离子排斥色谱法同时测定生物质液体燃料发酵液中的有机酸、糖、醇

建立了离子排斥色谱法同时分析生物质燃料乙醇发酵液中糖、酸和醇的方法。使用Bio-Rad Aminex HPX–87H离子排斥色谱柱,以5 mmol/L H2SO4为流动相,柱温为65℃,流量为0.6 m L/min,用示差折光检测器对玉米秸秆发酵液中的纤维二糖、葡萄糖、木糖、阿拉伯糖、甲酸、乙酸、丁酸、乙醇进行定量分析。方法的加标回收率为97.5%~107.4%,相对标准偏差为0.27%~2.19%(n=6),线性相关系数均大于0.999。该方法适用于生物质发酵制乙醇过程中发酵糖、有机酸和乙醇的测定。     

Solid-Phase Extraction and High-Performance Liquid Chromatography for Simultaneous Determination of Important Bioactive Ginsenosides in Pharmaceutical Preparations

A robust method based on high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection has been developed for simultaneous determination of six important ginsenosides (Rg1, Re, Rb1, Rc, Rb2, and Rd) in pharmaceutical preparations. For sample preparation, simple and efficient extraction by ultrasonication, combined with solid-phase extraction (SPE) for clean-up, was effective without consuming large amounts of solvent. Chromatographic separation was performed on an ODS column with optimized gradient elution by means of a dual-solvent-pumping system. The validated method results in excellent separation, and quantitative determination is highly precise and accurate. The problem of co-elution of ginsenosides Rg1 and Re is also solved, with good resolution (R_S approx. 1.5). Intraday variation was between 0.2 and 4.4% and interday variation was between 0.4 and 6.5% (n=5 for both). The accuracy was satisfactory—in the range 93.9 to 103.4% from replicate evaluation at three different spiking concentrations. Overall limits of detection based on a typical injection volume of 5 μL were from 1.16 to 1.58 ng μL⁻¹. The validated method enabled complete assessment for quality control of ginseng samples. The technique may be performed with less sample preparation and, consequently, reduced possibility of sample loss.     

Simultaneous LC Determination of Ginsenosides Using a Modified Extraction Procedure and an Improved Step Gradient Program

A novel, accurate and precise high performance liquid chromatographic method has been developed for simultaneous determination of seven important ginsenosides (Rg1, Re, Rf, Rb1, Rc, Rb2 and Rd) in ginseng products. The separation was performed on a Shim-pack VP-ODS column (5 μm, 150 ×2 mm i.d) with ultraviolet detection at 200 nm by using the improved step gradient elution program. The LODs (S/N = 3) were in the range 0.29 to 1.33 ng μL⁻¹. All calibration curves showed a good linearity (R² > 0.998) over the ranges tested. The recoveries obtained from spiked sample were between 95.1% and 98.7%. The proposed method was successfully applied to several ginseng pharmaceutical samples. For the sample preparation, a modified extraction method was made to improve the extraction efficiency by evaluation of five solvent systems. The results demonstrated that the extraction with methanol-water (80:20, v/v) is suitable method preferably for the extraction of the ginsenosides. On leave from Department of Pharmacy and Applied Chemistry, Jilin Institute of Chemical Technology, Jilin 132022, P. R. China     

Simultaneous Determination of Various Classes of Pesticides Using Micellar Electrokinetic Capillary Chromatographyin Combination with Solid-Phase Extraction

The potential of micellar electrokinetic capillary chromatography (MEKC) with UV-detection for the simultaneous determination of various selected pesticides in water samples was investigated. The developed method using solid-phase extraction showed high efficiency and good resolution with detection limits in the 0.2 to 0.5 ppm range. Comparison of several SPE cartridges demonstrates their suitability for the extraction of pesticides with different hydrophobicity achieving 5000-fold enrichment. The described method involving SPE procedure and MEKC separation enables the successful determination of a wide spectrum of pesticides in water in the range of maximum residue limits (MRLs).     

气相色谱法测定饮料酒中的低沸点有机酸

在非质子极性溶剂-二甲基乙酰胺中,室温下用碘乙烷与C_1—C_6脂肪酸及乳酸的四甲基铵盐反应制备各酸相应的乙酯。乙酯在15%的邻苯二甲酸二壬酯与6%的土温-80混合固定液填充柱上获得满意分离。用本法测定饮料酒中的低沸点有机酸含量,简便、快速、准确。     

Method Development for the Determination of Seven Organic Acids in Wines by Reversed-Phase High Performance Liquid Chromatography

A simple high performance liquid chromatographic method is described for the determination of seven organic acids usually found in wines. The acids were eluted in the isocratic mode, in less than 12 min, on a reversed-phase ODS-2 (250 × 4 mm I.D.), 5 m, column with 0.02 M potassium dihydrogen phosphate (pH 2.88), to which was added a small amount of methanol (2%) as organic modifier, and were detected by ultraviolet absorbance at 230 nm. Galacturonic, tartaric, malic (both enantiomers), lactic, acetic, citric and succinic acids were determined, using xanthine as a chromatographic internal standard. The method was applied to white and red wines of Greek origin, after sample clean-up with polyvinylpyrrolidone, followed by passage through SAX cartridges and yielded recoveries from 78.0 to 106.8%. The limits of detection ranged between 0.001–0.05 g.L^–1 and the linear ranges between 0.003–2.0 g.L^–1.     

Determination by LC of Polyphenols in Italian Red Wine

A reversed-phase liquid chromatographic method, optimised for the separation of trans-, and cis-resveratrol, catechin, epicatechin, quercetin and rutin, is reported. Separation was achieved using a C18 column and a gradient elution with acetonitrile and 5% formic acid aqueous solution. The analyses required an equilibration period of 10 min and a run time of 25 min for completion. Identification was based on retention characteristics and by relative UV spectra, obtained by photodiode array detector and were compared with commercial standards. Analyses were performed without any sample pre-treatment. Detection was carried out by UV–Vis detector at three different wavelengths. The detection limit ranged from 0.16 μgm L⁻¹ (cis-resveratrol) to 1.5 μgm L⁻¹ (+)-catechin. Investigation was extended to quantitative determination of phenol compounds in Italian red wine and to investigate the stability of the six antioxidants.     

Solid-Phase Extraction and LC with Fluorescence Detection for Analysis of PAHs in Rainwater

The efficiency of extraction of polycyclic aromatic hydrocarbons (PAHs) from rainwater by solid-phase extraction (SPE) with three different types of cartridge, and analysis by high-performance liquid chromatography with fluorescence detection, are discussed in this paper. Three cartridges were investigated but only one was suitable. After equilibration in a desiccator for 65–80 h or in ambient air for 90–100 h the SPE cartridges were activated with 5 mL dichloromethane then 5 mL 2-propanol. The volume of sample passed through the cartridges was 50 mL; after loading of the sample the cartridges were dried under vacuum for approximately 20 min by application of a pressure of 15 mbar to the SPE manifold. The PAHs were eluted with 5 mL dichloromethane–hexane, 50:50 (v/v). The flow rate used for conditioning, sample loading, and elution was 2.5 mL min⁻¹, achieved by application of a pressure of 6 mbar. For analysis of PAHs in rainwater, recovery was between 67 and 99%, the relative standard deviation varied between 2 and 5%, and the detection limits of the method were less than 16.9 ng L⁻¹ for several PAHs. These optimum conditions were used for analysis of rainwater collected between June 2002 and May 2003 at two sites in Alsace (eastern France) and 17 PAHs were quantitatively determined. Concentrations varied between 1.6 and 968.1 ng L⁻¹.     

Validation of an Ion-Interaction Chromatography Analysis of Underivatized Amino Acids in Commercial Preparation Using Evaporative Light Scattering Detection

A liquid chromatographic procedure using ion interaction reagent and evaporative light scattering detection was developed and validated for the direct quantification of 8 underivatized amino acids (threonine, lysine, valine, methionine, isoleucine, leucine, phenylalanine and tryptophan) present simultaneously in a commercial preparation. The chromatographic separation was achieved on a Purospher RP-18e column with an acetonitrile gradient and using heptafluorobutyric acid as volatile ion interaction reagent. Acceptable levels of linearity, specificity, precision, accuracy, robustness and limits of detection were achieved during the validation of the method. Detection limits varied from 1 mg.L^–1 to 2 mg.L^–1 depending on the amino acid being analyzed. The results of this method agree to within 98.6%–102.5% when compared to the manufacturers certificate of analysis obtained with the standard amino acid autoanalyser method. This approach yields a simple, universal method that is well suited for amino acid analysis, when a sufficient quantity is available. Only basic LC instrumentation with an ELSD is necessary for this procedure.     

纤维素水解液厌氧发酵产丁二酸发酵液中有机酸和混合单糖的测定

对于以纤维素类原料(玉米皮)水解糖液作碳源厌氧发酵制备丁二酸的发酵液,利用Aminex HPX-87H(300 mm×7 8 mm i.d., 5 μm)离子排斥色谱柱及折光示差检测器检测,以0 005 mol/L H2SO4溶液(pH 2 0)作流动相,在流速为0 6 mL/min,柱温为55 ℃时对发酵液进行检测,16 min内能将发酵液中甲酸、乙酸、丁二酸、葡萄糖、木糖、阿拉伯糖完全分离定量.6种物质线性相关系数均大于0 999,方法的回收率为99 3%～102 1%;RSD为0 6%～1 6%.本方法能够简便、快速测定丁二酸发酵体系中有机酸及单糖的含量.     

Simplified Solid-Phase Extraction Procedure and Liquid Chromatographic Determination of Celecoxib in Rat Serum

A simplified solid phase extraction method, eliminating a preliminary protein precipitation has been developed for the determination of celecoxib in rat plasma. The technique included a solid phase extraction of the serum samples on a [poly (divinylbenzene-co-N-vinylpyrrolidone)] sorbent. After conditioning, the cartridge was loaded with 0.5 mL of acidified serum containing internal standard. Elution was made with 1 mL of a mixture of acetonitrile and methanol (1/1, v/v). After evaporation of the eluate to dryness and reconstitution with methanol, the samples were analyzed on an octadecyl bonded phase with several mobile phases containing acetonitrile and a phosphate buffer. Detection was carried out using a Photodiode Array Detector. Full validation of the proposed method was provided (linearity range: 0.01–2 mg. L^–1, average extraction efficiency: 92.4%; average intra-day variability: 4.6% with an accuracy of 94.8%; average interday variability: 5% with an accuracy of 95.3%, limit of detection: 0.005 mg. L^–1, limit of quantification: 0.002 mg. L^–1). The proposed method was successfully utilised to quantify celecoxib in rat plasma for a pharmacokinetic study.Revised: 26 January and 23 April 2004     

固相萃取-高效液相色谱法测定水中BPA、NP和OP含量

采用国产新型D4020大孔吸附树脂自制固相萃取柱,研究了柱长、上样速度、样品溶液的pH、盐浓度等因素对壬基酚、辛基酚和双酚A吸附率的影响,确定了最佳固相萃取条件,建立了固相萃取-高效液相色谱测定水中痕量壬基酚、辛基酚和双酚A的分析方法.该法双酚A、壬基酚和辛基酚的检出限分别为0.432 μg/L、0.998 μg/L和1.336 μg/L,回收率为91%～96%,相对标准偏差(RSD)为1.5%～5.6%.方法简便快速、成本低廉,灵敏度高,准确度好,用于实际水样分析,取得满意结果.     

Simultaneous Determination of Organic Acids in Wine Samples by Capillary Electrophoresis and UV Detection: Optimization with Five Different Background Electrolytes

A simple technique is described for the routine capillary electrophoretic determination of organic acids in wine samples. Several aromatic and non‐aromatic compounds, including phthalic acid, benzoic acid, sorbic acid, boric acid, and phosphate, were evaluated as background electrolytes in order to obtain the highest resolution and detection sensivity. Factors that affect capillary electrophoretic separation such as the concentration and pH of the background electrolyte (BGE), the concentration of the electroosmotic flow modifier (EOF), and methanol addition to the electrolyte were investigated systematically. Tartaric, malic, succinic, acetic, and lactic acids were determined simultaneously in approximately six minutes using an electrolyte containing 3 mM phosphate and 0.5 mM myristyltrimethylammonium bromide (MTAB) as electroosmotic flow modifier at pH 6.5. This method is quantitative, with recoveries in the 90–102% range and linear up to 50 mg L^–1. The precision is better than 1% and the procedure shows the appropriate sensibility, with detection limits between 0.015 and 0.054 mg L^–1. The proposed method was successfully employed for the determination of organic acids in wine samples by direct sample injection after appropriate dilution and filtration.     

固相萃取高效液相色谱法分析酱油中的有机酸

用ＰＴ－Ｃ１８预１８预处理小柱进行样品的前处理,以μＢｏｎｄａｐａｋ Ｃ１８为分析,磷酸盐缓冲液作流动相,紫外２１４ｎｍ检测,建立了酱油中多种有机酸的高效液相色谱分析方法,回收率９６％－１１３％。     

High-Performance Liquid Chromatographic Assay of Zonisamide (1,2-benzisoxazole-3-methanesulfonamide) in Human Plasma using a Solid-Phase Extraction Technique

A selective and sensitive liquid chromatographic method was developed for the determination of zonisamide in small volumes of plasma. Zonisamide and the internal standard methyl 4-hydroxybenzoate were extracted from 0.2 mL of plasma with solid-phase extraction columns and eluted with methanol. Analysis of the extracts was performed on a Symmetry C₁₈ column with ultra-violet spectrophotometric detection. The calibration curve was linear over the concentration range of 0.05–5 g mL^–1 in plasma. Recoveries were reasonable for routine analyses; the limit of quantification was 0.05 g mL^–1 with a signal-to-noise ratio of 5. This method could be useful for the pharmacokinetic study of zonisamide in a limited volume of human plasma and for therapeutic drug monitoring.     

Solid-Phase Extraction/High-Performance Liquid Chromatography-Electrospray Mass Spectrometry to Determine Endocrine Disruptors in Water Samples

A method for determining a group of endocrine-disrupting compounds in water samples was developed. This method was based on high-performance liquid chromatography-(electrospray) mass spectrometry (HPLC-(ESI)MS), working in negative ionization (NI) mode. Solid-phase extraction (SPE) with 200 mg Lichrolut EN was used to preconcentrate the water samples. The performance of the method was tested with several environmental water samples such as river, marine and influent and effluent water from a sewage treatment plant (STP). The limits of detection (LODs) of the method were between 0.001 and 0.3 g L^–1 under selective-ion monitoring (SIM) acquisition mode for 500 mL of river, marine and STP effluent water samples and between 0.01 and 3 g L^–1 for 100 mL of STP influent water. We determined some endocrine disruptors, such as diuron, bisphenol A (BPA), estrone, 4-tert-butylphenol (4-t-BP), 4-tert-octylphenol (4-t-OP) and pentachlorophenol (PCP), in several water samples at levels of g L^–1.     

Determination of biogenic amines in wine after clean-up by solid-phase extraction

Summary A suitable method for the determination of 16 biogenic amines in wine has been developed. The method involves clean-up of wine samples using ion-exchange cartridges and a preconcentration step, under controlled vacuum, before derivatization of the amines by treatment with phthalaldehyde (PA) and reversedphase HPLC with gradient elution and fluorimetric detection. Linearity of response was obtained for all the biogenic amines from 100 g L^–1 to mg L^–1. Limits of detection for the amines were similar for all PA-derivatives (25–50 g L^–1) and the quantitation limits were about 0.1 mg L^–1. After clean-up and preconcentration, the concentration levels increased 10-fold for all amines except putrescine and cadaverine, which gave poor recovery by this method unlike the rest which gave recoveries of almost 90%. The overall process was successfully applied to identify and quantify biogenic amines in several red wines from the Tarragona region.     

Simultaneous Determination of Inorganic Anions and Organic Acids in Environmental Samples by Capillary Zone Electrophoresis with Indirect UV Detection

Capillary zone electrophoresis (CZE) with indirect UV detection was developed for the simultaneous determination of inorganic anions and organic acids in environmental samples. Various aromatic acids (benzoic, phthalic, trimellitic, and pyromellitic acids) were evaluated as background electrolytes (BGEs) to give high resolution and detection sensitivity. Co-electroosmotic conditions such as the concentration of BGE, electrolyte pH, and EOF modifier were systematically investigated. Three inorganic anions and ten organic acids were determined simultaneously in 10 min using an electrolyte containing 10 mM phthalic acid, 0.5 mM myristyltrimethylammonium bromide (MTAB), and 5% methanol (MeOH) (v/v) at pH 5.60. Linear plots for the test solutes were obtained in the concentration range 0.01–1.0 mM with detection limits in the range 5–30 μM. The proposed method was successfully demonstrated for the determination of inorganic anions and organic acids in natural water, soil, and plant extracts after direct sample injection.     

Determination of Biodiesel and Triacylglycerols in Diesel Fuel by LC

A high performance liquid chromatographic method was developed for quantifying blends of biodiesel (simple alkyl esters of fatty acids) in petrodiesel. The method uses a silica column with an isocratic mobile phase consisting of hexane and methyl t-butyl ether. Separated components were quantitated using either an evaporative light scattering detector (ELSD) or UV detector. Precision of injection and linearity of response of the ELSD and UV detectors over a range of biodiesel-petrodiesel blends [1–30 v/v %] were established by use of standards. The method also can be used for quantitating similar levels of oils or fats (triacylglycerols) in petrodiesel.     

Simultaneous Determination of Cyanazine, Chlorotoluron and Chlorbenzuron in Environmental Water Samples with SPE Multiwalled Carbon Nanotubes and LC

In this paper, a new method based on solid-phase extraction with multiwalled carbon nanotubes as the packed materials for sensitive determination of cyanazine, chlorotoluron and chlorbenzuron in environmental water samples was demonstrated. Related parameters that may influence the enrichment efficiency of multiwalled carbon nanotubes such as the kind and volume of elute, sample flow rate, sample pH, and volume of the water samples were investigated. Under the optimum conditions, the detection limits of cyanazine, chlorbenzuron and chlorotoluron were 0.015, 0.012, 0.034 ng mL⁻¹, respectively. The experimental results indicated a good linearity (R ² > 0.9947) over the concentration range of 0.4–40 ng mL⁻¹ for cyanazine and chlorotoluron, and 0.8–80 ng mL⁻¹ for chlorbenzuron. The relative standard deviations of the three analytes were 3.54, 1.55 and 1.38%, respectively. The established method also was applied to the analysis of the real-world water samples and excellent achievements were obtained with average spiked recoveries from 87.8 to 110.1%. All the results indicated that this procedure could allow the simultaneous determination of these three compounds in environmental water samples at trace levels.