Determination of organic acids in biological fluids by ion chromatography: plasma lactate and pyruvate and urinary vanillylmandelic acid.

Abstract

We describe the general aspects of ion chromatography and how on-line counted ion-exchange techniques can be utilized to determine pyruvic and lactic acids in plasma and vanillymandelic acid in urine. Pyruvate and lactate are extracted from deproteinized plasma by use of an ion-exclusion resin. After elution from the resin, the plasma extract is chromatographed on an anion-exchange column, with 0.66 mmol/L sodium bicarbonate as the mobile phase. The effluent is detected with an electrical conductivity cell. Vanillylmandelic acid is extracted from diluted urine by use of an anion-exchange resin. After elution from resin, the urine extract is chromatographed on an ion-exclusion column, followed by electrochemical detection. We evaluated the procedures for precision, linearity, analytical recovery, intefering substances, and correlation with an established procedure. the combination of a preliminary resin extraction, an ion chromatographic separation, and a conductivity or electrochemical detector results in rapid, specific methods that can be adapted for use in the clinical laboratory. Preliminary data for other organic acids are presented.

Combined approach of NMR and chemometrics for screening peptones used in the cell culture medium for the production of a recombinant therapeutic protein

“…Alternatively, lactate levels in the solutions were directly measured by a commercial blood gas analyzer equipped with a lactate amperometric enzyme electrode. Moreover, reversed-phased HPLC or ion chromatographic methods can be developed to determine the levels of lactate in peptones based on a number of methods reported in literature (Bleiberg et al, 1991;Rich et al, 1980;Simonides et al, 1988). Despite the readiness of lactate measurement by means of analytical techniques other than NMR, the PCA prediction is more robust than the one using lactate level alone because all NMR features that are positively or negatively correlated to the titer performance were taken into account throughout the entire spectral region.…”

Reply to “Comment on ‘Reactivity of Ketyl and Acetyl Radicals from Direct Solar Actinic Photolysis of Aqueous Pyruvic Acid’”

“…E&G have advanced previous efforts by quantifying the generation of 2,3-dimethyltartaric acid, acetic acid, and the oxo-C 7 and oxo-C 8 products by combining the use of separations by UHPLC and IC coupled to MS, HRMS, the assignment of one-dimensional (1D) 1 H and 13 C NMR and two-dimensional (2D) 13 C gCOSY spectroscopic features, as well as by employing quantitative 1 H NMR (qNMR) . The chromatographic separations were performed both with reversed-phase C18 and alkanol quaternary ammonium columns with high specificity to separate monocarboxylic, dicarboxylic, and oxocarboxylic acids prior to UV–visible, conductivity, and MS detection. , In addition, these analyses included the separation, identification, and quantification of carbonyls (CO) in the mixture of photoproducts treated with 2,4-dinitrophenylhydrazine (DNPH). ,, The undeniable power of these techniques for the analysis of this class of products, , with low limits of detection (LOD) also makes them excellent for the determination of lactic acid (LOD = 86 nM) and acetoin (LOD = 330 nM) after chromatographic separation, as exemplified by applications for food industry and clinical settings. − The work of E&G used standard addition of lactic acid and acetoin directly into the samples, providing an unambiguous comparison of the spectroscopic features and facilitating the quantification process . Furthermore, the multiple analytical techniques employed and listed above, not only HRMS as stated by V&C, provided confirmation that a major oxo-C 7 product is observed both in experiments under 1 atm air or in controls under 1 atm N 2 (g) …”

Peer Reviewed: Ion Chromatography Retrospective

“…Many other eluent ions, which were the conjugate bases of weak acids (e.g., borate), were amenable to suppression and used for specific separations. Using similar technology and making some changes to the detection system, researchers developed suppressed IC into a technique that successfully separates inorganic cations (often with color-forming postcolumn reactions as the basis of detection [12]), organic acids and bases (13), carbohydrates (14), and amino acids (15).…”