Determination of 3-mercaptopropionic acid by HPLC: A sensitive method for environmental applications

Abstract

The organic sulfur compound 3-mercaptopropionic acid (3-MPA) is an important thiol intermediate in organic sulfur metabolism in natural environments. It is generated during degradation of sulfur-containing amino acids (e.g. methionine) and from demethylation of dimethylsulfoniopropionate (DMSP). This pathway is an alternative enzymatic process in the DMSP catabolism that routes sulfur away from the climatically-active dimethyl sulfide (DMS). 3-MPA detection and subsequent quantification in different matrices is difficult due to its extreme reactivity. We therefore developed a sensitive method for determination of 3-MPA based on pre-column derivatization with monobromobimane and analysis by high-performance liquid chromatography (HPLC) with fluorescence detection. This methodology was first tested with 3-MPA standards under low (0.005-0.2μmolL(-1)) and high (1-25μmolL(-1)) concentrations. For the optimization of the reaction, CHES and, alternatively, Tris-HCl buffers were evaluated in the derivatization step, with Tris-HCl showing more effective separation of thiol derivatives and a better 3-MPA peak shape. The detection limit was 4.3nmolL(-1) with a 10μL sample injection, and mean recoveries of 3-MPA ranged from 97 to 105% in estuarine waters with different salinities (0.17 and 35.9ppt). The linearity (r>0.99) and repeatability of detector response, with intra- and inter-day precision (% CV) of 2.68-7.01% and 4.86-12.5%, respectively, confirmed the reliability of the method. Previous 3-MPA analytical methods required immediate analysis due to unstable derivatives, but in this method we achieved high stability of the derivatized samples when stored at 4°C, with only a 3-5% loss after more than one year of storage. This method was successfully applied to measure 3-MPA concentrations and rates of 3-MPA production in a variety of intertidal estuarine sediment slurries. Dissolved 3-MPA concentrations in these sediment slurries varied between 2 and 237μmolL(-1) and, 3-MPA net fluxes ranged in wet sediments between -3.6±1.7 and 30±5μmolL(-1)g(-1)h(-1). Thus, the application of this optimized methodology showed an efficient performance for measuring 3-MPA in environmental samples, with a straightforward sample derivatization and a simple analysis of stable 3-MPA derivatives.

Biodegradation tests of mercaptocarboxylic acids, their esters, related divalent sulfur compounds and mercaptans

“…Interestingly, 3-MPA was enzymatically oxidised to the corresponding sulfinic acid by a special bacterial mutant (Bruland et al 2009 ) and seems to be an intermediate in the metabolism of organic sulfur compounds (methionine, homocysteine) in natural environments (Salgado et al 2015 ; references cited therein).…”

Sulfur as a hydrogen bond donor in the gas phase: Rotational spectroscopic and computational study of 3-mercaptopropionic acid

“…Among sulfur-containing compounds, mercaptans (or thiols) (SH) are crucial in biological processes as well as in medicinal and food industries [15]. In particular, 3-mercaptopropionic acid (3-mpa) [HS-CH2-CH2-C(=O)OH] is an organic compound used in the synthesis of nanocrystals [16], peptides, and protein thioesters [17], and is a convulsant and important intermediate in biological studies [15,18].…”

“…Among sulfur-containing compounds, mercaptans (or thiols) (SH) are crucial in biological processes as well as in medicinal and food industries [15]. In particular, 3-mercaptopropionic acid (3-mpa) [HS-CH2-CH2-C(=O)OH] is an organic compound used in the synthesis of nanocrystals [16], peptides, and protein thioesters [17], and is a convulsant and important intermediate in biological studies [15,18]. Due to the potential of forming important metal complexes in seawater and sediments, 3-mpa complexes have also been used as prototypes for theoretical investigations [19] that aim to better understand the interaction between organic thiols and metal ions.…”

Fast microplate assay for simultaneous determination of thiols and dissolved sulfides in wastewater

“…These wavelengths have been selected for the course of this study. We deliberately chose MPA as the reference thiol compound herein because this compound has an important environmental significance [29] and possesses one of the higher pKa of thiol compounds [25], therefore requiring higher pH value than other thiols to reach optimal reaction yield (reaction scheme between MPA and EP is presented in Fig. S3).…”