气相色谱直接进样法分析环已烷氧化废液中的有机酸

环已烷氧化放心液经酸化、抽滤等预处理后，采用气相色谱直接进样法分离了样品中的10种有机酸，并测定了其含量。测定废液中各有机酸的回收率在95%-105%之间。气相色谱固定的相为5%新戊二醇已二酸酯 0.2%磷酸/101酸洗白色担体。     

气相色谱法测定环己烷中甲酸

提出了测定环己烷中甲酸含量的气相色谱法,采用热导池检测器,癸二酸/GDX103不锈钢填充柱(2m×2mm),优化了色谱条件,测得检出限(3S/N)为11 0 mg·kg-1,甲酸的质量浓度在10.0～100.0 g·L-1范围呈线性关系,测得加标回收率在96.0%～104.3%之间,对20.0,100.0 g.L-1甲酸标准测定7次,相对标准偏差分别为3.2%和1.9%,符合环己烷工艺中甲酸含量测定的技术要求.     

用于环己烷氧化混合产物的分析方法

针对环己烷空气液相氧化混合产物的不同特性，采用了不同的测定方法：环己基过氧化氢采用间接碘量法定量；酸和酯采用酸碱滴定法定量；环己醇和环己酮等有机物采用气相色谱法，但进样前先加入三苯基膦以避免环己基过氧化氢的干扰。该方法回收率为96．62％～101．69％，相对标准偏差为1．12％～5．09％。     

气相色谱-质谱法分析山楂果中的有机酸

山楂(Hawthorn),别名红果,蔷薇科山楂属(Crataegus)植物,山楂果营养丰富,是最早被列入食药兼用的水果之一,具有消食化滞,行气散瘀等功效。山楂果中起消食导滞作用的有效成分是有机酸。本文对文献的实验条件进行合理改进,用GC—MS法对河南辉县和桐柏山两地山楂果中有机酸成分进行了系统分析,各有机酸成分得到有效分离;并利用选择离子方法测定了其中8种主要有机酸的含量,以期对山楂果的食用、药用价值以及开发研制功能性保健食品提供科学依据。     

药厂废液中有机酸的分离分析

利用减压蒸溜法分离废液中的低沸点有机酸,结合红外光谱、气相色谱、质谱,确定了废液中以乙酸、丙酸为主的10种有机酸的结构,其含量占分析废液的2.64%。其中丙酸含量最高,其次为乙酸。同时被检测到的还有乙醇,乙醛等。另外通过柱层析分离高级脂肪酸,并进行衍生化处理,经GC、GC-MS检测,确定了四种高沸点有机酸的结构,含量为1.71%。9,12-十八二烯酸含量相对较高。因此有机酸占废液总量的质量分数为4.35%。     

气相色谱法直接进样测定工业废气中的苯乙烯

建立了直接进样测定工业废气中苯乙烯的气相色谱法.工业废气样品通过气体进样阀进入气相色谱仪中进行分离和检测,采用0.25 mL气体进样阀时,方法的检出限为1.4 mg/m3,苯乙烯含量在3.19～51.0 mg/m3时,测定结果的相对标准偏差为2.19％～4.50％(n=5),与行业标准HJ 583-2010,HJ 584-2010相比,该方法操作简便、快速,适合工业废气中苯乙烯的快速测定.     

羊水中有机酸类代谢物的气相色谱-质谱研究

有机酸遗传代谢病是一类由于单基因或多基因变化导致的代谢障碍疾病。基因的变化通常表达为相应酶的缺失,严重影响人的智力发育。据watts等人的观察,1788例临床痴呆病患者中约有5％是因有机酸遗传代谢病造成的。虽然它的发病率不高,但由于目前对此病还缺乏有效的治疗方法,因而     

直接进样气相色谱法分析有机芳香酸

用实验室合成的十二烷基苯磺酸甲铵配成固定液溶液,以汞塞动态法制备成毛细管色谱柱。讨论了该毛细管柱的制备方法,对有机芳香酸的分离以及定量分析问题。     

Gas chromatographic determination of 29 organic acids in foodstuffs after continuous solid-phase extraction

A simple and expeditious method based on continuous solid-phase extraction and gas chromatography-mass spectrometry (GC-MS) was reported for the direct determination of 29 organic acids in food and beverages. A sorbent column packed with 80 mg of LiChrolut EN-Supelclean ENVI-18 (1:1) was employed for extraction and clean-up purposes. After elution with 200 μL of methanol, the methanolic extract was directly injected into the GC-MS without prior derivatization. The method provided good linearity (0.5-1000 μg kg⁻¹) and fairly good precision for all compounds (RSD lower than 6.2%). The recoveries of the organic acids from diluted samples that were spiked at three different concentrations (10, 40 and 100 μg kg⁻¹) ranged from 93 to 98%. The applicability of the method was demonstrated by analyzing the target compounds in a wide variety of foodstuffs including beer, wine, fruit juice, soy sauce, soya milk and honey samples.     

Gas chromatographic analysis of organic solvent mixtures on capillary columns of different polarity

Summary A gas chromatographic method for the analysis of organic solvents in chemical products is described. The analysis is performed by the use of a polar column, Supelcowax 10, and a non-polar column CP-Sil-5CB. Samples containing a non-volatile matrix or water were analysed by headspace analysis. The identification of the solvents in a sample, based on GC retention times on one column, is confirmed by GC of the sample on the second column. The method has been found to be suitable for the routine analysis of solvent mixtures.     

A fast derivatization procedure for gas chromatographic analysis of perfluorinated organic acids

A rapid and simple derivatization procedure has been developed for gas chromatographic determination of perfluorinated organic acids (PFCAs, C₆–C₁₂), using isobutyl chloroformate (IBCF) to convert the acids into the more volatile isobutyl esters, under catalysis by pyridine. The procedure was optimized in an acetonitrile medium and applied to GC techniques with electron-capture detection (GC-ECD) and mass spectrometry with electron-impact ionization (GC-EI-MS); for the sake of comparison, HPLC with electrospray-ionization MS (HPLC-ESI(−)-MS) was also tested. The LOD and LOQ values obtained for these three techniques were compared, and the lowest LODs were obtained with GC-ECD (0.06–1.80 μg mL⁻¹). The procedure was further optimized in an aqueous medium, obtaining the best results in a phosphate buffer (pH 2.5, 50 mmol L⁻¹), in which the LOD and LOQ values were measured for GC-ECD a GC-EI-MS. The lowest LODs were found for GC-EI-MS (0.030–0.314 μg mL⁻¹). The practical applicability was tested on Vltava river water samples.     

Recovery of organic acids from waste salt solutions derived from the manufacture of cyclohexanone by electrodialysis

The possibility of recovery of organic acids from waste salt solution, derived from the manufacture of cyclohexanone, by means of single anion-exchange membrane electrodialysis was studied in this paper. Some key parameters, such as voltage, current density, pH value, current efficiency and specific energy consumption are studied and analyzed in details on theoretical basis. Results indicate that single anion-exchange membrane electrodialysis is found to be a feasible method for recovery of organic acids. Several valuable acids, such as butyric and adipic acids are effectively separated from waste salt solution by only one-step electrodialysis. And it consumes less energy compared to the conventional processes.     

High-performance liquid chromatographic determination of major organic acids in apple juices and ciders

Summary A reversed-phase high-pressure liquid chromatographic method is presented for the simultaneous separation and determination of malic, citric, lactic, succinic and ascorbic acids in apple juices and ciders. After filtration and/or degasification, the organic acids in the sample are separated on a LiChrosorb/C₁₈ column and quantified by using a rapid diode array detector. The method is considered to be a suitable choice for the accurate and precise determination (C.V. 5%) of these compounds.     

Gas chromatographic method for determining free fatty acids in cheese

Summary A rapid gas chromatographic method for the analysis of individual free fatty acids (FFA) in cheese has been developed. Lipds were extract from a cheese paste acidified with diethyl ether and tetramethylammonium hydroxide (TMAM) was used for converting the FFA to TMA-soaps, which are transformed to methyl esters in the chromatographic injector. The effect of lactic acid was determined. The reproducibility of the method was studied and the coefficient of variation for the total FFA was found to be 2.2%. Recovery of individual FFA was in the range 87 to 106%.     

Direct sample injection for capillary electrophoretic determination of organic acids in cerebrospinal fluid

Organic acids in cerebrospinal fluid (CSF) are potential diagnostic markers for neurological diseases and metabolic disorders. A capillary electrophoretic (CE) method for the direct analysis, i.e., without any sample preparation, of six organic acids in CSF was developed. A capillary coating consisting of a triple layer of charged polymers (polybrene-dextran sulfate-polybrene) was used in combination with a negative separation voltage, providing fast and efficient analysis of acidic compounds. Separation conditions, such as background electrolyte (BGE) concentration and pH were optimized, and the influence of albumin and sodium chloride was systematically studied using a set of test compounds. With injection volumes of ca. 44 nL, plate numbers of up to ca. 150,000 were obtained with a BGE of 200 mM sodium phosphate (pH 6.0). It appeared that high sodium chloride concentrations in the sample hardly affected the peak width and shape of the organic acids, most probably due to transient isotachophoresis effects occurring in the sample zone. Adverse effects of CSF proteins, which frequently compromise the CE performance, could be effectively minimized by the triple layer coating in combination with rinses of 0.1 M hydrochloric acid. Overall, the developed CE system allowed direct injections of CSF samples, yielding good separation efficiencies and stable migration times (RSDs < 2%) for organic acids. Validation of the method with artificial and real CSF samples showed good linear responses (r > 0.99), and LODs for the organic acids were in the range of 2–8 μg/mL when applying UV detection. RSDs for migration times and peak areas were <2% and <7%, respectively. The applicability of the CE system is shown for the determination of organic acids in CSF samples.     

Ion chromatographic determination of some organic acids, chloride and phosphate in coffee and tea

An ion chromatographic method for the simultaneous determination of organic acids and inorganic ions is described. Acetic, malic, ascorbic, citric, malic and succinic acids, chloride and phosphate were determined in coffee and tea samples. The separation is performed on an anion-exchange column operated at 40 °C within 25 min by an isocratic elution with 0.6 mM aqueous potassium hydrogenphthalate (pH 4.0) solution containing 4% (v/v) acetonitrile as eluent and determination by conductivity detection. The method does not need a special sample treatment and was successfully applied to the analysis of black, green and oolong tea samples. Also, green and roasted coffee samples from the varieties arabica and robusta were analyzed.     

气相色谱法测定柴胡注射液中环己醇

建立了气相色谱法测定柴胡注射液中环己醇的定量分析方法，以正己烷为萃取剂，水蒸汽蒸馏浓缩富集提取液，用PEG－20M柱，氢火焰检测器（FID）检测。结果表明，柴胡注射液中环己醇质量浓度在10.0μg/mL-120.0μg/mL范围内呈良好的线性关系（r=0.998），回收率为92 .3%-95.1%，RSD为1.1%－1.2%。