liquid chromatographic retention time-dependent iSRM MS can play an important role in the identification of targeted proteomes of complex biological samples in the future.

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Separation and quantitative analysis of the composition of low molecular weight sulfated polysaccharides by size exclusion chromatography WU Yanfang1, LI Xiaoge2, CHE Tiejun3, ZHU Zhijia1, KANG Jingwu2* 2012, 30 (02):  173-183.  DOI: 10.3724/SP.J.1123.2011.10005 Abstract ( 1871 )   [Full Text(HTML)] () PDF (223KB) ( 453 )   As the composition of low molecular weight sulfated polysaccharides is very complex, the quantitative analysis of their compositions is very important for understanding their bioactivity and the purpose of the quality control. A method was developed for the separation and quantitative analysis of the composition of low molecular weight sulfated polysaccharides. The effects of the parameters, such as the mobile phase constitution including ionic strength and pH, column length and temperature, flow rate of the mobile phase on the separation were systematically investigated. The obtained optimal conditions were as follows: two TSK-GEL G2000 SWxl columns (300 mm×7.8 mm) coupled together; mobile phase, 100 mmol/L Na2HPO4-NaH2PO4 (pH 7.0); flow rate, 0.5 mL/min; column temperature, 35 ℃; injection volume, 5 μL; sample concentration, 10 g/L. The method was validated in terms of its reproducibility and robustness. Under the optimized chromatographic separation conditions, each composition of the low molecular weight sulfated polysaccharide can be clearly separated, and their distribution ratios were quantitatively analyzed. The composition profilings of the samples from United States pharmacopoeia (USP), the two commercial available samples and two home-made samples were quantitatively compared. The method can be used for the quality control of the drugs based on low molecular weight sulfated polysaccharides.

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Determination of theanine and γ-aminobutyric acid in tea by high performance liquid chromatography with precolumn derivatization Xiufang, ZHANG Shikang, ZHU Yuejin 2012, 30 (02):  184-189.  DOI: 10.3724/SP.J.1123.2011.10037 Abstract ( 3399 )   [Full Text(HTML)] () PDF (258KB) ( 571 )   A method of precolumn derivatization-high performance liquid chromatography (HPLC) for the determination of theanine and γ-aminobutyric acid (GABA) in tea was established. o-Phthalaldehyde (OPA) and N-acetyl-L-cysteine (NAC) were chosen as the derivatization reagents. The effects of teapolyphenol (Tp), proline (Pro) and Vitamin C (Vc) on derivatization yields were investigated. The results indicated that Vc not only stabilized the stock solution of OPA, but also enhanced the yield of GABA derivative. However, the yield of theanine derivative was less affected. The HPLC separation system was also optimized. The resolution of the derivatives was improved by adjusting the pH value and phosphate-citric buffer concentration of the mobile phase. The limits of detection (LODs) for GABA and theanine were 3.01×10~5mmol/L and 7.98×10~5mmol/L, and the limits of quantification (LOQs) were 9.99×10~5mmol/L and 2.658×10~4mmol/L, respectively. The linear ranges of GABA and theanine were 0.01~0.4 mmol/L with the correlation coefficient of 0.996 and 0.05~0.8 mmol/L with the correlation coefficient of 0.995, respectively. The main recoveries for GABA and theanine in green tea, Oolong tea, and black tea, ranged from 99.29% to 119.60% and from 62.88% to 141.06% respectively. The method with simple procedure and efficient separation was proved to be suitable for the determination of GABA and theanine in tea.

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Simultaneous determination of 9 ultraviolet stabilizers in food plastic packaging materials by solid phase extraction-high performance liquid chromatography ZHANG Juzhou*, LI Jing, SHAO Dongliang, YAO Bangben, JIANG Junshu 2012, 30 (02):  190-195.  DOI: 10.3724/SP.J.1123.2011.10002 Abstract ( 1860 )   [Full Text(HTML)] () PDF (217KB) ( 459 )   An effective high performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of 9 ultraviolet stabilizers in food plastic packaging materials. The food packaging samples were firstly extracted by methanol-ethyl acetate, and then purified by a C18 solid-phase extraction (SPE) column. The target compounds were separated on a ZORBAX SB-C18 column (250 mm×4.6 mm, 5 μm) in gradient elution mode using methanol and water as mobile phases. The detection wavelength was at 310 nm. The linear plots of the nine ultraviolet stabilizers were obtained between 0.2 and 10 mg/L, with the correlation coefficients of above 0.999 for the nine ultraviolet stabilizers. The limits of detection for this method were in the range from 0.05 to 0.1 mg/L. The recoveries spiked in commercial food plastic packaging materials were in the range of 70.2%~89.0% with the relative standard deviations of 0.4%~4.5%. The results indicated that the method is simple, accurate, and suitable for the simultaneous determination of the nine ultraviolet stabilizers in food plastic packaging materials.

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Study of chemical kinetics between pyrroloquinoline quinine and D-serine in body by ion-pair liquid chromatography ZHOU Xingqin*, QIN Xiaofeng, ZHANG Jiankang, CAO Guoxian 2012, 30 (02):  196-200.  DOI: 10.3724/SP.J.1123.2011.09040 Abstract ( 1574 )   [Full Text(HTML)] () PDF (194KB) ( 320 )   As a new neurotransmitter present in the glial cells, D-serine (DSer) plays an important role in central nervous system diseases. Pyrroloquinoline quinine (PQQ) can promote the production of the nerve growth factor and has a protective effect on nerve injuries. The chemical kinetics of PQQ and DSer was studied by determining the free contents of PQQ using ion-pair liquid chromatography (LC), so it can provide important information for the mechanisms of PQQ in the regulation of neurotransmitter. The PQQ and the production of the incubation were separated on an Amethyst C18-P column using tetrabutylammonium bromide as ion-pair reagent. The average recoveries were between 94.2% and 99.3%, and the relative standard deviations were between 1.05% and 2.03%. The average rate constants (K) of PQQ with DSer were 0.032, 0.07 and 0.17 h~1 at 25, 37 and 50 ℃, respectively. The average activation energy (Ea) was 54.7 kJ/mol. The values of half life (t1/2) were 22.0, 9.8 and 3.99 h at 25, 37 and 50 ℃, respectively. The results showed that PQQ can regulate the balance of DSer in the brain. The method is simple and reliable.

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LLow-density solvent-based solvent demulsification dispersive liquid-liquid microextraction combined with gas chromatography for determination of polycyclic aromatic hydrocarbons in water samples ZHU Benqiong, CHEN Hao, LI Shengqing* 2012, 30 (02):  201-206.  DOI: 10.3724/SP.J.1123.2011.10011 Abstract ( 2423 )   [Full Text(HTML)] () PDF (281KB) ( 543 )   A novel method of low-density solvent-based solvent demulsification dispersive liquid-liquid microextraction (SD-DLLME) was developed for the determination of eight polycyclic aromatic hydrocarbons (PAHs) in water samples by gas chromatography-flame ionization detection (GC-FID). Conventional DLLME methods usually employ organic solvents heavier than water as the extraction solvents and achieve the phase separation through centrifugation. On the contrary, in this proposed extraction procedure, a mixture of low-density extraction solvent (toluene) and dispersive solvent (acetone) was injected into the aqueous sample solution to form an emulsion. A demulsification solvent (acetonitrile) was then injected into the aqueous solution to break up the emulsion, which turned clear quickly and was separated into two layers. The upper layer (toluene) was collected and analyzed by GC. No centrifugation was required in this procedure. Factors affecting the extraction efficiency such as the type and volume of dispersive solvent, extraction solvent and de-emulsifier were investigated in detail. Under the optimized conditions, the proposed method provided a good linearity in the range of 20~500 μg/L (r2=0.9942 ~ 0.9999). The limits of detection (S/N=3) were in the range of 0.52~5.11 μg/L. The relative standard deviations (RSDs) for the determination of 40 μg/L PAHs were in the range of 2.2%~13.6% (n=5). The proposed method is fast, efficient and convenient. It has been successfully applied to the determination of PAHs in natural water samples with the spiked recoveries of 80.2%~115.1%.

Technical Notes

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Determination of cholesterol in drainage oil by solid phase extraction-gas chromatography-mass spectrometry ZHOU Yongsheng1, LUO Shiping1, KONG Yong1,2* 2012, 30 (02):  207-210.  Abstract ( 2250 )   [Full Text(HTML)] () PDF (151KB) ( 373 )   An effective method was developed for the determination of cholesterol in drainage oil by solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS). Firstly, the samples were purified by SPE on a column packed with silica. An extraction yield of 97% was obtained when a 20 mL of ethyl ether/n-hexane mixture (0.6:99.4, v/v) was used for washing the SPE column, and 10 mL of the same solvent mixture (15:85, v/v) for desorbing cholesterol from the SPE column. Then the final extract was determined by GC-MS with electron impact ion source. The cholesterol was characterized according to retention time and characteristic fragments (m/z 213, 275, 301, 368, 386), and was quantitatively determined by external standard method in selected ion monitoring mode. The fragment of m/z 386 was selected as the target ion, and m/z 213 and m/z 275 were used as the reference ions. The average recovery was from 91.7% to 101%, and the relative standard deviations (RSDs) were below 6%, and the detection limit was 0.01 mg/L. A good linearity was obtained in the cholesterol concentration range of 0.24~6.0 mg/L with the correlation coefficient of 0.9996. The proposed method can be used to determine the cholesterol content in oil accurately, and the detection result can be one of the criteria judging the existence of drainage oil in edible oil.

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Simultaneous determination of seven compounds in Lonicera japonica by high performance liquid chromatography NIU Xiaoxue, CUI Xusheng, SU He, GUO Yuhai, DONG Xuehui* 2012, 30 (02):  211-214.  DOI: 10.3724/SP.J.1123.2011.10007 Abstract ( 1896 )   [Full Text(HTML)] () PDF (150KB) ( 424 )   A high performance liquid chromatographic (HPLC) method was developed to determine the contents of seven compounds in Lonicera japonica and Folium Lonicerae with maximum wavelength conversion program, and analyze the content differences between them. The separation was performed on an Agilent Eclipse Plus C18 column (250 mm×4.6 mm, 5 μm) operated at normal temperature with the gradient elution by two mobile phases of water (including 0.3% (v/v) formic acid) (A) and acetonitrile (B) at a flow rate of 1 mL/min. The maximum detection wavelength was set at 330 nm and 350 nm by conversion. The contents of chlorogenic acid and caffeic acid in Lonicera new leaves were 2.572% and 1.498‰ respectively, both higher than those cited in Chinese Pharmacopoeia, indicating that Lonicera new leaves have the necessity to be further studied and developed. This method is simple, rapid and highly sensitive. It is suitable for the simultaneous determination of the seven compounds and the quality control of Lonicera japonica

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Extraction of inosinic acid in Smoked Katsuwonus pelamis based on water WANG Tingting1*, CHEN Yihui2, HU Minjie1, LI Xuezhen2 2012, 30 (02):  215-218.  DOI: 10.3724/SP.J.1123.2011.10031 Abstract ( 3117 )   [Full Text(HTML)] () PDF (137KB) ( 367 )   A novel method for the extraction of inosinic acid in Smoked Katsuwonus pelamis based on water was developed. The inosinic acid was extracted by 95 ℃ water for 5 min. The subsequent analysis of inosinic acid was achieved on an Agilent Zorbax SB-C18 column (150 mm×4.6 mm, 5 μm) with the mobile phase of methanol-50 mmol/L ammonium acetate (5:95, v/v) at a flow rate of 1.0 mL/min at 30 ℃. The detection wavelength was set at 254 nm. The results showed that the linear range for inosinic acid in Smoked Katsuwonus pelamis was between 1.0 mg/L and 120.0 mg/L with the limit of detection (LOD, S/N=3) of 4 mg/kg and the limit of quantification (LOQ, S/N=10) of 12 mg/kg. At the spiked levels of 0.40, 2.00, 4.00 g/kg (n=3), the recoveries ranged from 84.6% to 100.2% with the relative standard deviations (RSDs) between 1.00% and 6.12%. Compared with traditional extraction method by perchloric acid, the extraction efficiency was improved by 37.0%. The novel method is safe, stable and accurate for the determination of inosinic acid in Smoked Katsuwonus pelamis, which can also be applied to the determination of inosinic acid in other foods and deserved to be spread.