Liquid-Chromatographic Methods for Carboxylic Acids in Biological Samples

Abstract

Carboxyl-bearing low-molecular-weight compounds such as keto acids, fatty acids, and other organic acids are involved in a myriad of metabolic pathways owing to their high polarity and solubility in biological fluids. Various disease areas such as cancer, myeloid leukemia, heart disease, liver disease, and lifestyle diseases (obesity and diabetes) were found to be related to certain metabolic pathways and changes in the concentrations of the compounds involved in those pathways. Therefore, the quantification of such compounds provides useful information pertaining to diagnosis, pathological conditions, and disease mechanisms, spurring the development of numerous analytical methods for this purpose. This review article addresses analytical methods for the quantification of carboxylic acids, which were classified into fatty acids, tricarboxylic acid cycle and glycolysis-related compounds, amino acid metabolites, perfluorinated carboxylic acids, α-keto acids and their metabolites, thiazole-containing carboxylic acids, and miscellaneous, in biological samples from 2000 to date. Methods involving liquid chromatography coupled with ultraviolet, fluorescence, mass spectrometry, and electrochemical detection were summarized.

An Optimized Method for LC–MS-Based Quantification of Endogenous Organic Acids: Metabolic Perturbations in Pancreatic Cancer

“…For quantification purposes, we developed a specific MRM pair as (Q1 > Q3; 281.288 > 166.06) for cis-aconitic acid ( Supplementary Table S1, entry 39 ). The parent ion at 237.259 was reflective of a linear derivative from one carboxylic acid group, which may be indicative of citric acid degradation to citraconic acid/itaconic acid ( Supplementary Table S1, entries 39 and 40 ) [ 22 ]. While we also observed 511.021 > 248.9438 and 493.074 > 338.9858 MRM pairs, the transition 237.259 > 166.115 was selected for quantification of citric acid, and the quantification results are the sum of citric, iso-citric, itaconic, and citraconic acids.…”

Exploring Novel Applications for Hydrogels Derived from Modified Celluloses

“…Due to the absence of a chromophore in carboxylic acid, UV absorbance detection is rarely utilized. Ion exchange chromatography detection, offering high sensitivity, is more commonly employed [ 36 ]. In the 3D printing process, bioinks have distinct requirements before, during, and after extrusion.…”

Use of N‐(4‐aminophenyl)piperidine derivatization to improve organic acid detection with supercritical fluid chromatography‐mass spectrometry

“…Ion-exchange chromatography has also been used for the separation of organic acids, although challenges exist when coupling this technique to MS [10]. A recent review detailed such methods used for the analysis of these compounds in biological samples by LC [11]. Because of their carboxylic acid functional groups, these compounds are typically detected by ESI-MS in negative mode, which generally suffers from lower signal intensity than positive mode [11][12][13].…”

“…A recent review detailed such methods used for the analysis of these compounds in biological samples by LC [11]. Because of their carboxylic acid functional groups, these compounds are typically detected by ESI-MS in negative mode, which generally suffers from lower signal intensity than positive mode [11][12][13]. These challenges provide motivation for the development of new analytical techniques for the analysis of organic acids.…”