Ion chromatographic determination of organic acids in food samples using a permanent coating graphite carbon column

From the viewpoint of a graphite carbon column with excellent durability, it was applied to the ion chromatography (IC) of several organic acids. The carbon column was permanently coated with the cetyltrimethylammonium (CTMA) ion, and the elution behaviors of several organic acids (acetic acid, lactic acid, succinic acid, malic acid, tartaric acid, citric acid) and inorganic anions (Cl⁻, NO₂⁻, NO₃⁻, SO₄²⁻) were examined according to a non-suppressed IC coupled with conductivity detector, when an ion-exchange ability was given to the graphite carbon column. When salicylic acid and sodium salicylate were used as a mobile phase, each organic acid are analyzed approximately 10 min. But the separation of malic acid, chloride and nitrite was difficult. When benzoic acid and 2-amino-2-hydroxymethyl-1,3-puropanediol (tris aminomethane) were used as a mobile phase, tartaric acid and citric acid, etc. with large valency showed tendency to which the width of each peaks extended and retention time increased. However, it was possible to separate excellently for the analytes detected within 10 min. The developed method was then applied to the determination of organic acids in several food samples.     

Determination of organic acids in alcoholic and nonalcoholic beverages by reversed-phase high-performance liquid chromatography

A procedure for the quantification of 9 organic acids, acetic, formic, citric, tartaric, lactic, malic, succinic, oxalic, and fumaric, in alcoholic and alcohol-free beverages by reversed-phase HPLC on a Pronto-SIL C18 AQ (300 × 3 mm) column (3 μm) with the mobile phase 5 mM Li₂SO₄ (pH 3.00, H₂SO₄) at the rate 0.5 mL/min and conductometry detection. The analytical ranges made 5–200 mg/L for tartaric, malic, lactic and acetic acids, 2–200 mg/L for the citric and fumaric, 10–400 mg/L for succinic, 15–400 for oxalic, and 20–200 for the formic acids, and so the detection limits: 1 mg/L for tartaric, formic, malic and fumaric, 2 mg/L for lactic, acetic and citric, 5 mg/L for succinic, and 10 mg/L for oxalic acids. The analysis of alcoholic beverages takes 30–40 min, and of non-alcoholic ones, 20–30 min; the standard deviation of the results of analyses does not exceed 5%.     

HPLC analysis of organic acids using a novel stationary phase

In the present work, a high performance liquid chromatographic method with UV detection for the separation of six organic acids including, tartaric, malic, acetic, lactic, citric and succinic is described.The separation was performed on a novel stationary phase TEKNOKROMA, Tr-010065 Mediterranea sea₁₈ (15 cm × 0.4 cm, i.d. 3 μm) and using water with a 0.1% (v/v) of formic acid as mobile phase. The advantages of this packing over a conventional octadecylsilane (ODS2) column are reported.The method was validated with respect to linearity, limits of detection and repeatabilities within day and between days and satisfactory results were obtained.The proposed method was applied for the determination of these compounds in commercially available white wines. The samples were injected directly without previous treatment. LC-MS was used as a confirmatory technique.     

Electrochemical behaviour of isatin at a glassy carbon electrode

A rapid, reliable and simple capillary zone electrophoresis method for the determination of organic acids in beverages was developed. The complete separation of oxalic, formic, tartaric, malic, succinic, maleic, glutaric, pyruvic, acetic, lactic, citric, butyric, benzoic, sorbic, ascorbic and gluconic acids can be achieved in less than 3.5 min with a simple electrolyte composed by phosphate as the carrier buffer (7.5 mM NaH₂PO₄ and 2.5 mM Na₂HPO₄), 2.5 mM TTAOH as electroosmotic flow modifier and 0.24 mM CaCl₂ as selectivity modifier, adjusting the pH at 6.40 constant value. Injection was performed in hydrodynamic mode (30 s) and the detection mode was UV direct at 185 nm. The running voltage was −25 kV at thermostated temperature of 25 °C. The method developed has been applied to several beverage samples with only a simple dilution and filtration treatment of the sample. The proposed method is fast because the separation time decrease two, four or, even, six times the separation times of the previous reported CZE methods. It is also simple and cheap due to a low consumption of chemicals and samples. These reasons permit it to be considered adequate for routine analysis of organic acids in beverage samples.     

高效液相色谱法测定铬超富集植物李氏禾根系分泌物中的有机酸

建立了高效液相色谱（HPLC）测定Cr超富集植物李氏禾根系分泌物中低相对分子质量有机酸的分析方法。采用XSelect HSS T3色谱柱（250 mm×4.6 mm,5 μm,Waters）,以40 mmol/L磷酸二氢钾-磷酸缓冲溶液（pH=2.40）作流动相,流速1.0 mL/min,柱温25℃,在波长205 nm处检测。该方法在13 min内简便快速地分离出8种有机酸（草酸、酒石酸、苹果酸、乳酸、甲酸、乙酸、马来酸和柠檬酸）,且峰形良好。有机酸的检出限（LOD）为0.12~12.32 mg/L;草酸的加标回收率为73.15%,其他有机酸的加标回收率为94.54%~109.98%。李氏禾的根系分泌物中各有机酸含量分别为酒石酸（130.90±1.44）μg/g（根干重）、苹果酸（1031.34±4.38）μg/g（根干重）、乳酸（65.54±1.01）μg/g（根干重）、马来酸（0.96000±0.00367）μg/g（根干重）和柠檬酸（201.50±1.13）μg/g（根干重）。该方法简便快速,灵敏可靠,适用于植物根系分泌物样品中有机酸的测定。     

An optimized direct method for the determination of carboxylic acids in beverages by HPLC

Summary A direct method for the simultaneous determination of tartaric, malic, lactic, acetic, citric, shikimic, fumaric and succinic acids in fruit juices and wines by isocratic reversed phase HPLC is reported.The variables (pH, ionic strength, flow and temperature) have been optimized by a modification of the original simplex method. The separation factor (s) and calibrated resolution product (r^*) have been used as criteria for selectivity optimization. After validation, the method has been applied to the determination of carboxylic acids in apple, orange and lemon juices, white and red wines and musts during the fermenation process.     

Application of HPLC to characterization and control of individual acids in apple extracts and ciders

Summary Three HPLC methods have been tested in order to compare their separation of apple and cider organic acids. Optimum results for simultaneous determination of malic, citric, quinic, succinic, lactic and shikimic acids have been obtained using an RP-18 column with phosphate buffer as the mobile phase.This method was applied to organic acids monitoring during the ripening of apples and throughout the fermentation process. After filtration and degasification the organic acids in the sample were separated, and quantified by using a diode array detector.Recovery studies show good results for all solutes (88%–106%). The coefficients of variation show excellent precision (5%).     

LC Determination of Trace Short-Chain Organic Acids in Wheat Root Exudates Under Aluminum Stress

A novel and reliable high-performance liquid chromatographic method for trace short-chain organic acids measurement in wheat root exudates under aluminum stress has been optimized and validated. The chromatographic separation of the short-chain organic acids (citric, oxalic, malonic, succinic, tartaric, malic, and acetic acids) was achieved with Bio-rad Aminex HPX-87H cation exchange resin column. These seven organic acids were identified and quantified in 25 min. Well-shaped peaks were obtained for trace organic acids using dilute sulfuric acid as mobile phase. Under optimum conditions, Bio-rad Aminex HPX-87H column showed distinct advantages of the ability to well separate different short-chain organic acids (especially for tartaric and malic acids, as well as malonic and acetic acids) in wheat root exudates under aluminum stress, and offered accurate and precise results for the analysis of these organic acids. This HPLC method can efficiently eliminate the aluminum’s interference and is quite suitable to the trace detection of trace organic acids in wheat root exudates under aluminum stress.

     

LC Determination of Trace Short-Chain Organic Acids in Wheat Root Exudates Under Aluminum Stress

A novel and reliable high-performance liquid chromatographic method for trace short-chain organic acids measurement in wheat root exudates under aluminum stress has been optimized and validated. The chromatographic separation of the short-chain organic acids (citric, oxalic, malonic, succinic, tartaric, malic, and acetic acids) was achieved with Bio-rad Aminex HPX-87H cation exchange resin column. These seven organic acids were identified and quantified in 25 min. Well-shaped peaks were obtained for trace organic acids using dilute sulfuric acid as mobile phase. Under optimum conditions, Bio-rad Aminex HPX-87H column showed distinct advantages of the ability to well separate different short-chain organic acids (especially for tartaric and malic acids, as well as malonic and acetic acids) in wheat root exudates under aluminum stress, and offered accurate and precise results for the analysis of these organic acids. This HPLC method can efficiently eliminate the aluminum’s interference and is quite suitable to the trace detection of trace organic acids in wheat root exudates under aluminum stress.     

Determination of ten organic acids by low pressure liquid chromatography

Summary Organic acids, such as lactic, malic and citric acids, are involved in primary metabolism of all living organisms. Their presence in food products contributes to the flavour and their equilibrium with inorganic cations defines to a large extent the acidity of the food preparations. A resin cation-exchanger device, normally used for separating amino-acids, can be adapted for characterizing 10 organic acids: formic, propionic, fumaric, succinic, lactic, malic tartaric, citric, and oxalic. Two monitoring systems were used, one of them based on specific iron III salt coloration with hydroxy-acids.     

Reversed phase liquid chromatographic determination of organic acids using on-line complexation with copper(II) ion

We describe a simple and sensitive liquid chromatographic method for the analysis of organic acids using on-line complexation with copper(II) ion. Organic acids complexed with copper(II) ion were separated on a reversed-phase C18 column and detected by UV absorption at 240 nm. The copper(II) ion concentration in the mobile phase had a great influence on separation and sensitivity. A mobile phase consisting of 10 mM copper(II) sulfate in 5 mM sulfuric acid (pH 2.3) was used to separate nine organic acids (tartaric, malic, malonic, lactic, acetic, citric, maleic, succinic and fumaric acids). The detection limits of the examined organic acids calculated at S/N = 3 ranged from 0.6 to 100 μM. The detector signal was linear over three orders of magnitude of organic acid concentration. The method successfully measured organic acids in juice and vinegar samples.     

Polymeric sensors for determination of anions of organic acids

New polymeric electrochemical sensors based on various neutral and charged organic ionophores were suggested. The new sensors have a high sensitivity to anions of various organic acids (acetic, oxalic, lactic, malic, succinic, tartaric, and citric) in a wide concentration range. The selectivity and the detection limit of the developed sensors with respect to anions of the acids were studied.     

Simultaneous determination of some food additives in soft drinks and other liquid foods by flow injection on-line dialysis coupled to high performance liquid chromatography

Flow injection on-line dialysis was developed for sample pretreatment prior to the simultaneous determination of some food additives by high performance liquid chromatography (FID-HPLC). A liquid sample or mixed standard solution (900 μL) was injected into a donor stream (5%, w/v, sucrose) of FID system and was pushed further through a dialysis cell, while an acceptor solution (0.025 mol L⁻¹ phosphate buffer, pH 3.75) was held in the opposite side of the dialysis membrane. The dialysate was then flowed to an injection loop of the HPLC valve, where it was further injected into the HPLC system and analyzed under isocratic reverse-phase HPLC conditions and UV detection (230 nm). The order of elution of five food additives was acesulfame-K, saccharin, caffeine, benzoic acid and sorbic acid, respectively, with the analysis time of 14 min. On-line dialysis and HPLC analysis could be performed in parallel, providing sample throughput of 4.3 h⁻¹. Dialysis efficiencies of five food additives were in ranges of 5-11%. Linear calibration graphs were in ranges of 10-100 mg L⁻¹ for acesulfame-K and saccharin, 10-250 mg L⁻¹ for benzoic acid and 10-500 mg L⁻¹ for caffeine and sorbic acid. Good precisions (RSD < 5%) for all the additives were obtained. The proposed system was applied to soft drink and other liquid food samples. Acceptable percentage recoveries could be obtained by appropriate dilution of the sample before injecting into the system. The developed system has advantages of high degrees of automation for sample pretreatment, i.e., on-line sample separation and dilution and low consumption of chemicals and materials.     

浸入式三相液相微萃取-高效液相色谱法对饮料中7种有机酸的同时测定

建立了一种利用三相液相微萃取(LPME)技术进行样品前处理、高效液相色谱(HPLC)法同时测定饮料中酒石酸、甲酸、乙酸、乳酸、琥珀酸、苹果酸和柠檬酸7种低相对分子质量有机酸的分析方法.考察了萃取溶剂、搅拌速率、盐效应、萃取时间、接收相和给出相pH值等因素对萃取效率的影响.优化后的实验条件:磷酸三丁酯(TBP)为萃取剂,萃取速率为1 000 r/min,萃取时间为35 min,给出相pH为2.5,接收相pH为12.0.该方法在较宽线性范围内显示了良好的线性关系(r＞0.993 6),检出限(S/N=3)为10.4 ～54.2 μg/L,相对标准偏差小于4.8%.7种有机酸的富集倍数为13.3 ～51.4,样品的加标回收率为85% ～103%.该方法操作简单、快速,只需使用极少量的有机溶剂,具有绿色环保的特点,可用于果汁饮料、红茶饮料及基质特别复杂的牛奶饮料中低分子量有机酸的测定,为分析复杂基质样品提供了有益的参考.     

Development and optimization of a method for the analysis of low-molecular-mass organic acids in plants by capillary electrophoresis with indirect UV detection

Capillary zone electrophoresis was developed to analyze low-molecular-mass organic acids including oxalic, tartaric, formic, malic, citric, succinic, glutaric, acetic and lactic acid. The influences of some crucial parameters such as buffer concentration, pH value, surfactant concentration and separation temperature, on electrophoretic separation were investigated. Under the conditions of 15 mM phthalate containing 0.6 mM tetradecyltrimethylammonium bromide as the run buffer (pH 5.6); separation voltage -15 kV (-263.2 V/cm) and temperature 25 degrees C, a satisfactory separation of nine organic acids was accomplished within 7 min. The detection limits (S/N=3) ranged from 0.008 to 0.08 microg/ml and the quantification limits ranged from 0.01 to 0.1 microg/ml for electrokinetic injection. The method was successfully applied to analyze organic acids in different parts of Var splendens (an edible vegetable in China). The recoveries of organic acids in real samples ranged from 88 to 121%.     

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.     

Application of co-electroosmotic capillary electrophoresis for the determination of inorganic anions and carboxylic acids in soil and plant extract with direct UV detection

Summary Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determination of inorganic anions and carboxylic acids. However, there are few reports on direct UV detection of these solutes in real samples. This paper describes the use of direct UV detection of inorganic anions and organic acids in environmental samples using co-electroosmotic capillary zone electrophoresis (co-CZE) at 185 nm. The best separation and detection of the solutes was achieved using a fused silica capillary with an electrolyte containing 25 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide (TTAB) and 15% acetonitrile (v/v) at pH 6.0. Four common inorganic anions (Cl⁻, NO₂ ⁻, NO₃ ⁻ and SO₄ ²⁻) and 11 organic acids (oxalic, formic, fumaric, tartaric, malonic, malic, citric, succinic, maleic, acetic, and lactic acid), were determined simultaneously in 15 min. Linear calibration plots for the test solutes were obtained in the range 0.02–0.5 mM with detection limits ranging from 1–9 μM depending on the analyte. The proposed method was successfully used to determine inorganic anions and carboxylic acids in soil and plant tissue extracts with direct injection of the sample.     

离子排斥色谱法同时测定果汁中11种有机酸

 用离子排斥色谱法实现了对果汁中 11种有机酸 (草酸、柠檬酸、酒石酸、苹果酸、抗坏血酸、乳酸、琥珀酸、甲酸、乙酸、戊二酸、富马酸 )的分离测定。以 17mmol/L硫酸为淋洗液 ,样品在ICE ION 30 0离子排斥柱上分离后 ,用紫外检测器在 2 10nm处测定其中的有机酸。各组分质量浓度测定的相对标准偏差在 1.5 %～ 9.8% (n =10 )。     

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.     

反相HPLC测定食物中的有机酸

本文研究了反相HPLC同时测定食物中草酸、酒石酸、苹果酸、乳酸、乙酸、柠檬酸和琥珀酸的条件,提出了用C_(18)固定相、2.5%NH_4H_2PO_4(pH2.50)溶液的流动相和在200nm下紫外检测这七种有机酸的测定方法。该法简便快速、具有较高的准确度和精密度。另外,还对有机酸的分离机理作了探讨。对十种食物中的有机酸进行了定量测定。