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Chinese Journal of Chromatography
2007, Vol. 25, No. 2
Online: 30 March 2007

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“色谱固定相”专栏

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Development of Monolithic Materials and Their Applications in Microcolumn Separation Systems ZHU Guijie, ZHANG Lihua, LIANG Zhen, ZHANG Weibing, ZHANG Yukui 2007, 25 (2):  122-128.  Abstract ( 2166 )   [Full Text(HTML)] () PDF (5079KB) ( 808 )   Due to the good permeability, fast mass transfer property, high stability, and the ease of modification, monolithic materials have been widely used in microcolumn separation systems, not only as the stationary phase for CEC and capillary HPLC, but also as the matrix for sample concentration and enzyme reactor. This review summarizes the development of monolithic materials according to the papers published in the past two years.

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Applications of Molecularly Imprinted Column for Chiral Separation by High Performance Liquid Chromatography and Capillary Electrochromatography OU Junjie, DONG Jing, WU Minghuo, KONG Liang, ZOU Hanfa 2007, 25 (2):  129-134.  Abstract ( 2180 )   [Full Text(HTML)] () PDF (898KB) ( 1854 )   The molecularly imprinted polymer (MIP) monolithic column was firstly in situ polymerized in a traditional stainless-steel chromatographic column by using methylacrylic acid and S-Trger’s base as the functional monomer and rinted template molecules, respectively. The effects of the content of acetic acid and water in mobile phase on the separation were systematically investigated. The fast enantioseparation of the racemate on monolithic column was successfully realized by stepwise gradient elution. The MIP monolithic capillary column was also synthesized in a fused-silica capillary by in situ polymerization with 2-(dimethylamino)ethyl methacrylate (DAMA) as functional monomer. The enantioseparation of 1,1′-bi-2-naphthol (BNL) on the obtained MIP capillary column was achieved in capillary electrochromatography (CEC). The results indicated that other acidic template can be imprinted by using basic DAMA as functional monomer, which enlarge the application fields of imprinting molecules.

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Ligand Screening in Affinity Chromatography and Its Applications ZHAO Rui, LIU Guoquan 2007, 25 (2):  135-141.  Abstract ( 2186 )   [Full Text(HTML)] () PDF (2060KB) ( 835 )   Affinity chromatography is one of the most powerful techniques in selective purification and isolation of a great number of compounds. Affinity ligand is the most important factor in affinity chromatography, therefore, the selection and the screening of affinity ligand become the first issue to be considered when a novel type of affinity packing or a novel system of affinity chromatography needs to be developed. In combination with the research work of the author’s group, this paper briefly summaries the recent progresses in selection, screening and application of affinity ligands. A new screening method with antisense peptide based combinatorial peptide libraries has been developed to search the affinity ligands for target proteins and peptides. This strategy is simpler and more effective than the conventional combinatorial strategy. The work including syntheses and screening is greatly reduced and the structural determination of the ligands becomes easy by using this method. Furthermore, the new method has been successfully applied to the screening of inhibitors for influenza A virus and SARS coronavirus, as well as the construction of quartz crystal microbalance (QCM) biosensor for human interferon-β.

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Development of  Preparation and Application of Organic Polymer Monolithic Columns YIN Junfa, WEI Xiaoyi, YANG Gengliang 2007, 25 (2):  142-149.  Abstract ( 2307 )   [Full Text(HTML)] () PDF (215KB) ( 1371 )   In the past years, comprehensive attention was paid on monolithic materials for high performance liquid chromatography (HLPC) and capillary electrochromatogrphy (CEC), due to their superior porosity and hence good permeability, high surface area and high diffusion mass transfer. They are well suitedfor both small molecules and large biopolymers. Monolithic polymer based stationary phases are the continuous unitary porous structure prepared by in situ polymerization inside the column tubing and, if necessary, the surface can be functionalized with various functional groups. This review summarizes the progress in preparation and application of polymer monoliths, mainly according to the literatures published from 2003 to 2006.

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Applications of Monoliths in Sample Preconcentration WEI Fang, LIN Bo, FENG Yuqi 2007, 25 (2):  150-156.  Abstract ( 2371 )   [Full Text(HTML)] () PDF (199KB) ( 1044 )   This review focuses on the use of monoliths in sample preconcentration, with emphasis on the development and applications of monolith preconcentration coupled to high performance liquid chromatography, capillary electrophoresis, capillary electrochromatography, and on microfluidic chips as well. Novel modes of monolith preconcentration developed in recent years are also presented. Sixty-five references have been cited.

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Advances in Column and Stationary Phase of Capillary Electrochromatography GU Xue, QU Qishu, YAN Chao, 2007, 25 (2):  157-162.  Abstract ( 2511 )   [Full Text(HTML)] () PDF (167KB) ( 855 )   Capillary electrochromatography (CEC) has attracted increasing interests in recent years. It combines the advantages of high efficiency of capillary electrophoresis (CE) with high selectivity of high performance liquid chromatography (HPLC). CEC also has a double retention mechanism of both CE and HPLC and, therefore, is suitable for simultaneous separation and analysis of neutral and charged compounds. In this paper, the preparation methods for various types of capillary columns for electrochromatography are reviewed in detail and their advantages and disadvantages are discussed.

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Silica Based Stationary Phases for High PerformanceLiquid Chromatography JIANG Shengxiang, LIU Xia 2007, 25 (2):  163-173.  Abstract ( 1885 )   [Full Text(HTML)] () PDF (2372KB) ( 1164 )   Combining with the work done in our laboratory, the silica-based packing materials for high performance liquid chromatography with 157 references are reviewed.

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Study on Separation of Microcystins Using Polymethacrylate-Based Capillary Monolithic Column GU Congying, LIN Li, FANG Nenghu, JIA Jinping 2007, 25 (2):  174-178.  Abstract ( 1929 )   [Full Text(HTML)] () PDF (859KB) ( 766 )   Polymethacrylate-based monolithic column was prepared in 150 μm i.d. capillary column in situ using butylmethacrylate and ethylene dimethacrylate. The application of methacrylate monolithic column in capillary high performance liquid chromatography (μ-HPLC) for separation of microcystins (MCs) with ultraviolet (UV) detection has been studied. The properties of the monolithic column could be easily tailored by altering the preparation conditions. For the good reproducibility in preparation of monolithic column, this method could be used for the analysis of samples in practical. The effects of composition of mobile phase, pH value, concentration of the buffer, and the flow rate of the mobile phase on the separation of microcystins were investigated. The optimum separation for microcystins, MC-LR, MC-YR, and MC-RR, was achieved with a gradient elution of mobile phase A (0.01 mol/L phosphate buffer, pH 2.5) and mobile phosphate B (acetonitrile). The standard microcystins could be baseline-separated within 9 min. The limits of detection (LODs) (S/N=3) for three standard microcystins were in the range of 0.80-1.03 mg/L. The intra-day and inter-day precisions of the method were obtained with the values of relative standard deviation less than 1.0% and 2.0%, respectively. This method was successfully used to analyze bloom samples and laboratory-cultured samples of cyanobacteria after performing solid phase extraction (SPE) using C18 cartridges for preconcentration. The whole procedure provided low LODs for MCs, e.g. the LOD for MC-LR was found to be 420 ng/L. This family of microcystin is analyzed by μ-HPLC using methacrylate monolithic column for the first time. It is shown that this method is promising in the routine analysis of microcystins in water samples in practical.

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New Developments on Monolithic Stationary Phase for Ion Chromatography LI Jing, ZHU Yan 2007, 25 (2):  179-182.  Abstract ( 1885 )   [Full Text(HTML)] () PDF (106KB) ( 760 )   In recent years, interest has increased in using porous monolithic stationary phase media for high performance separations of inorganic and organic ions. The paper reviews the developments and the new trends of the monolithic stationary phase on ion chromatography, including the advantages and the classification of monoliths, as well as their applications for the separation and analysis of ionic molecules.

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Numerical Study on Sample Stacking in Capillary Electrophoresis CAO Jun, HONG Fangjun, CHENG Ping 2007, 25 (2):  183-188.  Abstract ( 2014 )   [Full Text(HTML)] () PDF (844KB) ( 837 )   Sample stacking in capillary electrophoresis is one of the effective techniques to concentrate sample species, thus improving the detection sensitivity. A 1-D mathematical model, including the electrical potential distribution equation, the buffer concentration equation, as well as the sample electromigration and diffusion equation, is developed through proper simplifications and assumptions to study the sample stacking process in capillary electrophoresis. These coupled governing equations are solved using finite element method (FEM). The variations of the buffer concentration and the electrical field strength distribution with time as well as the electrical potential distribution in capillary during sample stacking are obtained. The sample stacking and the sample diffusion after stacking as well as the separation process of sample cations and anions are presented. It is found that the best stacking effect occurs near the entrance where the species have not been separated well. With the development of time, the stacking effect deteriorates while the distance between the positively and negatively charged particles becomes larger, and the separation effect becomes better. The effect of buffer concentration ratio on sample stacking is also analyzed. It is found that the relationship between sample stacking effect and the buffer concentration ratio is not linear and the maximum stacking effect is achieved within less time and migration distance when the buffer concentration ratio is higher because of the stronger electrical field strength in sample plug region. It is anticipated that the numerical model developed in this paper is helpful for the design and optimization of sample stacking devices.

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Development and Application of Screening Method for Steroid Dihydrofolate Reductase Inhibitors by High Performance Capillary Electrophoresis JIA Rui, LI Na, ZHU Ruohua 2007, 25 (2):  189-192.  Abstract ( 2728 )   [Full Text(HTML)] () PDF (293KB) ( 906 )   A novel screening method for dihydrofolate reductase inhibitors (DHFRI) using high performance capillary electrophoresis (HPCE) was developed. The separation was performed in a fused silica capillary column using disodium tetraborate (50 mmol/L, pH 9.18) buffer solution with 0.002% Brij-35. The separation temperature was controlled at 25 ℃ and a voltage of 25 kV was applied. The detection wavelength was 280 nm. Five μL of various concentrations of inhibitor was added to the enzyme reaction system consisting of 25 μL of 50 mmol/L pH 6.0 potassium phosphate buffer, 10 μL of 0.025 mg/mL dihydrofolate (FH2), 10 μL of dihydrofolate reductase (DHFR) (0.25 unit) and 5 μL of 0.5 mg/mL NADPH in a 300-μL sample tube, then mixed for 1 min and incubated for 30 min at room temperature. The reaction mixture injections were performed by pressure at 3.45 kPa (0.5 psi) for 10 s. With the developed CE method the substrate and product were baseline resolved within 19 min. The time course of the reaction was studied to show excellent correlation. Quantitative analysis of DHFR inhibition was performed by determining its dynamic parameters. The difference of peak areas between FH2 and FH4 was used to calculate the inhibitory rate. Three inhibitors, amethopterin, trimethoprim and folic acid, were used in the enzyme reaction system to test this method and their IC50 values determined were close to the literature values. It was demonstrated that the developed method is suitable for screening DHFRIs.

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Determination of Amino Acids in Tea Samples by Capillary Electrophoresis with Partition Cell and Indirect Ultraviolet Detection FU Guoni, HE Youzhao, WANG Xiaokui, WANG Lei 2007, 25 (2):  193-196.  Abstract ( 2554 )   [Full Text(HTML)] () PDF (255KB) ( 894 )   An improved capillary electrophoretic (CE) separation and indirect ultraviolet (in-UV) detection system was proposed for the amino acid analysis in tea samples with a homemade partition cell and a background electrolyte (BGE) of p-aminobenzoic acid (PAB). PAB improved the separation efficiency and detection limits of the amino acids. The partition cell prevented PAB from chemical reaction at the electrode, reduced baseline noise and kept electric current inside the cell. The separation parameters of the amino acids, such as different BGEs, BGE concentration, buffer pH and electroosmotic flow (EOF) modifiers, were investigated. The CE separation was carried out with the running buffer solution of pH 11.2, 10 mmol/L PAB containing 0.014 mmol/L cetyltrimethylamonium bromide (CTAB), an applied voltage of -15 kV and a detection wavelength of 254 nm. Sixteen amino acids were separated within 14 min under the selected conditions. The linear ranges of the amino acids were 0.02-0.60 mmol/L except for theanine (0.02-3.80 mmol/L) and γ-aminobutyric acid (0.02-2.00 mmol/L). The recoveries were in the range from 83.0% to 106%. The relative standard deviations of peak area were less than 5% (n=5) and the detection limits were in the range of 1.7-4.5 μmol/L. The method is fast, convenient and sensitive, and has been applied to the determination of 11 amino acids in tea samples satisfactorily.

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Effect of Mobile Phase on the Mass Recovery of rhIFN-γ in Protein Folding Liquid Chromatography WU Dan, WANG Chaozhan, GENG Xindu 2007, 25 (2):  197-202.  Abstract ( 2202 )   [Full Text(HTML)] () PDF (568KB) ( 668 )   Protein refolding is a key process for the production of recombinant proteins from E. coli. One of the effective techniques for protein refolding is through liquid chromatography named as protein folding liquid chromatography (PFLC). Mobile phase composition is one of the most important factors affecting the efficiency of protein renaturation in PFLC. Optimization of mobile phase composition in PFLC for protein renaturation with simultaneous purification is thus much more important than that in usual liquid chromatography. This study presents an approach with regard to the increase of protein production through optimizing the mobile phase composition of PFLC. Recombinant human interferon-γ (rhIFN-γ) was purified with simultaneous renaturation by high performance hydrophobic interaction chromatography (HPHIC) using a stationary phase with an end group of PEG-200. Effects of mobile phase composition, gradient elution mode, and flow rate on the recoveries of mass and bioactivity of rhIFN-γ were investigated. It was found that these factors were very important for refolding with simultaneous purification of rhIFN-γ by PFLC. This study highlights the importance of optimizing the mobile phase composition in PFLC for increasing the recovery of protein. Taking 3.0 mol/L (NH4)2SO4 +0.05 mol/L KH2PO4 (pH 7.0) and 0.05 mol/L KH2PO4 (pH 7.0) as mobile phases A and B, respectively, the highest mass recovery was obtained under a nonlinear gradient elution for 35 min.

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Study on Enantioselectivity of Celluloses Derived by Phenylcarbamate at 2,3- or 2,3,6-Positions CHANG Yinxia, ZHOU Lingling, YUAN Liming 2007, 25 (2):  203-206.  Abstract ( 2107 )   [Full Text(HTML)] () PDF (247KB) ( 677 )   Cellulose-2,3,6-trisphenylcarbamate, cellulose-2,3-bisphenylcarbamate, cellulose-2，3，6-tris(3,5-dimethylphenylcarbamate) and cellulose-2,3-bis(3,5-dimethylphenylcarbamate) were synthesized and respectively coated on silica gel as chiral stationary phases for high performance liquid chromatography (HPLC). Nine pairs of enantiomers, which are (±)-phenyl-1,2-ethanediol, (±)-2-phenyl-1-propanol,  DL-alpha-methylbenzylamine, DL-mandelic acid, (±)-1-(1-naphthyl) ethanol,  (±)-propranolol, (±)-3-benzyloxy-1,2-propanediol,  DL-tyrosine and (±)-di-O,O-p-toluyl-D-tartaric acid, were separated using hexane-isopropanol as mobile phase on the columns packed with the chiral stationary phases. For comparative reasons, the ratio of hexane/isopropanol in the eluent was kept at 9∶1 (v/v) in all experiments, and the chromatographic separations were performed at 30 ℃ with a flow rate of 0.5 mL/min. All the test solutes were detected at 254 nm. The results showed that enantioseparation of cellulose-2,3-bisphenylcarbamate was better than cellulose-2，3，6-trisphenylcarbamate for the test enantiomers, and cellulose-2,3-bis(3,5-dimethylphenylcarbamate) had low retention factors and short analysis times for most enantiomers and good separation factors for some racemates compared to cellulose-2，3，6-tris(3,5-dimethylphenylcarbamate).

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Determination of Protocatechuic Acid in Rat Plasma by High Performance Liquid Chromatography HAN Ying, XIONG Zhili, YANG Chunjuan, LIU Man, LI Famei 2007, 25 (2):  207-210.  Abstract ( 2290 )   [Full Text(HTML)] () PDF (222KB) ( 697 )   A method was developed for the quantitative determination of protocatechuic acid in rat plasma by high performance liquid chromatography (HPLC). With added p-hydroxybenzoic acid as internal standard, the plasma samples were extracted with a solvent mixture of methanol and acetonitrile (1∶5, v/v). The analyte was determined by HPLC with a DiamondsilTM C18 column and a mobile phase of acetonitrile-water (adjusted to pH 2.5 with H3PO4 , 9∶91, v/v) at a flow rate of 1.2 mL/min. The UV detection wavelength was 260 nm. The assay exhibited a good linearity in the concentration range from 0.050 to 3.20 mg/L with a correlation coefficient of 0.9978. The limit of quantification was 0.050 mg/L. The relative standard deviations of  intra-day and inter-day determination  were both less than 7.0% and the accuracy ranged from -1.4% to 2.6%. The extraction recoveries of protocatechuic acid  from rat plasma samples at three concentration levels were 83.4%, 87.3%, and 91.1%, respectively. The developed method was applied to a pharmacokinetic study. The main pharmacokinetic parameters in rats after a single oral dose of 10 mL/kg body weight were as follows: Cmax of (3.16±0.03) μg/mL, tmax of (0.50±0.00) h, AUC0t of (39.9±5.9) μg·mL-1·h, AUC0∞ of (54.8±8.1) μg·mL-1·h and t1/2 of (3.87±0.25) h. The method was proved to be simple, sensitive and accurate, thus suitable for the pharmacokinetic study of protocatechuic acid in rat plasma.

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Determination of Serotonin in Rat Brain Microdialysate After i.p. Administration of Fluoxetine Hydrochloride byHigh Performance Liquid Chromatography GUO Yunzhen, YU Li, MA Zheng, GUO Xingjie 2007, 25 (2):  211-213.  Abstract ( 2193 )   [Full Text(HTML)] () PDF (240KB) ( 692 )   The concentration of serotonin (5-HT) in rat brain microdialysate before and after i.p. administration of fluoxetine hydrochloride was determined through precolumn derivatization by reversed-phase high performance liquid chromatography (RP-HPLC). A baseline separation of serotonin was achieved on a Hypersil C18 column (250 mm×2.0 mm, 5 μm) with acetonitrile-20 mmol/L sodium acetic solution (pH 5.0) (45∶55, v/v) containing 20 mmol/L of sodium octanesulfonate as the mobile phase. Fluorescence detection with the excitation wavelength at 330 nm and emission wavelength at 455 nm was used for serotonin. There was good linear relationship between the peak area and concentration in the range of 0.25-5.0 nmol/L(r=0.9991). The limit of quantitation was 0.25 nmol/L. The method is simple, accurate and can be applied to the determination of serotonin in biological specimen.

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Determination of Five 4-Hydroxycoumarin Rodenticides in Whole Blood by High Performance Liquid Chromatography with Fluorescence Detection JIN Micong, CHEN Xiaohong, LI Xiaoping 2007, 25 (2):  214-216.  Abstract ( 2184 )   [Full Text(HTML)] () PDF (226KB) ( 791 )   A simple, accurate and sensitive method has been developed for the simultaneous determination of warfarin, coumatetralyl, bromadiolone, flocoumafen and brodifacoum in whole blood by high performance liquid chromatography (HPLC) with fluorescence detection. The five 4-hydroxycoumarin rodenticides in whole blood were extracted by ethyl acetate, separated on XDB C18 column(150 mm×2.1 mm, 5 μm) by using the mobile phase consisting of methanol-0.2% acetic acid aqueous solution (88∶12, v/v) at a flow rate of 0.5 mL/min and detected with a variational time program for fluorescence wavelength. Each analyte was qualitatively determined with its fluorescence excitation spectrum, fluorescence emission spectrum and retention time being compared with those of the reference standard, and quantified with external calibration method. The linear range was 0.01-10.00 mg/L and the limit of quantification was 0.01 mg/L except warfarin of which the corresponding results were 0.05-10.00 mg/L and 0.05 mg/L. The recoveries were between 81% and 98% and the relative standard deviations (RSDs) were between 3.8% and 8.5%. This method can be used in the diagnosis of the clinical poisoned patients.

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Determination of Geniposidic Acid and Chlorogenic Acid in Male Flowers and Related Products of Eucommia ulmoides by Reversed-Phase High Performance Liquid Chromatography DONG Juane, MA Xihan 2007, 25 (2):  217-220.  Abstract ( 2440 )   [Full Text(HTML)] () PDF (228KB) ( 1016 )   A simple and rapid high performance liquid chromatographic method has been developed for the determination of geniposidic acid and chlorogenic acid in the male flowers and related products of Eucommia ulmoides. Two components were separated by a Shim-pack VP-ODS column (150 mm×4.6 mm, 5 μm) with a mobile phase of methanol-water-acetic acid (24∶75∶1, v/v) at a flow rate of 1 mL/min, column temperature of 30 ℃ and detection wavelength of 240 nm. Under the chromatographic conditions mentioned above, the method performance, such as the number of theoretical plate, resolution, trailing etc have all reached required level. The linear ranges were 0.025-0.400 g/L for geniposidic acid and 0.075-1.200 g/L for chlorogenic acid, with the correlation coefficients of 0.9997 and 0.9999, respectively. The average recoveries were 100.2% and 100.5%, and the relative standard deviations (RSDs) were 1.47% and 1.49% respectively. The minimum detection limits were 0.02 μg/L for geniposidic acid, and 0.06 μg/L for chlorogenic acid. The method developed has demonstrated the characteristics of simple mobile phase composition, short retention, good resolution, high repeatability and precision. It is suitable for the determination of the two compounds in the male flowers of E. ulmoides and related products.

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Determination of Polycyclic Aromatic Hydrocarbons in Soil by High Performance Liquid Chromatography with Fluorescence Detection QIAN Wei, NI Jinzhi, LUO Yongming, LI Xiuhua, ZOU Dexun 2007, 25 (2):  221-225.  Abstract ( 2520 )   [Full Text(HTML)] () PDF (254KB) ( 1534 )   Polycyclic aromatic hydrocarbons (PAHs) are the environmental organic pollutants which can induce cancers, teratogeny and organism saltation. Therefore, a reliable detection method is essential for studying the environmentally hazardous PAHs. The high performance liquid chromatography with a highly sensitive fluorescence detector was introduced to determine 15 PAHs of the priority pollutants named by the US Environmental Protection Agency (EPA) in soil. The gradient elution procedure was improved and the detection wavelength was optimized. The detection limits and the recoveries of the improved method for the 15 PAHs were in the ranges of 0.12 μg/kg to 1.57 μg/kg and 73% to 126%, respectively. The relative standard deviations of this method were in the range of 0.53% to 3.57%. The results indicated that this method is a reliable detection method with low detection limit, high sensitivity and repeatability for the determination of PAHs in soil.

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Simultaneous Determination of Captan and Folpet Pesticide Residues in Apples by Solid-Phase Extraction and High Performance Liquid Chromatography WANG Shuju, YU Yanbin, TAN Peigong, MIAO Zaijing, WEI Yishan 2007, 25 (2):  226-229.  Abstract ( 2501 )   [Full Text(HTML)] () PDF (214KB) ( 736 )   A method for the simultaneous determination of captan and folpet pesticide residues in apples was developed by solid-phase extraction and high performance liquid chromatography. The sample was extracted with acetonitrile and cleaned-up by a mixture of homemade sorbent and silica gel with hexane-dichloromethane-acetonitrile (50∶49∶1, v/v) as the eluent. The cleaned effects by using Florisil column, amino column, the mixed sorbent were compared, and the effect of the mixed sorbent was the best. The optimal analytical conditions were follow as: an methanol-acetonitrile-water (50∶5∶45, v/v) containing 0.1 mmol/L acetic-acetate buffer (pH 3.80) as the mobile phase, detection at 210 nm. The method had a good linear relationship in the range of 0.40-8.00 mg/kg for captan and folpet (r＞0.9999). The detection limits of captan and folpet were 0.27 mg/kg and 0.20 mg/kg, respectively. The relative standard deviations (RSDs) of retention time were no more than 0.60%. The average recoveries of captan and folpet from the apples spiked at three levels ranged from 69.3%-106% and 101%-108%, with RSD of 3.7%-4.7% and 1.3%-5.4%, respectively.

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Determination of Major Carbonyls in Mainstream Smoke by Rapid Column High Performance Liquid Chromatography HUANG Yun, WANG Yigeng, MIAO Mingming, ZHAO Qihua, YANG Guangyu 2007, 25 (2):  230-233.  Abstract ( 2225 )   [Full Text(HTML)] () PDF (231KB) ( 898 )   The determination of major carbonyl compounds in mainstream cigarette smoke by rapid column high performance liquid chromatography was investigated. The cigarette smoke was collected using a Cambridge filter treated with acidic solution of 2,4-dinitrophenylhydrazine. Formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, 2-butanone and butyraldehyde were extracted from the Cambridge filter with 50 mL of 2% pyridine acetonitrile solution. The carbonyl compounds in samples were separated on a ZORBAX Stable Bound rapid column (50 mm×4.6 mm, 1.8 μm) in approximately seven minutes and then determined by high performance liquid chromatography with a diode array detector. The average recoveries  were in the range of 89.1% to 99.2% and the relative standard deviations (RSDs) were generally below 6.0%. The eight carbonyl compounds in the mainstream smoke of five brands of cigarettes were determined using this method. This method is faster, simpler and consumes less solvent. It is suitable for rapid analysis of carbonyl compounds in mainstream cigarette smoke.

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Determination of Trace Estrogens in Cosmetic Water by Liquid-Phase Microextraction Coupled with High Performance Liquid Chromatography XIAO Xiaohua, YIN Yi, HU Yuling, LI Gongke 2007, 25 (2):  234-237.  Abstract ( 2176 )   [Full Text(HTML)] () PDF (367KB) ( 844 )   Liquid-phase microextraction (LPME) was introduced to establish a two-phase system in solvent microextraction with the integrated features of sampling, extraction, concentration and injection in a single step. It was proved that this process is a fast, effective and low-cost sample preparative method and widely used in biomedical, environmental and food analysis, as well as in other fields. In this study, a rapid method for the determination of trace estrogens (ethinyl estradiol, estradiol, estriol, and estrone) in cosmetic water by LPME coupled with high performance liquid chromatography (HPLC) was developed. The extraction conditions of LPME, such as extraction solvent, solvent volume, stirring speed, extraction time, pH value and salt concentration of the donor phase, were optimized. The enrichment factors of the estrogens was from 247 to 343. The linear detection ranges of the method were from 2 to 200 μg/L with  the detection limits from 0.4 to 1.0 μg/L. The recoveries ranged from 101.2% to 114.9% and the relative standard deviations were less than 7.5% for cosmetic water samples. The method is suitable for the determination of trace estrogenic compounds in cosmetic water samples.

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Determination of 12 Sulfonamides in Cosmetics by Ultra Performance Liquid Chromatography ZHENG Hehui, WANG Ping, LI Jie 2007, 25 (2):  238-240.  Abstract ( 2083 )   [Full Text(HTML)] () PDF (193KB) ( 964 )   A method for the determination of 12 sulfonamides (SAs) (sulfanilamide, sulfamonomethoxine, sulfacetamide, sulfamethoxazole, sulfadiazine, sulfisoxazole, sulfathiazole, sulfadimethoxine, sulfamerazine, sulfaquinoxaline, sulfamethazine, sulfanitran) in cosmetics was developed by ultra performance liquid chromatography with photodiode array detector (UPLC-PDA). The chromatographic column used was Acquity UPLCTM BEHC C18 (50 mm×2.1 mm, 1.7 μm) and the mobile phase was acetonitrile-0.1% formic acid aqueous solution. A gradient elution program was utilized for the separation and determination. After liquid-liquid extraction, SAs were separated and detected by UPLC-PDA. The qualification analysis was done by using retention time and spectrum, and the quantification was based on the detection wavelength of 268 nm. The limits of qualification (S/N=3) and quantification (S/N=10) for 12 SAs were 1 μg/g and 2-3 μg/g, respectively. The correlation coefficient of linear calibration curve was over 0.9997 within the SAs concentration range of 1-25 mg/L (except sulfanitran 0.5-12.5 mg/L). At the spiked levels of 40 and 8 μg(except sulfanitran 20 and 4 μg), the average recoveries for 12 SAs were 86.8%-98.1% and 80.1%-96.9%, respectively. Relative standard deviations were less than 10%. Routine tests show that the method is simple, fast, and has a good separation efficiency. It can be routinely used for the determination of these SAs in cosmetics.

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Determination of Standard Value of Sulfate Standard Solution by Ion Chromatography ZHANG Liping, XING Zhi, FENG Lu, LI Heng 2007, 25 (2):  241-244.  Abstract ( 2089 )   [Full Text(HTML)] () PDF (134KB) ( 758 )   A method for precise quantitation of sulfate in standard solutions by ion chromatography with suppression conductivity detection has been developed. The separation of sulfate was conducted on an IonPac AS19 anion exchange column (2 mm×250 mm) with NaOH solution as isocratic eluent. The injection volume was 25 μL. An orthogonally designed experiment was carried out to evaluate the effects of the experiment factors, such as column temperature, concentration of eluent NaOH, flow-rate of the eluent, and cell temperature. The optimal chromatographic conditions obtained were as follows: column temperature, 30 ℃; NaOH concentration,  30 mmol/L; flow-rate of the eluent, 0.25 mL/min; cell temperature, 35 ℃.The detection limit (3σ) was 0.005 mg/L. On the level of 4.5 mg/L sulfate, the relative standard deviation (RSD) was 0.44% (n=8). The linear range of calibration curve was 1.0-50.0 mg/L. The reliability of method was shown by the evaluation of stability of calibration curves. The variance analysis showed that the intercept and slope of 7 calibration curves were controlled statistically in the desired range. The reliability of method was shown by quality control samples, where RSD and relative error were less than 0.9%, and 0.8%, respectively. Average recovery of standard addition was 95.5%-105%. The method has been applied to the  quantitation of sulfate in standard solution.

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Determination of 1-Hydroxyethylidene-1,1-Diphosphonic Acid in Recycle-Cooling Water by Ion Chromatography MA Jian, YUAN Dongxing, GUAN Bin, YANG Rong, GE Laowei 2007, 25 (2):  245-247.  Abstract ( 2979 )   [Full Text(HTML)] () PDF (178KB) ( 822 )   1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) is usually used as a scale and corrosion inhibitor in recycle-cooling water for steel industry. The quick and accurate analysis of HEDP concentration in water is of importance to control the inhibitor adding program. However, the common method for HEDP analysis, which determines the total phosphate in water samples, may suffer the serious problem of incorrectly including degraded HEDP as the active HEDP reagent. In this study, the method of  the determination of HEDP in recycle-cooling water by ion chromatography was investigated. The chromatographic parameters, including elution and detection, were optimized. The separation was achieved on an IonPac AS14A column with NaOH solution of 80 mmol/L as the eluent at a flow rate of 1.0 mL/min, and the detection was performed by a suppressed conductivity detection mode with the injection volume of 25 μL. The method showed good linearity within the range of 0.25 and 25 mg/L with an average recovery of 102%. The detection limit of the method reached as low as 0.1 mg/L. The relative standard deviations for 0.25 and 0.5 mg/L HEDP standard solutions were 4.7% and 3.5% (n=13), respectively. The method has been applied for the determination of HEDP in recycle-cooling water samples with the advantages of being simple, fast, sensitive, and interference free.

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Quantitative Relationship Between Gas Chromatographic Retention Time and Structural Parameters of Alkylphenols RUAN Xiaofang, ZHANG Ruisheng, YAO Xiaojun, LIU Mancang, FAN Botao 2007, 25 (2):  248-253.  Abstract ( 2318 )   [Full Text(HTML)] () PDF (441KB) ( 595 )   Alkylphenols are a group of permanent pollutants in the environment and could adversely disturb the human endocrine system. It is therefore important to effectively separate and measure the alkylphenols. To guide the chromatographic analysis of these compounds in practice, the development of quantitative relationship between the molecular structure and the retention time of alkylphenols becomes necessary. In this study, topological, constitutional, geometrical, electrostatic and quantum-chemical descriptors of 44 alkylphenols were calculated using a software, CODESSA, and these descriptors were pre-selected using the heuristic method. As a result, three-descriptor linear model (LM) was developed to describe the relationship between the molecular structure and the retention time of alkylphenols. Meanwhile, the non-linear regression model was also developed based on support vector machine (SVM) using the same three descriptors. The correlation coefficient (R2) for the LM and SVM was 0.98 and 0.92, and the corresponding root-mean-square error was 0.99 and 2.77, respectively. By comparing the stability and prediction ability of the two models, it was found that the linear model was a better method for describing the quantitative relationship between the retention time of alkylphenols and the molecular structure. The results obtained suggested that the linear model could be applied for the chromatographic analysis of alkylphenols with known molecular structural parameters.

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Determination of Underivatized  Long-Chain Fatty Acids in Edible Oils by Fast Gas Chromatography MENG Zhe, WEN Dawei, LIAO Yiping, LIU Huwei 2007, 25 (2):  254-257.  Abstract ( 2207 )   [Full Text(HTML)] () PDF (304KB) ( 844 )   A fast gas chromatography (GC) method with short micro-bore capillary column was developed for the determination of underivatized long-chain fatty acids (LCFAs) in edible oils. Baseline separation of eight kinds of LCFAs (dodecanoic acid, tetradecanoic acid, palmitic acid, oleic acid, stearic acid, eicosanic acid, erudcic acid, behenic acid) was achieved within 2 min with high resolution performance. The linear correlation coefficients for underivatized LCFAs were higher than 0.988 and detection limits (at signal-to-noise of 3∶1) were 2.80-9.60 mg/L. The method is easy and low-cost and has the ability to achieve an accurate determination of the LCFAs in three edible oils.

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Direct Determination of Four Components in Compound Paracetamol and Diphenhydramine Tablets by Wide Bore Capillary Gas Chromatography YAO Ruxin, XU Qingqin, DU Liming 2007, 25 (2):  258-261.  Abstract ( 2487 )   [Full Text(HTML)] () PDF (267KB) ( 722 )   A gas chromatographic method for the simultaneous determination of paracetamol (PAR), caffeine (CAF), diphenhydramine hydrochloride (DPH) and ephedrine hydrochloride (EPD) in Compound Paracetamol and Diphenhydramine Tablets has been developed. The separation of several components was achieved on a wide bore capillary column HP-1 (10 m×0.53 mm, 2.65 μm) with flame ionization detector (FID), and with pentadecane as internal standard, at a column temperature of 190 ℃. The linear ranges of detection for PAR, CAF, DPH and EPD were found to be 50-2400, 10-500, 10-500 and 10-500 mg/L, respectively. The detection limits were 1-30 μg/L, the average recoveries were 98.5%-101.1%. For intra-day assay, the relative standard deviations were less than 2.2%. The method has been applied successfully to the determination of fourfold mixture of PAR, CAF, DPH and EPD in pharmaceutical preparations. The developed method is rapid and sensitive and therefore provides a scientific basis for the quality control of Compound Paracetamol and Diphenhydramine Tablets.

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Determination of Five Polybrominated Diphenyl Ether Residues in Deep-Sea Fish Oil Using Gas Chromatography-Negative Chemical Ionization/Mass Spectrometry LIN Zhuguang, TU Fengzhang, MA Yu, CHEN Meiyu, ZHANG Lili, SUN Ruonan, ZOU Ximei, LI Xiaobo, CHEN Zhaobin 2007, 25 (2):  262-266.  Abstract ( 2343 )   [Full Text(HTML)] () PDF (355KB) ( 893 )   Polybrominated diphenyl ethers (PBDEs) are a kind of brominated flame retardants (BFRs), which refer to compounds used in some plastics to impede or even suppress the combustion process. As the emission or disposal of plastics, PBDE residues have been found in both environment and biota. In this work, an analytical method was developed for the simultaneous determination of 5 PBDE residues in deep-sea fish oil. PBDEs were extracted from deep-sea fish oil with n-hexane, cleaned up on a silical gel column, and determined by using gas chromatography-negative chemical ionization/mass spectrometry (GC-NCI/MS) in the selected ion-monitoring (SIM) mode, with PCB103 as the internal standard. Meanwhile, the characteristic ion and fragmentation mechanism of some PBDEs in NCI/MS were evaluated. Recovery studies were performed at 20.0 and 100.0 μg/kg fortification levels for each PBDE, and the recoveries ranged from 88.6% to 111.3% with relative standard deviations between 3.8% and 13.5% for different PBDEs. The limits of detection (LOD) were from 0.77 to 1.34 μg/kg for different PBDEs. The developed method was linear over the range assayed, 1.0-500.0 μg/kg, with correlation coefficients larger than 0.9992. The developed method has also been successfully applied to the determination of PBDEs in several deep-sea fish oil samples and the three most abundant PBDEs (PBDE-47, PBDE-99 and PBDE-100) were found.

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Analysis of Volatile Compounds in Bighead Carp by Microwave Distillation and Solid Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry and Olfactometry ZHAO Qingxi, XUE Changhu, XU Jie, SHENG Wenjing, XUE Yong, LI Zhaojie 2007, 25 (2):  267-271.  Abstract ( 2698 )   [Full Text(HTML)] () PDF (328KB) ( 1189 )   A technique for the analysis of flavour compounds from fish muscle employing microwave distillation (MD), solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and olfactometry is described, and 53 compounds responsible for the aroma of bighead carp were identified from NIST 02 MS data base. The extraction of microwave distillation was developed by optimizing the flow rate of carrier gas, heating time and power. Solid phase microextraction procedure was optimized by using different kinds of fiber for the qualitative determination of the volatile compounds observed in the headspace of microwave distillation, including extraction time, temperature, magnetic stirring speed and desorption time in GC-MS equipment. Furthermore, a simple data acquisition and processing system was developed by using human nose as a sensitive detector for the identification of flavour and off-flavour key compounds in fish tissue. The result showed that the components associated with fish flavour were mostly 6-9 carbon aldehydes, ketones and alcohols. According to the olfactory analysis, these compounds were characterized by grassy, fishy, earthy or muddy odors separately, and their synergistic actions were forming the distinct fishy and earthy odors of bighead carp. The rapid method developed by this study may be applied to quantitative analysis of the off-flavour compounds in fresh-water fish.

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Simultaneous Determination of Phthalates and Parabens in Cosmetic Products by Gas Chromatography/Mass Spectrometry Coupled with Solid Phase Extraction SHEN Haoyu, YING Liyan, CAO Yunfeng, PAN Gang, ZHOU Lu 2007, 25 (2):  272-275.  Abstract ( 3102 )   [Full Text(HTML)] () PDF (1563KB) ( 1461 )   Studies have been carried out on the simultaneous determination of 8 phthalates, i.e. di-ethyl phthalate (DEP), di-propyl phthalate (DPP), di-isobutyl phthalate (DIBP), di-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-cyclohexyl phthalate (DCHP), di-(2-ethylhexyl) phthalate (DEHP), di-octyl phthalate (DOP) and 4 parabens, i.e. methylparaben (MPB), ethylparaben (EPB), propyl paraben (PPB), and butyl paraben (BPB) by gas chromatography in combination with mass spectrometry (GC/MS) in electron ionisation mode (EI) with selected-ion monitoring (SIM) acquisition method. The phthalates and parabens in 15 cosmetic products, including hair sprays, perfumes, deodorants, cream, lotion, etc. were determined. The determination of the samples were performed after sonication-assisted extraction with methanol, cleaned up with an LC-C18 column (3 mL) and analyzed by GC/MS method. The base peak (m/z 149) of the phthalates and the base peak (m/z 121) of the parabens were selected for the screening studies. The characteristic ions, m/z 121, 149, 177, 222 for DEP; m/z 149, 191, 209 for DPP; m/z 57, 149, 223 for DIBP; m/z 104, 149 for DBP; m/z 91, 132, 149, 206 for BBP; m/z 55, 149, 167 for DCHP; m/z 113, 149, 167, 279 for DEHP; m/z 149, 279 for DOP; m/z 65, 93, 121, 152 for MPB; m/z 93, 121, 138, 166 for EPB; m/z 93, 121, 138, 180 for PPB; and m/z 93, 121, 138, 194 for BPB were chosen for quantitative studies. These techniques are capable to detect phthalates and parabens at the level of 0.1-5.0 μg/kg. Overall recoveries were 80%-100% with relative standard deviations (RSDs) less than 10%. Only one of the 15 examined samples was free from phthalates and parabens. The rest 14 samples were found to contain at least 3 or more of these phthalates and/or parabens. The predominant phthalates detected in the studied samples were MPB, PPB, DPP, DCHP and DEHP. The residue levels were at 1.42-4278 mg/kg.

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Determination of Perfluorooctanoic Acid and Its Salts in the Coating Layer of Nonstick Pan by Gas Chromatography/Mass Spectrometry Coupled with Accelerated Solvent Extractor BAI Hua, HAO Nan, CUI Yanni, ZHOU Xin, CAI Tianpei, ZHANG Qing, WANG Chao, WANG Junbing 2007, 25 (2):  276-279.  Abstract ( 2351 )   [Full Text(HTML)] () PDF (301KB) ( 883 )   A sensitive, accurate and reproducible analytical method was developed and validated to quantify perfluorooctanoic acid (PFOA) and its salts  in the coating layer of nonstick pan. Scraped samples of 0.5 gram were directly extracted with acetonitrile using an accelerated solvent extractor at 175 ℃, 10.3 MPa for 20 min. After rotary evaporation concentration, the PFOA was derivatized with acetyl chloride and methanol at 65 ℃ for 60 min in an air-tight container. An HP-1 MS capillary column (30 m×0.25 mm, 0.33 μm) was used for the separation of the analyte. The procedure for the analysis of PFOA was based on gas chromatography interfaced to negative chemical ion mass spectrometry, operated in selected ion monitoring mode. Selected ions of m/z 312, 350, 378, 408, 428 were chosen for quantitation. The assay was linear over the range of 0-1000 μg/L, and the detection limit of PFOA was 5 μg/kg. The precision and recovery were assessed on four different concentrations (5, 20, 100, 500 μg/kg). The recoveries were in the range of 90.9%-96.2% and the relative standard deviations were 1.37%-6.37%. The procedure was applied to monitoring PFOA in the coating layer of nonstick pan from supermarket and no positive result was found.