List of Issues

Chinese Journal of Chromatography
2009, Vol. 27, No. 4
Online: 30 July 2009

Previous Issue    Next Issue



For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Communications

Select

Microchip free flow isoelectric focusing with immobilized pH gradient on monolithic materials HAN Bin, WANG Pingli, ZHANG Lihua, QU Feng, LIANG Zhen, DENG Yulin, ZHANG Yukui 2009, 27 (4):  383-386.  Abstract ( 2276 )   [Full Text(HTML)] () PDF (1336KB) ( 620 )   Microchip free flow electrophoresis (μFFE) is a significant microscale technique for the continuous pre-fractionation and the preparation of valuable biological samples. In our recent work, monolithic polyacylamide (PAM) materials were polymerized in microchamber by ultraviolet (UV) initiated polymerization. With the further immobilization of a stable pH gradient on the monolith, a novel microchip free flow isoelectric focusing (μFF-IEF) with monolithic immobilized pH gradient (M-IPG) materials was developed, by which fluorescein-5-isothiocyanate (FITC) labeled glycin, proline and lysine, with a minimum pI difference of 0.33 units, were well separated with a resolution higher than that performed by traditional μFF-IEF. Our experimental results demonstrate that by μFF-IEF with M-IPG, not only the interference of mobile carrier ampholytes in buffer, usually indispensable in traditional μFF-IEF, on the further separation by other techniques and the identification by mass spectrometry (MS) could be avoided, but also the improved resolution and detection sensitivity could be obtained compared with traditional μFF-IEF. Therefore, such a novel technique might be promising in microscale consecutive separation and preparation of samples.

Select

Classification of the cell lines in the extraction of intracellular metabolites based on ultra performance liquid chromatography-time of flight mass spectrometry LI Hui, YU Zhiguo, ZU Xuyu, LIU Feng, JIN Yibao, JIANG Yuyang, LIU Hongxia 2009, 27 (4):  387-390.  Abstract ( 2569 )   [Full Text(HTML)] () PDF (267KB) ( 747 )   Intracellular metabolites can reflect the physiological state of cells. Ultra performance liquid chromatography/time of flight mass spectrometry (UPLC-TOF MS) is a relatively new technique for the separation of complex samples. The aim of this work is to assess the feasibility of metabonomics in cell line sorting. In the work, a total of 5 cell line samples were analyzed by using UPLC-TOF MS and small molecules metabolite profiles from the extraction of intracellular metabolites were obtained. Principal component analysis (PCA) models were used to extract meaningful information from the complex biological samples. The cell line discrimination was highly improved by PCA. These preliminary results suggested that UPLC/MS coupled with pattern recognition show promise for metabonomics. It is a potential and very promising technology for the classification of the cell lines.

Articles

Select

Determination of 107 pesticide residues in vegetables using off-line dispersive solid-phase extraction and gas chromatography-tandem mass spectrometry SHEN Weijian, YU Keyao, GUI Qianwen, JIANG Yuan, ZHAO Zengyun, SHEN Chongyu, WU Bin, CHU Xiaogang 2009, 27 (4):  391-400.  Abstract ( 2994 )   [Full Text(HTML)] () PDF (450KB) ( 1001 )   A screening method was developed for the determination of 107 pesticide residues in vegetables using off-line dispersive solid-phase extraction (DSPE) and gas chromatography-tandem mass spectrometry (GC-MS/MS). The pesticides interested were extracted from the samples with acetonitrile (saturated by n-hexane) containing 1% acetic acid and simultaneously separated by liquid-liquid partitioning with adding anhydrous magnesium sulfate plus sodium acetate following by a simple cleanup step known as dispersive solid-phase extraction. The extracts were determined by GC-MS/MS using external standard method. The method was reliable and stable that the recoveries of almost all pesticides were in the range from 60% to 130% at the spiked level of 10 μg/kg into four vegetable matrixes (garlic, green bean, radish and spinach) and the relative standard deviations (RSDs) were all not more than 15.3%. The linearity of the method was good between 0.05 mg/L and 1 mg/L, and all limits of quantification (LOQs) less than 10 μg/kg. The method is selective with no interference, especially in the complicated garlic matrix.

Select

Determination of residues of cyromazine and its metabolite melamine in chickens by gas chromatography-mass spectrometry ZHU Xinle, LIU Qi, LI Dan, WANG Shuhuai, WANG Xia 2009, 27 (4):  401-405.  Abstract ( 2608 )   [Full Text(HTML)] () PDF (4239KB) ( 749 )   A gas chromatography-mass spectrometric (GC-MS) method has been established for the determination of cyromazine and its metabolite melamine in chickens. The homogenized tissue samples added with melamine-15N3 were extracted with acidic acetonitrile-water solution, and defatted with dichloromethane. The samples were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), after solid-phase extraction (SPE) which was performed on Oasis MCX cartridges, and then detected by GC-MS. Cyromazine was quantified by an external standard method, and melamine by an internal standard method using melamine-15N3. The results indicated that the linearities of cyromazine and melamine were within the range of 100~1000 μg/L, and their limits of quantification (LOQ) were 20 μg/kg. The mean recoveries of chicken samples fortified at three concentrations of 20, 40 and 80 μg/kg were within the range of 75%~110%. The relative standard deviations (RSDs) of intra- and inter- batch were less than 10% and 15%, respectively. The application of this method was further demonstrated by analyzing 10 real samples which were brought from local markets. The results show that this method is simple, rapid, sensitive and specific. It is appropriate for the identification and quantification of cyromazine and its metabolite melamine in chickens.

Select

Simultaneous analysis of 7 fluoroquinolone residues in chicken muscle by ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry GUO Wei, LIU Yong, LIU Ning 2009, 27 (4):  406-411.  Abstract ( 2636 )   [Full Text(HTML)] () PDF (452KB) ( 600 )   A confirmative method of ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) for the simultaneous determination of 7 fluoroquinolone residues (norfloxacin (NOR), ciprofloxacin (CIP), danofloxacin (DAN), enrofloxacin (ENR), ofloxacin (OFL), sarafloxacin (SAR) and marbofloxacin (MAR)) in chicken muscle was developed. The sample was extracted with acidified acetonitrile, defatted with n-hexane, and purified by an HLB solid phase extraction cartridge. The UPLC separation was performed on an ACQUITY UPLCTM BEH C18 column (50 mm×2.1 mm, 1.7 μm) utilizing a gradient elution program of acetonitrile and water (containing 0.1% formic acid) as the mobile phase. The identification and quantification were achieved by using ESI-MS/MS in positive ion mode and multiple reaction monitoring (MRM). The linear ranges were from 5 to 100 μg/kg with the correlation coefficients above 0.99 for all the 7 fluoroquinolones. The average recoveries spiked at the 3 concentration levels of 5, 25, 50 μg/kg ranged from 79.2% to 108.6% with the relative standard deviations of 4.2%~8.9%. The limits of detection were 0.2~1.4 μg/kg. The method was proved to be good reproducibility, high sensitivity, rapid, reliable and suitable for the simultaneous determination of multi-residues of fluoroquinolones in chicken muscle.

Select

Simultaneous determination of tetracyclines, sulfonamides and quinolones residues in chicken livers by ultra performance liquid chromatography-tandem mass spectrometry GUO Liming, ZHU Kui, JIANG Haiyang, LI Jiancheng, LI Xiaowei, DING Shuangyang, 2009, 27 (4):  412-416.  Abstract ( 2896 )   [Full Text(HTML)] () PDF (402KB) ( 1115 )   An analytical method for the simultaneous determination of 3 tetracyclines, 10 sulfonamides and 8 quinolones in chicken livers by ultra performance liquid chromatography coupled with tandem quadrupole mass spectrometry (UPLC-MS/MS) in positive ion mode with multiple reaction monitoring (MRM) has been developed and validated. A total of 2 g homogenized sample of chicken livers was placed in a 50 mL polypropylene tube, and 1 mL of McIlvaine buffer and 4 mL of acetonitrile were added. After stirring and centrifuging for 5 min at 4000 r/min, the supernatant was collected and the remains was extracted by 5 mL acetonitrile. The supernatant was merged together and evaporated to dryness under a steam of nitrogen at 60 ℃. The residue was dissolved with 4 mL of phosphoric acid-triethylamine buffer-acetonitrile (85:15, v/v) and 4 mL of n-hexane. After stirring for 1 min and centrifuging for 5 min at 4000 r/min, the under layer solution was analyzed using UPLC-MS/MS. The satisfactory recoveries (66.8%~128.5%) of all the veterinary drugs were demonstrated at spiked levels of 5, 10 and 50 μg/kg with the overall relative standard deviations (RSDs) for intra-day and inter-day of the 21 analytes less than 20.5%. The limit of detection (LOD) and the limit of quantification (LOQ) were 2 μg/kg and 5 μg/kg, respectively for each drug. This method has good stability, lower detection limits and can be used as a conclusive evidence method of these drug residues in chicken livers.

Select

Determination of 9 cephalosporin drug residues in beef by ultra performance liquid chromatography-tandem mass spectrometry BAI Guotao, CHU Xiaogang, PAN Guoqing, LI Xiuqin, YONG Wei 2009, 27 (4):  417-420.  Abstract ( 2355 )   [Full Text(HTML)] () PDF (143KB) ( 1227 )   A confirmative method to determine 9 cephalosporin residues in beef by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. The sample was homogenized and extracted with acetonitrile and water for 1 min at 14000 r/min, centrifuged at 10000 r/min and 4 ℃ for 10 min. A total of 2 mL saturated sodium chloride solution was added to avoid foaming during the acetonitrile evaporation, the acetonitrile was evaporated below 37 ℃ using a rotary evaporator, and then cleaned up on an Oasis HLB(500 mg, 6 mL) SPE column by washing with 5 mL water and eluting with acetonitrile-water (7:3, v/v). The eluate was blown to dryness under a stream of nitrogen and adjusted to 3.0 mL with water. The separation was carried out on an ACQUITY UPLCTM BEH C18 column within 5 min, analyzed by UPLC-MS/MS system with external standard method. The limits of quantification (LOQs) of cefuroxime, ceftiofur and cefalonium were 10, 0.5 and 0.5 μg/kg, respectively; the LOQs of other cephalosporins were 1.0 μg/kg. The recoveries of cephalosporins ranged from 74.2% to 119% and the relative standard deviations (RSDs) ranged from 2.9% to 15% for the spiked beef sample. The method is quick, easy, very sensitive and suitable for the determination of cephalosporin residues in beef.

Select

Determination of pyriproxyfen residue in vegetables and fruits by liquid chromatography-tandem mass spectrometry ZHAO Guangyu, GUO Dehua, ZHAO Shanzhen, SHENG Yonggang, DENG Xiaojun 2009, 27 (4):  421-424.  Abstract ( 2848 )   [Full Text(HTML)] () PDF (246KB) ( 645 )   A method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established for the determination of pyriproxyfen residue in vegetables and fruits. The pyriproxyfen residue in the sample was extracted by acidified acetonitrile with the presence of sodium acetate buffer, and cleaned up by PSA (primary secondary amine) sorbent, and the separation was performed by ultrafast liquid chromatography (UFLC) on a CAPCELL PAK C18 column (50 mm×2.0 mm, 3 μm) and the gradient elution of acetonitrile (containing 0.1% formic acid) and 2 mmol/L ammonium acetate solution (containing 0.1% formic acid) at a flow rate of 0.3 mL/min. The calibration curve was linear between the peak area and the concentration of 2.5~50 μg/L with the correlation coefficient more than 0.9999. The limit of quantification of pyriproxyfen was 5 μg/kg. The average recoveries spiked at three concentrations of 5, 50 and 100 μg/kg ranged 84.7%~91.5%. The relative standard deviations (n10) were all less than 10%. The method is selective without interference and suitable for the determination of pyriproxyfen residue in vegetables and fruits.

Select

Identification and determination of major constituents in Polygonum cuspidatum Sieb. et Zucc. by high performance liquid chromatography/electrospray ionization-ion trap-time-of-flight mass spectrometry DONG Jing, WANG Hong, WAN Leren, HASHI Yuki, CHEN Shizhong 2009, 27 (4):  425-430.  Abstract ( 2945 )   [Full Text(HTML)] () PDF (13933KB) ( 716 )   A facile method using high performance liquid chromatography/electrospray ionization-ion trap-time-of-flight mass spectrometry (HPLC/ESI-IT-TOF MS) has been established for the analysis of multiple constituents in Polygonum cuspidatum Sieb. et Zucc. Six chemical standards including emodin, chrysophanol, physcion, rhein, aloe-emodin and polydatin were studied systematically and their fragmentation pathways were concluded. The methanol extract of Polygonum cuspidatum Sieb. et Zucc. was separated and analyzed by HPLC/ESI-QIT-TOF MS system in negative ion mode. A total of 10 constituents were identified or tentatively characterized with supporting results on the fragmentation pathways of 6 chemical standards and relative references. These constituents are mainly anthraquinones, stilbenes, torachryson and their derivatives, including resveratroloside, polydatin, emodin-8-O-glucoside, resveratrol, torachryson-8-O-glucoside, emodin-1-O-glucoside, torachryson-8-O-(6′-acetyl)glucoside (newly discovered), physcion-8-O-glucoside, physcion-8-O-(6′-acetyl)glucoside (newly discovered) and emodin. It is an extremely simple way by using HPLC/ESI-IT-TOF MS to provide chemical information concerning the constituents in herbal medicines and making the identification results more convinced.

Select

Preparation and evaluation of octadecanethiol modified gold microspheres in capillary liquid chromatography and pressurized capillary electrochromatography as stationary phase ZHAO Zhenzhen, QU Qishu, ZHANG Xinxin, GU Xue, WANG Yan, YAN Chao 2009, 27 (4):  431-435.  Abstract ( 2541 )   [Full Text(HTML)] () PDF (845KB) ( 616 )   Gold microspheres modified with octadecanethiol as chromatographic stationary phase were prepared. The particles were characterized by the scanning electron micrograph (SEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis and nitrogen adsorption analysis. The average diameter, the surface area and the average pore diameter were 3.5 μm, 49.0 m2/g and 5.0 nm, respectively. The IR spectra demonstrated that C18 was bonded to the surface of gold microspheres with the carbon content of 0.56%. Using these microspheres as stationary phase, a 19 cm section of a total length of 36 cm capillary (100 μm i.d.) was packed electrokinetically, and the evaluations in capillary liquid chromatography and pressurized capillary electrochromatography were performed. The mobile phases (80% methanol) with extreme pH values (pH 1.0 or pH 12.0) were used to flush the column for 140 h. In order to investigate the chemical stability of the column, the retention factors before and after flushing were calculated and compared based on the experimental results. There was no remarkable deterioration on the retention factors after flushing, which demonstrated the column was stable under strong acidic and basic conditions. Five neutral compounds and three alkaline compounds were separated using capillary liquid chromatography to examine the retention behavior of the column, and over 50000 theoretical plates per meter and acceptable symmetry peaks were obtained. The pressurized capillary electrochromatographic properties of the column were investigated using a separation of the mixture of aniline and benzoic acid, and the separation was obtained when a 5 kV positive or negative voltage was applied. The research work confirmed the feasibility of using the octadecanethiol modified gold microspheres as a novel stationary phase for capillary liquid chromatography and pressurized capillary electrochromatography.

Select

Selective enrichment of iridoid glucosides in Hedyotis diffusa Willd. by tandem solid phase extraction ZHANG Feng, GUO Zhimou, ZHANG Feifang, XUE Xingya, LIANG Xinmiao, 2009, 27 (4):  436-441.  Abstract ( 2721 )   [Full Text(HTML)] () PDF (497KB) ( 695 )   A method for selective enrichment of iridoid glucosides in Hedyotis diffusa Willd. by tandem solid phase extraction (SPE) was developed. Oligo(ethylene glycol) (OEG) is a novel type of separation material made in this laboratory. The differences of the surface chemical structures between OEG material and ODS material resulted in their different retention capabilities for iridoid glucosides. Based on the differences, an OEG-ODS solid phase extraction method was designed for selective enrichment of iridoid glucosides. The water extract (150.28 mg) of Hedyotis diffusa Willd. was precipitated by ethanol, and an aliquot (27.03 mg) of the product from the supernatant solution was loaded onto an OEG cartridge and rinsed by 5 mL water. Then, the rinsing solution was loaded onto an ODS cartridge. After it was washed by 5 mL water and eluted by 5 mL methanol, 4.01 mg final product was obtained from the methanol eluent. All the products were characterized by ultra performance liquid chromatography (UPLC), and 14 representative peaks of iridoid glucosides were found. The enrichment results were proved effective by directly comparing the chromatograms each step. To further characterize the enrichment efficiency, the changes of the peak area of iridoid glucosides were investigated. The results showed that the content of 14 iridoid glucosides in the final product reached 6.10 times its original proportion in water extraction product and their recovery was 50.1% on average. Therefore, the iridoid glucosides can be enriched by the tandem solid phase extraction method from water extracting-ethanol precipitating solution of Hedyotis diffusa Willd. with a good selectivity and an acceptable recovery. The proposed method has the advantages of high enrichment efficiency and simple operation.

Select

Optimization of high performance liquid chromatographic method for analysis of extract of Fructus schisandrae chinensis DAI Yuntao, JIN Gaowa, QIN Xuemei, XUE Xingya, ZHANG Feifang, LIANG Xinmiao, 2009, 27 (4):  442-446.  Abstract ( 2339 )   [Full Text(HTML)] () PDF (534KB) ( 656 )   For the separation of the complex system of alcohol fraction of Fructus schisandrae chinensis, complex sample analysis system software (CSASS) was utilized to optimize the high performance liquid chromatographic (HPLC) conditions. The HPLC retention parameters a and c, and the peak shape parameters σ and W1/2 were obtained accurately and rapidly by analyzing 4 linear gradient elutions. Based on the 4 parameters, the chromatogram in any gradient condition could be simulated and predicted precisely. The HPLC optimization method was developed using moved overlapping separation ranging map and simulated chromatogram technology. The HPLC analysis of the alcohol fraction of Fructus schisandrae chinensis could be finished in 40 min, and good resolution for components with general or low abundance was achieved. This method could be used to predict retention times and peak shapes of components in Fructus schisandrae chinensis. And based on the precise predicted results, the optimized separation conditions can be obtained.

Select

Development of high performance liquid chromatographic fingerprints of liposoluble constituents in donkey- hide glue and tortoise-shell glue YU Haiying, ZHOU Yongyan, CHENG Xiumin 2009, 27 (4):  447-452.  Abstract ( 3274 )   [Full Text(HTML)] () PDF (372KB) ( 790 )   A sensitive and specific method with high performance liquid chromatographic fingerprints was developed for controlling the quality of donkey-hide glue and tortoise-shell glue according to the liposoluble constituents. The samples were prepared with the liquid-liquid-liquid three-phase static extraction. The liposoluble constituents were analysed by reversed-phase high performance liquid chromatography with a gradient program and detected at 205 nm. The chromatograms were evaluated by similarity and cluster analysis. The common peaks of two glues were marked respectively. The differences between two glues were revealed by similarity and cluster analysis. The method has good repeatability and stability, and can be served as the means to identify different kinds of animal glue.

Select

High performance liquid chromatographic fingerprints of ethanol and cyclohexane extracts of Rhizoma Drynariae and quantitative analysis of index components based on principal component analysis LI Xiaohong, XIONG Zhili, YU Mingyang, LU Xiumei, YU Xiao, LI Famei 2009, 27 (4):  453-457.  Abstract ( 2684 )   [Full Text(HTML)] () PDF (350KB) ( 636 )   The method of fingerprint analysis and quantification of Rhizoma Drynariae was performed by high performance liquid chromatography (HPLC). The sample was extracted by ethanol and cyclohexane. The extract was separated on a Diamonsil C18 column, and gradiently eluted with acetonitrile and 0.4% glacial acetic acid at 25 ℃. The fingerprint analysis of ethanol and cyclohexane extracts of Rhizoma Drynariae using HPLC profiling was established. The contents of naringin, neoeriocitrin and E-4-O-β-D-glucopyranosyl caffeic acid in nineteen batches of samples were determined simultaneously. Significant differences were observed between genuine and fake samples in the principal component analysis (PCA) score plot, finding four potential index components in the PCA loading plot as well. Three important potential index components were naringin, neoeriocitrin and E-4-O-β-D-glucopyranosyl caffeic acid, and the contents of them in ten genuine batches were 6.36~10.1 mg/g, 5.14~9.21 mg/g and 1.87~3.19 mg/g, respectively. Combining determination of the index components with fingerprint analysis of Rhizoma Drynariae using HPLC profiling, the quality of Rhizoma Drynariae can be assessed better.

Select

Determination of alkylphenols and alkylphenol polyethoxylates in textiles by normal-phase high performance liquid chromatography and solid-phase extraction Lv Chunhua, CHEN Xiaomei, LIU Haishan 2009, 27 (4):  458-462.  Abstract ( 2545 )   [Full Text(HTML)] () PDF (493KB) ( 771 )   A method for the simultaneous determination of alkylphenols (AP) and alkylphenol polyethoxylates (APnEO)(n2~16) in textiles was developed by normal-phase high performance liquid chromatography (NP-HPLC). The residues of AP and APnEO in the samples were extracted with methanol by Soxhlet extraction. The pretreatment conditions such as extraction solvents, extraction methods and clean-up methods were optimized. The sample was purified by an HLB solid-phase extraction column and separated on an amino column (250 mm×4.6 mm, 5 μm) with hexane-isopropanol (90:10, v/v) and isopropanol-water (90:10, v/v) as mobile phases at a flow rate of 1.0 mL/min and determined by a fluorescence detector. AP and each APnEO oligomer were separated successfully within a reasonable time with gradient elution, which are difficult to be separated by using conventional reversed-phase high performance liquid chromatography (RP-HPLC). The detection limit was 1.0 mg/kg for each analyte. The recoveries ranged from 90.4% to 104.1% with the relative standard deviations (RSDs) ranged from 0.64% to 4.21%. This method is suitable for the determination of alkylphenols and alkylphenol polyethoxylates in textiles.

Select

Determination of diflubenzuron and triflumuron residues in greasy wool by accelerated solvent extraction technique and high performance liquid chromatography FAN Yuanmu, HUANG Shaotang, YU Xuejun, GU Xiaojun, QIU Yajun, CHEN Shubing, FANG Keteng, CHEN Jun 2009, 27 (4):  463-466.  Abstract ( 2419 )   [Full Text(HTML)] () PDF (252KB) ( 638 )   A method for the determination of diflubenzuron and triflumuron residues in greasy wool was developed by high performance liquid chromatography (HPLC) coupled with accelerated solvent extraction (ASE). The diflubenzuron and triflumuron residues were extracted with acetonitrile saturated with n-hexane at 80 ℃ and 10.34 MPa. The extract was pretreated by a series of procedures such as freezing-lipid filtration, concentration and purification by solid-phase extraction prior to the determination with HPLC. The target analytes were separated on a Waters Atlants dC18 column (250 mm×4.6 mm, 5 μm), gradiently eluted with acetonitrile and water as the mobile phases and detected by a photodiode array detector (DAD) at 254 nm. The linear ranges were 0.1~10.0 mg/L. There were good linearity between the peak areas and concentrations in the linear range for the analytes, and the correlation coefficients of diflubenzuron and triflumuron were higher than 0.9999. The limits of quantification for diflubenzuron and triflumuron were 0.05 and 0.04 mg/kg (S/N≥10), respectively. The method is simple, rapid, sensitive and suitable for preliminary screening of diflubenzuron and triflumuron residues in greasy wool.

Select

Comparative enantiomer separation of β-blockers on polysaccharide derived chiral stationary phases using high performance liquid chromatography with acid or base additive in the mobile phases HUANG Hu, JIN Jingyu, LEE Wonjae 2009, 27 (4):  467-471.  Abstract ( 2371 )   [Full Text(HTML)] () PDF (6476KB) ( 741 )   The liquid chromatographic enantiomer separation of β-blockers on several polysaccharide derived chiral stationary phases (CSPs) (Chiralpak AD, Chiralcel OD, Chiralpak IA and Chiralpak IB) was performed and compared in the normal phase mode using hexane-ethanol in the presence of acid or base additives. The chromatographic conditions were 10%~30% (v/v) ethanol-hexane containing 0.1% trifluoroacetic acid or triethylamine as the mobile phase at the flow rate of 1.0 mL/min with the detection at 254 nm. The lower enantioselectivities and the shorter retention times on amylose derived CSPs (Chiralpak AD and Chiralpak IA) using the mobile phase with acid additive than those with base additive were shown, except for slightly longer retention times of metoprolol and propranolol on Chiralpak AD. The greater enantioselectivities and the shorter retention times on cellulose derived CSPs (Chiralcel OD and Chiralpak IB) using the mobile phase with acid additive than those with base additive were shown, especially, Chiralcel OD showed dramatically enhanced enantioselectivites using the mobile phase with acidic additive. Also, it was shown that the greater enantiomer separation of β-blockers on Chiralcel OD was achieved using the mobile phases with the higher concentration acid additive.

Select

Development and application of screening method for asparagine synthetase B inhibitors by high performance liquid chromatography ZHANG Ji, YU Dan, XIANG Wensheng, FAN Zhijin, WANG Xiangjing 2009, 27 (4):  472-475.  Abstract ( 2098 )   [Full Text(HTML)] () PDF (255KB) ( 525 )   A screening method for asparagine synthetase B (AS-B) inhibitors by reversed-phase high performance liquid chromatography (RP-HPLC) has been established. The contents of asparagines produced in the reaction system can be analyzed by HPLC after the derivatization with 1-fluoro-2,4-dinitrobenzene (DNFB) and used to calculate the total activity of AS-B. The sample was separated on an Agilent C18 column (250 mm×4.6 mm, 5 μm) at the temperature of 30 ℃ with the elution of 50 mmol/L sodium acetate buffer (pH 6.2)-acetonitrile (15:85, v/v) as mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 365 nm. The enzyme reaction system consisted of 100 mmol/L Tris （tris(hydroxymethyl)aminomehane）-HCl buffer (pH 8.0), 100 mmol/L NaCl, 10 mmol/L MgCl2, 5 mmol/L adenosine triphosphate (ATP), 10 mmol/L L-aspartate, 10 mmol/L L-glutamine and 2 μg recombinant soybean AS-B (1 mL of the total volume), then mixed for 1 min and incubated for 15 min at 37 ℃. After quenching with ethanol and centrifugation, the supernatant was derivatized by DNFB and then separated by HPLC. The amino acids in the reaction system were baseline separated within 6 min. The quantitative analysis of AS-B inhibition was performed by determining its dynamic parameters. The inhibitor L-glutamic acid γ-methyl ester was used in the enzyme reaction system to test this method and its inhibition constant obtained was close to the literature value. The established method is fast, accurate, sensitive and suitable for high throughput screening AS-B inhibitors.

Select

Application of matrix solid-phase dispersion for the determination of phoxim in crucian carp samples by high performance liquid chromatography LIU Qian, LIU Xiaoyu, QIU Chaokun, WANG Xiaobao, REN Hongmin 2009, 27 (4):  476-479.  Abstract ( 2610 )   [Full Text(HTML)] () PDF (355KB) ( 739 )   An analytical method was developed for the determination of phoxim residue in the muscle of crucian carp, which involved matrix solid-phase dispersion (MSPD) followed by high performance liquid chromatography (HPLC) with diode array detector. Under optimal conditions, 0.5 g tissue sample was dispersed with 1.5 g Florisil and 0.5 g anhydrous sodium sulphate, transferred to a cartridge. The cartridge was eluted with 25 mL acetone-hexane (40:60, v/v). The phoxim was separated on an ODS column (250 mm×4.6 mm, 5 μm) with methanol-water (50:50, v/v) as the mobile phase at the flow rate of 0.6 mL/min, then detected by a diode array detector at 270 nm. The injection volume was 20 μL. The linear range of the method was 0.01~10 mg/L and the detection limit was 3.3 μg/kg. The average recoveries spiked at the levels of 0.05, 0.1, 1 mg/kg ranged from 88% to 112% with the relative standard deviations (RSDs) of 1.1% ~6.3%. The method is quick, simple and can meet the requirement of the analysis of pesticide residues.

Select

Determination of solubility parameter for dicationic ionic liquid by inverse gas chromatography WANG Jun, ZHANG Zhenzhen, YANG Xuzhao, LI Gangsen 2009, 27 (4):  480-483.  Abstract ( 2615 )   [Full Text(HTML)] () PDF (226KB) ( 696 )   An inverse gas chromatographic method has been used to measure the solubility parameter of the dicationic ionic liquid, 1,10-bis(3-methylimidazolium-1-yl)decane hexafluorophosphate ［C10(MIM)2］［PF6］2, at the absolute temperatures from 343.15 K to 363.15 K. The test probe solvents were n-octane, n-dodecane, n-tetradecane, and n-hexadecane. The specific retention volumes of the solvents (V0g), the molar enthalpy of sorption (ΔHS1), the partial molar enthalpy of mixing at infinite dilution (ΔH∞1), the molar enthalpy of vaporization (ΔHv), the activity coefficients at infinite dilution (γ∞12), Flory-Huggins interaction parameters (χ∞12) between ［C10(MIM)2］［PF6］2 and probe solvents were obtained. The solubility parameter (δ2) of ［C10(MIM)2］［PF6］2 was determined as 15.01 (J\5cm~3)1/2, which was of great importance to the study of the solution behavior and application for ionic liquid.

Select

Efficient protein extraction method from apple leaves for apple proteomic analysis using two-dimensional electrophoresis analysis ZENG Guangjuan, LI Chunmin, ZHANG Xinzhong, TENG Yunlong, DONG Wenxuan 2009, 27 (4):  484-488.  Abstract ( 2214 )   [Full Text(HTML)] () PDF (1672KB) ( 755 )   In order to develop an efficient protein extraction method suitable for apple leaf proteomic analysis, four extraction methods for total protein in apple leaves were compared, including trichloroacetic acid (TCA)/acetone precipitation, dithiothreitol (DTT)/acetone method, tri(hydroxymethyl)aminomethane (Tris-HCl) method and the modified Tris-HCl method. During the two-dimensional electrophoresis (2-DE), the first dimension electrophoresis was performed on a 7 cm strip with pH 3~10 linear immobilized pH gradient (IPG) and the second one was performed on 12.5% polyacrylamide gels of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The proteins were detected by silver staining. The results showed that 140, 215, 181 and 616 protein spots were detected on 2-DE gels, respectively. The modified Tris-HCl method was the most appropriate for apple leaf proteomic analysis because of the highest resolution and no apparent vertical or horizontal streaking on the 2-DE map. In order to testify the effect of the modified Tris-HCl method on the apple leaf protein extraction, 2-DE maps were established by using 18 cm strips with linear IPG in pH range of 3~10. After 2-DE separation and Coomassie Brilliant Blue R-250 (CBB R-250) staining, about 455 spots were detected, and the relative molecular masses of most proteins were distributed in the range of 14000~66000 which were free of smearing or streaking. So it was once again proved that the modified Tris-HCl method can be used in apple leaf proteome analysis.

Select

Improvement of reproducibility in capillary electrophoretic characterization of rhubarb by normalization of migration time ZHANG Hongyi, GE Lijuan, CHEN Hui, JING Cong, SHI Zhihong 2009, 27 (4):  489-493.  Abstract ( 2029 )   [Full Text(HTML)] () PDF (388KB) ( 461 )   The principle of the normalization of migration time and its application on the traditional Chinese medicine (TCM) analysis by capillary electrophoresis (CE) are presented. It is the core of the normalization of migration time that the fluctuation of apparent migration velocity for each component at different runs is attributed to the difference of electroosmotic flow velocity. To transform migration time (t) to normalized migration time, one peak or two peaks in the original electropherogram are selected as internal peak. The normalization of migration time is therefore classified into two types based on the number of selected internal peaks, one-peak and two-peak approaches. The migration times processed by one-peak normalization and by two-peak normalization are conducted by the following equations, respectively: (t′ i)j1/｛1/(ti)j~［1/(tistd)j~1/(tistd)1］｝ and (t″ i)j1/｛1/(ti)j~｛［1/(tistd,1)j~1/(tistd,1)1］+［1/(tistd,end)j~1/(tistd,end)1］｝/2｝, where (t′ i)j and (t″ i)j are the normalized migration times obtained by one-peak and two-peak approaches in the jth run for component i, respectively; (ti)j and (tistd)j are the migration times in the jth run for component i and the selected internal standard in the sample, respectively; (tistd,1)j and (tistd,1)1 are the migration times for the first peak selected as internal peak in the jth run and the first run, respectively; (tistd,end)j and (tistd,end)1 are the migration times for the last peak selected as internal peak in the jth run and the first run, respectively. One of the commonly used traditional Chinese medicines (TCM), rhubarb, was chosen as a model to verify the advantage of migration time normalizations in improving reproducibility of CE. Both of the experiments, the five parallel micellar electrokinetic chromatography for rhubarb extract and the capillary zone electrophoresis for the samples prepared by mixing rhubarb extract with various solutions, showed RSD(t″)

Select

Capillary electrophoresis fingerprints of Compound Danshen Dropping Pill SUN Guoxiang, SONG Yuqing 2009, 27 (4):  494-498.  Abstract ( 3138 )   [Full Text(HTML)] () PDF (433KB) ( 519 )   To establish capillary electrophoresis fingerprint (CEFP) of Compound Danshen Dropping Pill (CDDP) by capillary zone electrophoresis, the electrophoretic separation was performed by using a 75 cm×75 μm (the effective length of 63 cm) uncoated fused silica capillary with 50 mmol/L sodium borate and 200 mmol/L boric acid (1:1, v/v) containing 1.1% triethylamine as the background electrolyte. The running voltage was 18 kV while the detection wavelength was set at 290 nm. The CEFPs were produced by the electropherograms from 10 batches of CDDP and the 8 co-possessing peaks were selected as the fingerprint peaks of CDDP’s CEFP by choosing protocatechualdehyde peak as the referential peak. The quality of CDDP was evaluated by systematic quantified fingerprint method through assessing the CEFP. Ten batches of CDDP were classified by systematic quantified fingerprint method. Among the 10 batches of CDDP, the contents of 1 batch were obviously lower while the others were almost similar. The CEFPs of CDDP were established with good precision and reproducibility, which can be served as a novel reference to identify and control the quality of CDDP.

Select

Determination of phosphate, pyrophosphate, metaphosphate and total phosphorus in seafoods by ion chromatography ZHONG Zhixiong, LI Gongke 2009, 27 (4):  499-504.  Abstract ( 3360 )   [Full Text(HTML)] () PDF (446KB) ( 923 )   A method for the determination of phosphate, pyrophosphate, metaphosphate and total phosphorus in seafoods by ion chromatography (IC) was developed. The samples for the determination of phosphate, pyrophosphate, metaphosphate were extracted by 100 mmol/L NaOH solution at room temperature; the samples for the determination of total phosphorus were digested by incineration at high temperature; and then solid phase extraction (SPE) column was used to eliminate the interferences. The separation was carried out on an IonPac AS11-HC analytical column (250 mm×4 mm) and an IonPac AG11-HC guard column (50 mm×4 mm) using 30~80 mmol/L KOH gradient elution at a flow rate of 1.0 mL/min at 35 ℃, coupled with a suppressor-type conductivity detector. Under optimum conditions, the measurement could be completed within 20 min. The effects of pH value, organic solvent and coexisted ions were investigated. The linear range was 0.3~60 mg/L, the detection limits were from 2.1 mg/kg to 2.3 mg/kg, and the relative standard deviations were from 1.6% to 2.6%. The method was applied to the determination of anions in fish and shrimps with the recoveries of 81.8%~100.0%. The method offered high selectivity, sensitivity, and gave a satisfactory results for real sample analysis.

Technical Notes

Select

Determination of five biogenic amines in source water by ion chromatography ZHAO Xinying, JIAO Xia, XIA Min, LIU Qing, ZHANG Jinghua 2009, 27 (4):  505-508.  Abstract ( 2703 )   [Full Text(HTML)] () PDF (173KB) ( 934 )   An ion chromatographic (IC) method was developed for the separation of five biogenic amines (BAs), including putrescine, cadaverine, histamine, spermidine and spermine, in source water. The sample was separated on a TSK-GEL SuperIC cation exchange column (150 mm×4.6 mm) after filtering treatment by 0.45 μm inorganic membrane. Methanesulfonic acid was used as eluent for concentration gradient elution at the rate of 1.0 mL/min. The injection volume was 100 μL and the BAs were detected by a non-suppressed conductivity detector. The result showed that the baseline separation was obtained for the 5 kinds of BAs. The linear relationships between the concentration and the peak area were obtained in the concentration range of 1.0~30.0 mg/L. The relative standard deviations (RSDs) of retention time and peak area were no more than 0.02% and 2.08%, respectively. The recoveries were from 96.0% to 107.0%. The method is simple, rapid, highly sensitive and with good repeatability. It could be used for the determination the BAs in the source water.

Select

Isolation and determination of Neoechinulin A in Cordate Pinellia Tuber WANG Qi, ZHAO Yunli, GAO Xiaoxia, WANG Xinyang, YU Zhiguo 2009, 27 (4):  509-512.  Abstract ( 3228 )   [Full Text(HTML)] () PDF (4676KB) ( 648 )   The Neoechinulin A in Cordate Pinellia Tuber was isolated by column chromatography and identified by mass spectrometry and nuclear magnetic resonance (NMR). A method of reversed-phase high performance liquid chromatography (RP-HPLC) for the determination of the Neoechinulin A in Cordate Pinellia Tuber was developed. The chromatography was performed on a Diamonsil C18 column (250 mm×4.6 mm, 5 μm) with a mixture of methanol and 0.1% phosphoric acid solution (63:37, v/v) as mobile phase at a flow rate of 1.0 mL/min. The detection wavelength was set at 225 nm and the column oven temperature was set at 30 ℃. The volume of injection was 10 μL. There was a good linear relationship (r0.9995) between the mass concentration and the peak area of Neoechinulin A in the range of 2.0~40.0 mg/L. The recovery was 98.3%~101.1%. The method is rapid and simple with good accuracy, reproducibility and suitable for the quality control of Cordate Pinellia Tuber from different sources.

Select

Rapid determination of melamine in eggs by high performance liquid chromatography TANG Tao, LI Shuanghua, LIU Fan, YU Shuxin, LI Tong 2009, 27 (4):  513-515.  Abstract ( 2466 )   [Full Text(HTML)] () PDF (174KB) ( 642 )   A rapid method for the determination of melamine in eggs was established using high performance liquid chromatography (HPLC). The melamine in a test sample was extracted with ultrasonic in 1% trichloroacetic acid for 10 min, and then purified with precipitation, centrifugation and filtration, at last tested by HPLC system. The total time of HPLC analysis for each sample was only 10 min. The linear range was from 0.05 to 20.0 mg/L as the linear correlation coefficient was 0.9999. The limit of quantification was 0.10 mg/kg (S/N＞10). The average recoveries were between 94.2% and 107% in the spiked range of 1.0~6.0 mg/kg in eggs. The relative standard deviations (RSDs) of parallel determination were between 1.53% and 2.06%(n6). This method is simple, fast, sensitive and suitable for the determination of melamine in eggs.