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Chinese Journal of Chromatography
2009, Vol. 27, No. 3
Online: 30 May 2009

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A novel protein equalizer based on single chain variable fragment display M13 phage library for nephropathy patient urine study ZHAO Peng, TAO Dingyin, LIANG Zhen, ZHANG Lihua, ZHANG Yukui 2009, 27 (3):  249-253.  Abstract ( 2444 )   [Full Text(HTML)] () PDF (1325KB) ( 838 )   A novel protein equalizer was developed with single chain variable fragment (scFv) library displaying M13 phage covalently bonded on monolithic cryogel. Due to the great number and various kinds of displayed scFv fragments, as well as strong and specific binding capacity between scFv fragments and proteins, a new protein equalizer technology is preferable in the pretreatment of complex protein samples. After the sample dissolved in phosphate buffer solution (PBS), it was repeatedly loaded onto the equalizer for five times, the bound proteins were in sequence eluted by 2 mol/L NaCl and 50 mmol/L Gly-HCl (pH 2.5) solution, followed by digestion with thrombin. All proteins or peptides collected from each fraction were further analyzed by high performance liquid chromatography-electrospray tandem mass spectrometry (RPLC-ESI-MS/MS) with a serially coupled long microcolumn. Compared with the untreated samples, the identified protein number was increased from 142 to 396. Furthermore, from sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis results, it was found that the protein concentration difference was reduced obviously in the eluant of direct sample loading, and most high abundance proteins were identified in the eluant of NaCl. All these results demonstrate that the novel protein equalizer with scFv display M13 phage library immobilized on cyrogel could effectively reduce the dynamic range of proteins in complex samples, enabling the identification of more low abundance proteins.

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Simultaneous determination of 128 pesticide residues in milk by liquid chromatography-tandem electrospray mass spectrometry ZHENG Junhong, PANG Guofang, FAN Chunlin, WANG Minglin 2009, 27 (3):  254-263.  Abstract ( 2560 )   [Full Text(HTML)] () PDF (415KB) ( 1183 )   A method has been developed for the simultaneous determination of 128 pesticide residues in milk by liquid chromatography-tandem electrospray mass spectrometry (LC-ESI-MS/MS). A total of 10 mL milk was extracted with 20 mL acetonitrile (plus 4 g magnesium sulfate and 1 g NaCl) for two times. The concentrated supernatant was cleaned-up by a C18 solid phase extraction cartridge to remove the lipophilic compounds. The eluate was concentrated to about 0.5 mL in 45 ℃ water bath with nitrogen. The 1 mL mixture of acetonitrile and water (3:2, v/v) was added into the sample and mixed thoroughly for 30 s. The sample solution was filtered by 0.2 μm millipore filters before LC-ESI-MS/MS determination. This method was evaluated at the two spiked levels of 2 times and 8 times of limits of the detection (LODs) in 5 parallel experiments, respectively. The results showed that the average spiked recoveries of 128 pesticides at the low spiked level (0.14 μg/L~0.62 mg/L) were from 60.4% to 118.4% with relative standard deviations (RSDs) of 2.1%~24.3%, and the average spiked recoveries at the high spiked level (0.56 μg/L~2.48 mg/L) were from 64.4% to 118.5% with the RSDs of 1.3%~24.1%. The method showed a good linear relationship with the correlation coefficients over 0.99. The LODs were from 0.07 μg/L to 0.31 mg/L. This method is selective, accurate and easy to operate.

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Analysis of minor curcuminoids in Curcuma longa L. by high performance liquid chromatography-tandem mass spectrometry LI Wei, XIAO Hongbin, WANG Longxing, LIANG Xinmiao, 2009, 27 (3):  264-269.  Abstract ( 2621 )   [Full Text(HTML)] () PDF (952KB) ( 993 )   A high performance liquid chromatography-tandem mass spectrometric method has been developed for the simultaneous analysis of three minor curcuminoids in the crude extract of Curcuma longa L. After ultrasonic extraction with ethanol, the sample was separated on a Microsorb C18 column (250 mm×4.6 mm, 5 μm) with the gradient elution of acetonitrile and 0.1% (v/v) formic acid aqueous solution as mobile phase, then detected by electrospray ionization tandem mass spectrometry in multi-reaction monitoring (MRM) mode. On the basis of analysis of the fragmentation patterns, the identification of the minor ones was achieved in a single experiment using MRM with 8 precursor-product ion transitions for each component. Using this technique, the three minor curcuminoids were observed in C. longa L. for first time and the limit of detection was 0.2 μg/L. The experimental results show that this method is simple, rapid, accurate, sensitive and suitable for the analysis of curcuminoids in the complex samples of traditional Chinese medicine.

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Analysis of the effects of 17β-oestradiol and serum deprivation on the contents of proteins in breast cancer cells by isobaric tags for relative and absolute quantification and two-dimensional liquid chromatography-tandem mass spectrometry ZHU Lei, NI Guoxin, ZHANG Zhengxi, XU Xuemin, HU Xiaofang, LI Wei 2009, 27 (3):  270-278.  Abstract ( 2673 )   [Full Text(HTML)] () PDF (592KB) ( 805 )   Estrogen, hormones and growth factors in serum play important roles in the carcinogenesis and development of breast cancer. The study of the effects of the above factors on protein components and their contents in breast cancer cells is necessary for understanding the molecular mechanisms. In this study, isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) was employed to compare the differential protein expressions in MCF7 cells upon 17β-oestradiol (E2) stimulation or serum deprivation (SD) versus in normal conditions. A total of 576 proteins with the confidential level of ≥95% were identified, 26 proteins among the 576 proteins were found to be differentially expressed after E2 stimulation or serum deprivation, and among them 10 proteins were up-regulated and 16 proteins were down-regulated by more than two folds. Interestingly, both E2 and serum significantly altered the level of proteins involved in protein synthesis. This demonstrated iTRAQ coupled LC-MS/MS is an efficient methodology in comparative proteomics.

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Determination of fatty alcohol polyoxyethylene ether sodium sulphate by liquid chromatography-electrospray ionization mass spectrometry HUANG Xiaolan, WU Huiqin, HUANG Fang, LIN Xiaoshan, ZHU Zhixin 2009, 27 (3):  279-282.  Abstract ( 2740 )   [Full Text(HTML)] () PDF (501KB) ( 977 )   A method for the analysis of fatty alcohol polyoxyethylene ether sodium sulphate (AES) by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS) was established. The alkyl carbon number distribution, ethylene oxide number and average relative molecular mass in AES were determined by negative ion mode ESI/MS. Nitrogen nebulizer gas temperature was 325 ℃, nitrogen drying gas flow rate was 5.00 L/min, the mass scan range was from m/z 100 to 1000. The free sodium dodecyl sulfate (SDS) in AES was separated on a Zorbax SB-C18 column (150 mm×2.1 mm, 3.5 μm) with methanol-water (70:30, v/v) as the mobile phase at a flow rate of 0.3 mL/min, and then determined at m/z 265 by LC-MS with ESI in negative ion mode. The method has been applied for the determination of the AES samples, and the average ethylene oxide number was verified by nuclear magnetic resonance spectrum.

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Determination of N-nitrosodiethanolamine in cosmetics by isotope dilution-liquid chromatography- tandem mass spectrometry MA Qiang, WANG Chao, BAI Hua, WANG Xing, DONG Yiyang, WU Ting, ZHANG Qing, WANG Junbing, TANG Yingzhang 2009, 27 (3):  283-287.  Abstract ( 2748 )   [Full Text(HTML)] () PDF (313KB) ( 821 )   A comprehensive analytical method based on isotope dilution-liquid chromatography-tandem mass spectrometry has been developed for the determination of N-nitrosodiethanolamine in cosmetics. Water-soluble cosmetic samples were extracted with water. The extract was centrifuged, then the upper solution was cleaned up by an Oasis HLB solid phase extraction cartridge. Oil-soluble cosmetic samples were extracted by liquid-liquid partition with dichloromethane and water. Qualitative and quantitative analyses were carried out for the analyte under the multiple reaction monitoring (MRM) mode after the chromatographic separation on a Waters Atlantis T3 column (150 mm×2.1 mm, 3 μm ). The quantitation was performed with deuterated N-nitrosodiethanolamine as internal standard. The limit of quantitation (LOQ) for N-nitrosodiethanolamine was 50 μg/kg. The mean recoveries were 89.1%~98.2% at the spiked levels of 50~250 μg/kg, with the intra-day precision less than 9% and the inter-day precision less than 11%. The method is suitable for the determination of NDELA in cosmetics.

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Determination of 29 acidic herbicide residues in tea by gas chromatography-mass spectrometry YAN Hongfei, HUANG Zhiqiang, ZHANG Ying, LI Yongjun, WANG Meiling 2009, 27 (3):  288-293.  Abstract ( 2795 )   [Full Text(HTML)] () PDF (288KB) ( 941 )   A method was developed for the determination of 29 herbicide residues in tea. The target analytes were extracted with acetonitrile. The extract was cleaned up with an ENVI-Carb solid phase extraction column and derivatized with trimethylsilydiazmethan, then cleaned up through a Florisil solid phase extraction column. The derivatives were determined by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) mode. The separation and quantification were achieved using an HP-5MS silica capillary column (30 m×0.25 mm×0.25 μm) with a column temperature gradient from 50 ℃ (held for 1 min) to 160 ℃ at a rate of 4 ℃/min, held for 3 min and then increased to 300 ℃ for 5 min at a rate of 10 ℃/min. The average recoveries of these herbicides at three spiked levels (0.01, 0.05 and 0.1 mg/kg) ranged from 57.1% to 120.4% with the relative standard deviations (RSDs) ranged from 4.3% to 20.9%. The detection limits were from 0.002 mg/kg to 0.005 mg/kg. The method is easy, fast, and more sensitive. It also indicated that this method can meet the requirements for simultaneous determination of 29 herbicides in tea.

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Determination of hormone multi-residues in animal tissues by gas chromatography-mass spectrometry LIN Weixuan, DONG Weifeng, CHEN Xi, TIAN Miao, YU Ling, ZHAO Jinghong, YANG Chunguang 2009, 27 (3):  294-298.  Abstract ( 2619 )   [Full Text(HTML)] () PDF (392KB) ( 958 )   A method of gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of nine sex hormone residues, such as hexestrol, diethylstilbestrol, dienestrol, etiocholan-3α-ol-17-one, epitestosterone, estrone, estradiol, ethinylestradiol and estriol, in animal tissues was developed. The sex hormones were extracted with acetonitrile, then cleaned-up with a C18 solid-phase extraction (SPE) column. The microwave-assisted derivatization of the target components with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and trimethylchlorosilane (TMCS) (99:1, v/v) using pyridine as solvent was performed, and then the derivatives were analyzed by GC-MS. The limits of detection were 0.1~1 μg/kg for all hormones, and the limits of quantification were 0.2~2 μg/kg. The average recoveries of sex hormones were 68.8%~93.1%. The relative standard deviations (RSDs) of inter- and intra-assay were 4.1%~22.3% and 3.1%~17.9%, respectively. The real sample tests showed this method can be used for the sensitive and accurate determination of multi-sex hormones residues in biological samples.

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Scale-up of conical column with 10° opening angle as preparative liquid chromatographic column LU Liejuan, CHEN Jie, GUAN Yafeng 2009, 27 (3):  299-302.  Abstract ( 2602 )   [Full Text(HTML)] () PDF (5121KB) ( 692 )   A preparative scale liquid chromatographic column with the conical shape of 10° opening angle was constructed and evaluated. The column was designed with the inlet/outlet diameters of 54/27 mm, the column length of 150 mm and the column volume of 200 mL, and packed with the spherical C18 bonded silica with the particle size of 40~75 μm and the aperture of 11 nm. The mobile phase in the conical column showed a plug like flow profile and plug like chromatographic band shape. For naphthalene, the reduced plate height was about 2.11; the maximum sample load was 2.1 mg or 1.7 mL (10% reduction of plate number), which is 20%, 16% and 19% higher than that of cylindrical one of the same length and volume. As the injection mass increased from 2.4 mg up to 12 mg, the resolution of ethyl paraben/butyl (Rs2) reduced from 2.14 down to 1.71, and the butyl paraben/naphthalene (Rs3) from 2.91 down to 2.52; the injection volume increased from 3 mL up to 19 mL, Rs2 reduced from 2.23 down to 1.28, and Rs3 from 2.95 down to 2.30, while the peaks were still in symmetric shape without tailing. This characteristic of the column shall benefit for the separation of trace components from matrix. This demonstrated the conical shaped preparative columns would have a broad practical applicability for obtaining pure compounds.

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Comparison of pretreatment methods for the simultaneous deter-mination of diclazuril and toltrazuril residues in chicken tissues SHI Zuhao, GE Qinglian, LU Junxian, LIU Xuexian, GONG Jiansen, ZHU Liangqiang, QI Kezong, CHEN Dingding, PENG Kaisong 2009, 27 (3):  303-307.  Abstract ( 3250 )   [Full Text(HTML)] () PDF (320KB) ( 820 )   The effects of four pretreatment methods (acetonitrile extraction-evaporation concentration, acetonitrile extraction-solid phase extraction (SPE), matrix solid-phase dispersion (MSPD) extraction and MSPD-SPE) for the simultaneous analysis of diclazuril and toltrazuril residues in chicken tissues were compared. The average recovery of 70% for the former three methods as achieved. In comparison with other methods, the MSPD method saved more than 60% in time and solvent. So, MSPD as the sample pretreatment method, an MSPD-high performance liquid chromatography with ultraviolet detection (MSPD-HPLC/UV) method was established for the analysis. Under the optimal chromatographic conditions, the linear range was between 50 and 1000 μg/kg. At the added levels of 50, 500, 1000 ng/g, the recoveries of diclazuril and toltrazuril in chicken tissues ranged from 71.13%~84.02% with the relative standard deviations (RSD) in the range of 3.76%~12.11%, and the RSDs of intra- and inter-day analyses ranged from 3.70%~6.77%. The detection limits of diclazuril and toltrazuril were less than 10 μg/kg. The quantitative limits of diclazuril and toltrazuril were less than 20 μg/kg. The method meet the requirements of the residue analysis on accuracy and precision.

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Determination of carbendazim residue in orange and soil using high performance liquid chromatography SHEN Jing, LIU Jun, LIU Jian 2009, 27 (3):  308-312.  Abstract ( 2533 )   [Full Text(HTML)] () PDF (482KB) ( 767 )   An analytical method of high performance liquid chromatography (HPLC) was established for determining carbendazim residue in orange and soil. The residue was extracted with alkaline acetonitrile, cleaned-up by NH2 solid-phase extraction (SPE), separated on a Luna C18 column (250 mm×4.6 mm, 5 μm) using 10 mmol/L ammonium acetate solution (A) and acetonitrile (B) as the mobile phases with the gradient elution (0→15 min, 20%B; 15→25 min, 80%B; 25→35 min, 20%B) at a flow rate of 1.0 mL/min, and detected at 275 nm. The method showed a linear relationship between peak area and concentration at the range of 0.02~5.0 mg/L for carbendazim. The average recoveries of the method ranged from 89.2% to 102% with the relative standard deviations of 1.8%~ 9.1% at spiked level of 0.05~ 0.5 mg/kg. The limit of detection was 0.05 mg/kg in sarcocarp and soil, and that was 0.1 mg/kg in pericarp and whole orange. The method is characterized by simplicity, higher sensitivity and accuracy.

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Selection of mobile phases for the determination of γ-schisandrin and multi-active constituents in Schisandra chinensis and its preparations by high performance liquid chromatography YANG Xiaorong, XIANG Qingxiang, CHEN Jiaxuan 2009, 27 (3):  313-317.  Abstract ( 2454 )   [Full Text(HTML)] () PDF (422KB) ( 719 )   The systems of mobile phase for the determination of γ-schisandrin in Schisandra chinensis and its preparations were developed by high performance liquid chromatography (HPLC). The separation was performed on a Shim-pack VP-ODS column (250 mm×4.6 mm, 5 μm) at 30 ℃, the detection wavelength was set at 285 nm and the flow rate was 1.0 mL/min. Retention times and separation were investigated in mixed solution of three reference substances (γ-schisandrin, anwulignan, and deoxyschizandrin) and methanol extract of Schisandra chinensis by different systems and proportions of mobile phases to select optimal conditions for the determination of γ-schisandrin. The results showed that the complete separation of γ-schisandrin and anwulignan was difficult in the systems of methanol-water and methanol-acetic acid-water. The separation of γ-schisandrin, anwulignan and deoxyschizandrin can be completed in the systems of acetonitrile-methanol-water and acetonitrile-acetic acid-water when their proportions were suitable. The mobile phase of acetonitrile-methanol-water (17:58:25, v/v/v) was selected for the determination of deoxyschizandrin, γ-schisandrin and anwulignan in Schisandra chinensis and Hugan tablets. The determination results of the three substances were satisfactory with the relative standard deviations (n4) ranged from 0.95% to 5.8%, and the average recoveries ranged from 94.50% to 105.6%. The efficiency of separation and the results of determination were satisfactory for the real samples.

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Identification of the authentic quality of Longdanxiegan pill by systematic quantified fingerprint method based on three wavelength fusion chromatogram SUN Guoxiang, ZHANG Jingxian 2009, 27 (3):  318-322.  Abstract ( 2618 )   [Full Text(HTML)] () PDF (320KB) ( 766 )   The three wavelength fusion high performance liquid chromatographic fingerprints (TWFFP) of Longdanxiegan pill (LDXGP) was established to identify the quality of LDXGP by the systematic quantified fingerprint method. The chromatographic fingerprints (CFPs) of the 12 batches of LDXGP were determined by reversed-phase high performance liquid chromatography. The technique of multi-wavelength fusion fingerprint was applied during processing the fingerprints. The TWFFPs containing 63 co-possessing peaks were obtained when choosing baicalin peak as the referential peak. The 12 batches of LDXGP were identified with hierarchical clustering analysis by using macro qualitative similarity (Sm) as the variable. According to the results of classification, the referential fingerprint (RFP) was synthesized from 10 batches of LDXGP. Taking the RFP for the qualified model, all the 12 batches of LDXGP were evaluated by the systematic quantified fingerprint method. Among the 12 batches of LDXGP, 9 batches were completely qualified, the contents of 1 batch were obviously higher while the chemical constituents quantity and distributed proportion in 2 batches were not qualified. The systematic quantified fingerprint method based on the technique of multi-wavelength fusion fingerprint can effectively identify the authentic quality of traditional Chinese medicine.

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Influence factors of the separation of steroids using oil-in-water microemulsion liquid chromatography LI Ning, HOU Xuanzhu, YANG Wen, HUANG Guangliang, YE Xiujin 2009, 27 (3):  323-327.  Abstract ( 2479 )   [Full Text(HTML)] () PDF (500KB) ( 755 )   The effect of the varying operating parameters on the separation of steroids was studied by oil-in-water microemulsion liquid chromatography (MELC). The parameters included the surfactant concentration, the type of oil phase, the nature of organic solvent additives, and the pore size of the stationary-phase. The optimized conditions for the separation of 6 steroids were as follows: a Venusil ASB C18(T) column (5 μm, 30 nm, 250 mm×4.6 mm) was used at 35 ℃, the microemulsion mobile phase consisted of 30 g/L sodium dodecylsulfate (SDS), 0.8%(w/w) n-octane, 6.6%(w/w) n-butanol. The optimized method can be used for the separation, identification and simultaneous determination of steroids in bulk drugs and in pharmaceutical dose forms.

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Simultaneous determination of seven sexual hormones in essential oil by high performance liquid chromatography with diode array and fluorescence detectors WANG Xiaofang, ZENG Wenfang, WANG Jing, REN Ren 2009, 27 (3):  328-332.  Abstract ( 2466 )   [Full Text(HTML)] () PDF (406KB) ( 789 )   An efficient method for analyzing seven sexual hormones (estradiol-17β, estriol, estrone, testosterone, methyl-testosterone, progesterone and diethylstilbestrol) in essential oil by high performance liquid chromatography was developed. The samples were dissolved in n-hexane, then extracted with 90% methanol solution. The n-hexane layer was discarded and the methanol layer was cleaned-up twice with n-hexane. The target compounds were separated on an XTerraRP18 column (250 mm×4.6 mm, 5 μm) using water-methanol-acetonitrile (50:30:20, v/v/v) as mobile phase in isocratic mode, and detected by a diode array detector (DAD) and a fluorescence detector (FLD). The flow rate was 1.0 mL/min. Estriol, estradiol-17β, estrone, diethylstilbestrol were detected at 197 nm; progesterone, testosterone, methyl-testosterone were detected at 240 nm; estriol, estradiol-17β, estrone were detected with the fluorescence detector simultaneously, the excitation and emission wavelengths were 280 nm and 310 nm, respectively. The average spiked recoveries for seven sexual hormones were above 93.0% except that of progesterone was 79.5%. The relative standard deviations of seven sexual hormones were from 0.90% to 1.89%. The linear ranges of the determination were from 0.010 mg/L to 1.0 mg/L. The method is simple and accurate for simultaneously analyzing the seven sexual hormones in essential oil.

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Determination of human thrombin by an aptamer based on affinity capillary electrophoresis-laser induced fluorescence detection ZHANG Yuexia, SONG Maoyong, LI Tao, SAI Daojian, WANG Hailin 2009, 27 (3):  333-336.  Abstract ( 2836 )   [Full Text(HTML)] () PDF (298KB) ( 786 )   The method for the determination of human thrombin by an aptamer was developed based on capillary electrophoresis (CE) with laser induced fluorescence (LIF) detection. The concentration of thrombin was calculated through the peak area of the thrombin-aptamer complex, which was separated and detected by CE-LIF. Because of the binding favorable G-quartet conformation potentially involved in the specific aptamer, it was assumed that monovalent and bivalent cations promoting the formation of a stable G quadruplex conformation in the aptamer may enhance the binding of the aptamer and thrombin. Therefore, the effects of various metal cations on the binding of human thrombin and the aptamer were investigated. The results showed that the cations like K+ and Mg2+ could not stabilize the affinity complex. The linear range, detection limit and reproducibility were measured. The linear range was 0.25~10 nmol/L (r20.991), and the detection limit of thrombin was 55.6 pmol/L. Regarding the advantages of high efficiency and rapid separation, low sample consumption, and high sensitivity, CE-LIF is a potential and powerful alternative to conventional immunoaffinity assays in clinical diagnostics.

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Simultaneous determination of hexafluorophosphate and other trace impurity anions in ionic liquids by ion chromatography HU Zhongyang, PAN Guangwen, YE Mingli 2009, 27 (3):  337-340.  Abstract ( 2893 )   [Full Text(HTML)] () PDF (245KB) ( 844 )   A method was developed for the simultaneous determination of hexafluorophosphate and other trace impurity anions in ionic liquids by ion chromatography (IC). The sample was diluted with 70% (v/v) acetonitrile, filtrated by 0.22 μm nylon filter membrane, and then analyzed by IC. The analytical column was Dionex IonPac AS22 (250 mm×4 mm), carbonate-acetonitrile (70:30, v/v) was used as the eluent at a flow rate of 1.0 mL/min. The detection was performed by a Dionex DS6 conductivity detector. The quantitive analysis of external standard calibration curves was used. The linear ranges of the method for F~, Cl~, Br~ and PF~6 were 0.5~50 μg/L (r0.9999), 10~200 μg/L (r0.9998), 10~200 μg/L (r0.9999) and 0.9~45 mg/L (r0.9998), respectively. The average recoveries were 94.5%~100.5% with the relative standard deviations of 0.63%~1.03%. The detection limits (S/N3) were 0.5 μg/L, 2.0 μg/L, 5.0 μg/L and 0.9 mg/L for F~, Cl~, Br~ and PF~6, respectively. The method has been applied to determine hexafluorophosphate and other trace impurity anions in ionic liquids with satisfactory results.

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Determination of nitroaromatics and cyclo ketones in sea water by gas chromatography coupled with activated carbon fiber solid-phase micro-extraction MA Hanna, ZHU Mengya, WANG Yalin, SUN Tonghua, JIA Jinping 2009, 27 (3):  341-345.  Abstract ( 2940 )   [Full Text(HTML)] () PDF (828KB) ( 804 )   A gas chromatography (GC) coupled with solid-phase micro-extraction using a special activated carbon fiber (ACF) was developed for the analysis of 6 nitroaromatics and cyclic ketones, nitrobenzene (NB), 1,3-dinitrobenzene (1,3-DNB), 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), isophorone, 1,4-naphthaquinone (1,4-NPQ), in sea water samples. The sample was extracted for 30 min under saturation of NaCl at 1500 r/min and 60 ℃ in head space. The desorption was performance at 280 ℃ for 2 min. The linear ranges were from 0.01 to 400 μg/L. The limits of detection (LODs) were 1.4~3.2 ng/L. This method has been successfully applied to the determination of nitroaromatics and cyclic ketones in the sea water samples obtained from East China Sea. The concentrations of nitrobenzene, 1,3-dinitrobenzene and 2,6-dinitrotoluene in the sea water sample were 0.756, 0.944, 0.890 μg/L, respectively. The recoveries were 86.3%~101.8% with the relative standard deviations (RSDs) of 3.7%~7.8%. The method is suitable for analyzing nitroaromatics and cyclic ketones at low concentration levels in sea water samples.

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Determination of benzene and toluene in gasoline by two-dimensional gas chromatography and capillary column LI Jiwen, LI Wei, WANG Chuan 2009, 27 (3):  346-350.  Abstract ( 2766 )   [Full Text(HTML)] () PDF (518KB) ( 774 )   A novel two-dimensional gas chromatographic method, used for the determination of benzene and toluene in gasoline, was established by the capillary flow technology (Deans Switch) and universal capillary columns HP-5 (30 m×0.32 mm×0.25 μm) and Rtx-TCEP (30 m×0.25 mm×0.4 μm). Benzene, internal standard and toluene, which co-eluted with some saturated components from a non-polar column HP-5, were cut to a polar column Rtx-TCEP by Deans Switch and allowed to be fully resolved from saturated components. The linearity test showed that the correlation coefficient r2 values for benzene and toluene were 0.9994 and 0.9999, respectively. The results showed that the relative standard deviations (RSDs) of standard samples in five continued tests were within 1.5% and the recoveries of added standards tests were from 96.8% to 103.8%. This two-dimensional gas chromatographic method was compared to the standard analytical method for determining the concentrations of benzene and toluene in gasoline (SH/T 0713-2002). The results were in excellent agreement with the values obtained by SH/T 0713. The method is quick, simple and useful for the determination of benzene and toluene in gasoline.

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Automatic peak recognition and rapid resolution of chromatographic signals with a self-compiling program LIU Mingming, XIA Bingle, YANG Jun 2009, 27 (3):  351-355.  Abstract ( 2414 )   [Full Text(HTML)] () PDF (1062KB) ( 1141 )   Area reproduction method was introduced in combination with peak recognition algorithm based on high-order derivatives to automate the chromatogram division, peak recognition and rapid resolution. Durbin-Watson method and the criterion to distinguish the signal and noise were adopted to reduce the user interaction. The objective was that the operators should be able to perform this method with minimal experience and professional knowledge. The method is a useful tool by applying it to the resolution of model and real chromatographic signals.

Communications

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Determination of trace phthalates in beer by gas chroma-tography coupled with solid-phase microextraction using a calix［6］arene fiber GAO Jie, YANG Cai, YE Changwen, LI Xiujuan 2009, 27 (3):  356-358.  Abstract ( 2970 )   [Full Text(HTML)] () PDF (117KB) ( 783 )   A method based on headspace solid-phase microextraction/gas chromatography (HS-SPME/GC) for the determination of phthalates (PAEs) in beer using benzoxy-C［6］/OH-TSO coated fiber was developed. A Taguchi’s L25(56) orthogonal array design was employed to evaluate potentially significant factors and screen the optimum conditions for each analyte to ensure the highest extraction efficiency. The extraction for the determination of dimethyl phthalate (DMP) and diethyl phthalate (DEP) was carried out at 65 ℃ for 50 min with a constant stirring speed of 1250 r/min, that of dibutyl phthalate (DBP) and diamyl phthalate (DAP) was at 95 ℃ for 50 min with a speed of 624 r/min, and that of the other PAEs was at 105 ℃ for 60 min without agitation. Owing to the good selectivity and high sensitivity of this new calixarene fiber, the method enabled the quantification of PAEs at low μg/L level in beer media with good precisions and recoveries. The survey of three bottled beer samples showed that DBP and bis(2-ethylhexyl)-phthalate (DEHP) were the main PAEs found in beer and total phthalates concentrations were between 6.22 and 7.76 μg/L. The migration tests revealed that the high content of DEHP incorporated in PVC gaskets in the lids could be a potential source of PAEs contamination in bottled beer during transportation and storage.

Reviews

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Application of molecular imprinting technology in the separation and purification of active ingredients from natural products ZHOU Yuanyuan, MENG Zihui, DONG Meiling 2009, 27 (3):  359-363.  Abstract ( 2957 )   [Full Text(HTML)] () PDF (142KB) ( 2168 )   Active ingredients of natural products are in low content and difficult to be enriched. It is very difficult to purify natural product by general methods due to the coexistence of macromolecules, small molecule interferences, isomers and molecules with similar structures. Molecular imprinting is promising in preparing highly selective separation matrixes. Molecularly-imprinted polymers (MIPs) show good prospect in the purification of active ingredients from natural products. In this review, the application of molecular imprinting technology in the separation and purification of active ingredients, such as alkaloids, steroidals, polyphenols, and flavonoids, from natural products is summarized, and our work in the extraction of shikimic acid is also introduced.

Technical Notes

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Simultaneous determination of stimulant, narcotics and antiestrogen in urine by gas chromatography-nitrogen phosphorous detection QIU Lijun, ZHENG Xiaoyan, YOU Feiming, LIU Wei, ZHANG Jinzhang, ZHANG Lan 2009, 27 (3):  364-367.  Abstract ( 2427 )   [Full Text(HTML)] () PDF (298KB) ( 848 )   An easy, sensitive and quick method was established for simultaneously separating and determining stimulant, narcotics and antiestrogen in spiked human urine using gas chromatography-nitrogen phosphorous detection (GC-NPD). The urine sample was preprocessed by liquid-liquid extraction. Tert-butyl methyl ether and N-phenylamine were chosen as extraction solvent and internal standard for quantitation, respectively. That is, a standard stock mixture containing methylephedrine, meperidine, methadone, tamoxifen, fentanyl and N-phenylaniline was added into 5.0 mL urine samples and mixed uniformly, then 0.5 mL 5.0 mol/L NaOH, 3.0 g NaCl and 5.0 mL tert-butyl methyl ether were added and finally centrifuged. The extraction solution was dried under N2, redissolved by acetone and then determined by GC-NPD. The method showed the satisfactory linearity was between 0.022~20 mg/L, with the coefficient correlation from 0.9945 to 0.9998. The detection limits were in the range of 0.007~0.015 mg/L, and the average recoveries in spiked urine were between 75.8%~118.2% and the relative standard deviations were lower than 17.2%.

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Separation of hydroxybenzenes and amines by microcolumn liquid chromatography with imidazolium functionalized silica stationary phase LI Guang, NIU Jingang, LIU Xia, JIANG Shengxiang 2009, 27 (3):  368-371.  Abstract ( 2370 )   [Full Text(HTML)] () PDF (356KB) ( 891 )   Microcolumn liquid chromatography (μ-LC) has been received extensive attention in recent years because of several key advantages: the ability to work at very low flow rates, which leads to a significantly lower solvent consumption; the possibility to inject very low sample size; the enhanced detection performance with the use of concentration sensitive detection devices as a result of the strongly reduced chromatographic dilution during the separation process (mass sensitivity), the availability to hyphenate to mass spectrometry (MS), et al. A microcolumn liquid chromatographic system was set up. The chromatographic separations of some ordinary hydroxybenzenes and amines were performed with different mobile phases using the weak hydrophobic interaction of imidazolium functionalized silica stationary phase on a microcolumn (150 mm×0.25 mm). The results showed that the organic compounds could be well separated when a few organic solvents were added in the mobile phase, and some weak hydrophobic organic compounds such as phenols could be separated using only water as the mobile phase. For the advantages of microcolumn liquid chromatography, this experiment avoided or significantly reduced the use of organic solvents which contaminated the environment. This system provided a base for microcolumn liquid chromatography-mass spectrometry (μ-LC-MS).

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Determination of xanthohumol in beer by solid-phase extraction-high performance liquid chromatography WANG Ning, LI Yongxian, ZHENG Feiyun, LIU Chunfeng, LI Qi, GU Guoxian 2009, 27 (3):  372-375.  Abstract ( 2500 )   [Full Text(HTML)] () PDF (235KB) ( 689 )   A method for the determination of xanthohumol in beer using solid-phase extraction-high performance liquid chromatography (SPE-HPLC) has been developed. A Waters Sep-Pak C18 column was used to extract and clean-up the sample. The separation was achieved on a reversed-phase Agilent Zorbax Eclipse XDB-C18 (250 mm×4.6 mm, 5 μm) in a linear gradient, and the mobile phases were consisted of water (containing 0.1% formic acid) (A) and methanol (B) with a flow rate of 0.4 mL/min. In addition, the column temperature was maintained at 25 ℃. The detection wavelength was set at 370 nm. There was a good linear relationship (r21) in the range of 0.5~500 μg/L. The average recoveries were between 91.21% and 95.58% with the relative standard deviations less than 2%. The limit of detection was 0.24 μg/L and the limit of quantification was 0.80 μg/L. It was proved to be a convenient and accurate method for the analysis of xanthohumol content in beer.

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Determination of optical purity of α-phenylethylamine by high performance liquid chromatography with pre-column derivatization WANG Jinzhao, ZENG Su, WANG Danhua, HU Gongyun 2009, 27 (3):  376-378.  Abstract ( 2451 )   [Full Text(HTML)] () PDF (200KB) ( 929 )   A simple pre-column derivatization-high performance liquid chromatographic (HPLC) method was established for the determination of optical purity of α-phenylethylamine. The enantiomers of α-phenylethylamine were derivatized with 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate (GITC). The resulted diastereoisomers were separated on an Agilent Zorbax C18 column (250 mm×4.6 mm, 5 μm) with a mobile phase of methanol-phosphate buffer (1.36 g/L aqueous solution of potassium dihydrogen phosphate, adjusted to pH 3.0 with concentrated phosphoric acid) (58:42, v/v). The flow rate was set at 1.0 mL/min and the detection wavelength was set at 241 nm. The method was linear from 0.15~15.0 mg/L for both enantiomers. The limit of detection and the limit of quantification were 0.05 mg/L and 0.15 mg/L, respectively. The relative standard deviations (RSDs) of inter- and intra-day determination were below 0.5%. The method is easy to handle, accurate, and suitable for the quality control of the optical purity of α-phenylethylamine.

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Removal of the colloidal impurities in the purification of salvianolic acid B YANG Fan, HE Kejiang, LIU Ke, 2009, 27 (3):  379-381.  Abstract ( 2541 )   [Full Text(HTML)] () PDF (106KB) ( 730 )   The removal of the colloidal impurities in the purification of salvianolic acid B (SB) was carried out on a macroporous adsorption resin column with a modified elution method on the principle of combining frontal chromatography with displacement chromatography. Two serially connected columns were packed with macroporous adsorption resin in a certain proportion. The latter column was eluted with 50% methanol, when the colloidal impurities reached saturation adsorption in the former column. Comparative study suggested that the SB product was superior to that from the routine method with the weighted average purity risen from 59.6% to 64.5%, and the recovery from 69.75% to 80.0%. The ethanol concentration was lowered in the eluent. The method is simple and can be used for the production of SB in large scale.