Separation of Aliphatic and Aromatic Carboxylic Acids by Conventional and Ultra High-Performance Ion-Exclusion Chromatography

An ion-exclusion chromatography (IELC) comparison between a conventional ion-exchange column and an ultra high-performance liquid chromatography (UHPLC) dynamically surfactant modified C18 column for the separation of an aliphatic carboxylic acid and two aromatic carboxylic acids is presented. Professional software is used to optimize the conventional IELC separation conditions for acetylsalicylic acid and the hydrolysis products: salicylic acid and acetic acid. Four different variables are simultaneously optimized including H₂SO₄ concentration, pH, flow rate, and sample injection volume. Thirty different runs are suggested by the software. The resolutions and the time of each run are calculated and feed back to the software to predict the optimum conditions. Derringer’s desirability functions are used to evaluate the test conditions and those with the highest desirability value are utilized to separate acetylsalicylic acid, salicylic acid, and acetic acid. These conditions include using a 0.35 mM H₂SO₄ (pH 3.93) eluent at a flow rate of 1 mL min^?1 and an injection volume of 72 μL. To decrease the run time and improve the performance, a UHPLC C18 column is used after dynamic modification with sodium dodecyl sulfate. Using pure water as a mobile phase, a shorter analysis time and better resolution are achieved. In addition, the elution order is different from the IELC method which indicates the contribution of the reversed-phase mode to the separation mechanism.     

Single-Run Separation and Determination of Aliphatic and Aromatic Carboxylic Acids in Wine and Human Urine Samples by Ion-Exclusion Chromatography

This work is focused on developing a new chromatographic method with UV detection for the separation and determination of thirty-two carboxylic aliphatic and/or aromatic acids in a single run. Ion-exclusion chromatography with a silica based, modified with C18, analytical column Alltech Prevail? organic acid 5 µm (150 mm × 4.6 mm I.D) was used for the solving of this problem. The developed method was based on ion-exclusion and/or hydrophobic interaction chromatographic separation mechanism. The effect of the concentrations of phosphate buffer and its pH as well as the column temperatures on the retention of the test acids has been investigated. Gradient elution of the mobile phase composed of aqueous phosphate buffer and methanol was used to achieve a required separation of carboxylic acids within 45 min. All measurements were done at 220 nm. Column temperature was set at 25 ± 0.1 °C. The LOD values for organic acids range from 0.002–2.224 mg L^?1. The repeatability of the procedure developed is characterized by the RSD, which varied between 0.52 and 2.85 % for the peak area. The proposed method was successfully applied for the determination of aliphatic and aromatic acids in dry white wine and human urine samples.     

直接电导检测离子排斥色谱法测定C1～C6脂肪族有机酸

建立了直接电导检测离子排斥色谱分离测定C1~C6脂肪族有机酸(甲酸、乙酸、丙酸、丁酸、戊酸、己酸)的方法。以Shim-pack SCR-102H 色谱柱为分离柱,选用p-甲苯磺酸水溶液为流动相,考察了流动相中p-甲苯磺酸的浓度、流速、pH、色谱柱温度对分离和测定脂肪族有机酸的影响,确定了最佳的色谱条件为：0.2 mmol/L p-甲苯磺酸水溶液作为流动相,流速1.2 mL/min,柱温45 ℃。所测有机酸的检测限为0.03～0.99 mg/L,相对标准偏差在2.3%以下(n= 5),回收率为91.2%～105.6%,整个分析过程在28 min内完成。该法用于白酒样品的分析,结果令人满意。     

Separation of Monosulfated Bile Acids by High-Performance Liquid Chromatography

Abstract

Separation of 3-, 7- and 12-monosulfates of cholate, chenodeoxycholate, deoxycholate, lithocholate and ursodeoxycholate and their glyco- and tauro-conjugates by high-performance liquid chromatography on a reversed phase column has been carried out. Effects of pH and salt concentration of a mobile phase on the k' value of sulfated bile acids were investigated with the μBondapak C₁₈ and ODS SC-02 columns. The 3-sulfated bile acids were efficiently separated on ODS SC-02 using three aqueous ammonium carbonate/acetonitrile systems. The chromatographic behaviors of 7-and 12-sulfated bile acids are also briefly discussed.     

RPLC分离果酸的研究

本文用反相高压液相色谱(RHLC)研究了果酸的分离,找到了用紫外与示差折光检测器同时检测分离果酸的最佳条件,并以0.01M(NH_4)_2HPO_4 用H_3PO_4调节PH2.2～2.5。在上述条件下使果酸得到分离,用保留时间定性,用标准酸样的直线方程来定量。并对果实橙子中的柠檬酸和健力宝饮料中的酒石酸作了定量。     

Separation and Analysis of Nucleic Acids and Their Constituents by Ion-Exclusion and Ion-Exchange Column Chromatography

The recent commercial development of high pressure liquid chromatographic instruments, and the availability of small and uniformly sized resin beads has enhanced the role of column chromatography for the rapid assay of nucleic acid components. A major advancement in the purification and analysis has been due to the recent demonstration that the ion exclusion is more or equally effective than the ion exchange as a separation principle for the resolution of purine and pyrimidine bases, nucleosides, deoxynucleosides and nucleotides^1–3. This article deals with the recent applications of separation principles that have been employed for the separation of nucleic acid constituents. The reader is referred to two review articles of Cohn for the earlier works on this subject^{4, 5}. Separations by chromatography and electrophoresis on paper and thin layers are not described here; several monographs and review articles are available in the literature^6–12.The reader is also referred to a recent methodological study for the base analysis of ribopolynucleotides by chemical tritium labeling which utilizes two dimensional chromatography on thin layers of cellulose as a separation means^{13, 14}.     

反相高效液相色谱对DABTH—氨基酸的分离与鉴定

应用反相高效液相色谱(RP-HPLC)技术,采用等度洗脱。对20种标准DABTH-氨基酸进行了分离与鉴定,灵敏度达到pmol水平;并以溶菌酶为模式蛋白,经手工DABITC/PITC双偶联方法对其N端部分序列进行Edman降解,其降解产物DABTH-氨基酸用RP-HPLC技术进行了鉴定,蛋白质微量序列分析的灵敏度达到nmol水平.     

直接电导检测-离子排斥色谱法测定芳香族羧酸

研究了直接电导检测-离子排斥色谱法分离测定芳香族羧酸(邻苯二甲酸、水杨酸、苯乙酸、对羟基苯甲酸、苯甲酸和邻甲苯甲酸)。以Shim-packSCR-102H色谱柱为分离柱,H2SO4为流动相,考察了流动相浓度、色谱柱温度、流速对分离和测定芳香族羧酸的影响,确定最佳色谱条件为:0.08mmol/LH2SO4作为流动相,柱温45℃,流速1.2mL/min。所测芳香族羧酸的检出限为0.07～0.98mg/L;相对标准偏差在2.6%以下(n=5);回收率为95.8%～100.1%。本方法用于酱油样品的分析,得到满意结果。     

Esters Derived from Vanillin and Vanillal and Aromatic and Functionalized Aliphatic Carboxylic Acids

Reactions of vanillin and vanillal with aromatic and functionally substituted aliphatic carboxylic acid chlorides in the presence of pyridine afforded the corresponding previously unknown esters.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 7, 2005, pp. 1015–1019.Original Russian Text Copyright © 2005 by Dikusar, Kozlov.     

Enantiomeric Separation of Non-Protein Amino Acids by Chiral Ligand-Exchange High-Performance Liquid Chromatography

Abstract

The enantiomeric separation by high-performance liquid chromatography of underivatized non-protein amino acids was investigated by using a column packed with octadecylsilanized silica coated with N,S-dioctyl-D-penicillamine as a chiral ligand-exchange phase (Sumichiral OA-5000). Excellent to good separations of enantiomers were achieved with a variety of nonprotein amino acids carrying aliphatic or aromatic side-chains by optimizing the amount (0-20%, v/v) of the organic component (2-propanol) and the concentration (1-5 mM) of the complexing metal ion (Cu²⁺) in the hydro-organic eluent.     

Separation and Determination of Bile Acids in Human Bile by High-Performance Liquid Chromatography

Abstract

A method for simultaneous determination of major bile acids in human bile is described. The unconjugated, glycine- and taurine-conjugated bile acids are extracted with Sep-pak C¹⁸ and separated into groups by ion-exchange chromatography on a lipophilic gel. Subsequently, resolution of each group into ursodeoxycholate, cholate, chenodeoxycholate, deoxycholate and lithocholate is attained into two stages by high-performance liquid chromatography on a Radial-PAK A column. First, 0.3% ammonium phosphate (pH 7.7)/acetonitrile (19:8, v/v) is used for separation of the latter three as a mobile phase. Ursodeoxycholate and cholate are efficiently separated in 0.3% ammonium phosphate (pH 7.7)/acetonitrile (23:8, v/v). The present method is applicable to quantitation of bile acids in human bile with satisfactory accuracy and precision.     

芳香族羧酸的高效液相色谱法测定及其在药品分析中的应用

建立了反相高效液相色谱同时测定苯甲酸、水杨酸、邻苯二甲酸、对羟基苯甲酸、对氨基苯甲酸和邻甲苯甲酸6种芳香族羧酸的方法.以ZORBAX ODS反相色谱柱为分离柱,采用紫外检测方法,研究了流动相组成、淋洗梯度和检测波长对芳香族羧酸分离效果的影响.在优化色谱条件下,即流动相为乙酸水溶液(50 mmol·L-1,pH 3.5) -甲醇(60 ∶ 40),紫外检测波长为230 nm,流速为1.0 mL·min-1,色谱柱温度为30 ℃,6种芳香族羧酸在25 min内达到基线分离.方法的检出限为0.21 ～ 0.99 mg·L-1,平均加标回收率为99.7% ～100.1%,相对标准偏差小于0.60%.将方法用于足君清酊剂和水杨酸苯甲酸松油搽剂两种药品的分析,结果满意.     

姜黄素键合硅胶固定相高效液相色谱分离取代芳香酸类化合物

研究了13种取代芳香酸类化合物在姜黄素键合硅胶固定相(CCSP)上的色谱行为,考察了甲醇含量、流动相pH值对CCSP分离取代芳香酸类化合物的影响,探讨了该固定相对芳香酸类化合物的色谱保留机理,并应用于实际样品复方水杨酸搽剂的分离分析。结果表明,在不同含量的甲醇-0.02 mol.L-1NaH2PO4(pH=2.5)流动相体系中,三组芳香酸标准混合样和实际样品中四种主要成分在CCSP上实现基线分离。与ODS柱相比,在相同条件下,CCSP对这类酸性化合物具有较高的选择性,且对13种取代芳香酸类化合物的洗脱顺序与ODS具有显著差异,其中5种溶质在CCSP上的保留强于ODS,这说明不同保留机理的存在。研究表明,CCSP具有典型的反相色谱特征,但疏水性较ODS弱;除疏水作用外,n-π和π-π作用、氢键作用、电荷转移作用、偶极-偶极作用对分离也有贡献。CCSP对极性、电离性物质如水杨酸、对硝基苯甲酸、3,4,5-三羟基苯甲酸、邻苯二甲酸和邻溴苯甲酸等具有较强的保留;由于CCSP较弱的疏水性和多种分离机制,邻氯苯甲酸和苯甲酸在CCSP上的保留不会像在ODS上那么强,且分离度明显优于ODS。     

Electrophotochemical Metal-Catalyzed Decarboxylative Coupling of Aliphatic Carboxylic Acids

An electrophotochemical dual metal-catalyzed protocol for decarboxylative arylation of simple aliphatic carboxylic acids with aryl halides is reported. The relative stabilities of catalytically active metal complexes simultaneously generated at anode and cathode are the key design elements for the success of this convergent paired electrolysis. This new electrophotocatalytic method is mild, robust, and most importantly, capable of accommodating simple primary aliphatic acids including acetic acid – ubiquitous and variegated structural motifs yet remain oddly challenging substrates – directly as native functional groups for decarboxylative C(sp²)−C(sp³) bond formation.     

Methylation of Aliphatic and Aromatic Carboxylic Acids with Dimethyl Carbonate under the Influence of Manganese and Iron Carbonyls

The synthesis of methyl esters has been carried out via the reaction of aliphatic and aromatic carboxylic acids with dimethyl carbonate in the presence of manganese and iron carbonyls. The optimal ratio of catalyst and reagents and other conditions for the synthesis of methyl esters of carboxylic acids with high yield have been found.     

An Efficient Synthesis of Aromatic Iodides from Aromatic Carboxylic Acids

Aromatic iodides are prepared from readily available carboxylic acids via oxidative decarboxylation with iodosobenzene diacetate/iodine in carbon tetrachloride.     

离子液体作高效液相色谱流动相添加剂分离测定芳香族羧酸

以离子液体作反相高效液相色谱流动相添加剂,建立了分离测定对氨基苯甲酸、邻苯二甲酸、对羟基苯甲酸、水杨酸、苯甲酸、邻甲苯甲酸6种芳香族羧酸的方法。以C18反相色谱柱为分离柱,采用紫外检测方法,以离子液体作高效液相色谱流动相添加剂,考察了检测波长、甲醇含量、离子液体溶液的pH值、离子液体烷基链长度以及离子液体溶液浓度等分离及测定条件。优化得到的色谱条件为:以甲醇和1.0mmol/L 1-丁基-3-甲基咪唑四氟硼酸盐水溶液(pH 3.0)(体积比40∶60)为流动相;检测波长240 nm;流速1.0 mL/min;柱温30℃。在优化条件下对6种芳香族羧酸进行梯度洗脱,约在16.5 min内分离完全;在5~120 mg/L范围内,线性系数均在0.999以上;检出限为0.026~0.082 mg/L。方法的平均加标回收率为98.3%~103.8%,相对标准偏差不高于0.63%。将该方法应用于药品复方紫荆皮水杨酸溶液和足君清酊剂中芳香族羧酸的测定,结果满意。     

Free Radical Formation of p-Nitrophenacyl Esters of Carboxylic Acids and Their Detection by High-Performance Liquid Chromatography with Electron Spin Resonance

Abstract

p-Nitrophenacyl esters derived from p-nitrophenacyl bromide and carboxylic acids were determined by high-performance liquid chromatography with electron spin resonance. p-Nitrophenacyl bromide was used as the pre-column reagent to determine the carboxylic acids. The p-nitrophenacyl esters gave free radicals by hydrolysis with alkaline solution, and then the free radicals were detected with electron spin resonance. The separation of these esters was achieved within 20 min.     

Synthesis of D-Mannite Esters of Aliphatic and Aromatic Acids

Mono- and diesters of D-mannite with aliphatic acids and mixed diesters with aliphatic and aromatic acids were synthesized by transesterification of their methyl esters. The structures of the products are confirmed by PMR, ¹³ C NMR, and IR spectra