Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

E Karicheva,N Guseva,M Kambalina

doi:10.1088/1755-1315/33/1/012006

Abstract

Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula.The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

Highlights

Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements [1]
The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography
High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L, from 0.1 mg/g to 25 mg/L

Summary

Introduction

Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements [1]. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils [2,3,4]. Identification of individual carboxylic acids remains quite challenging due to the low concentrations of these compounds in natural water and soils and their physicochemical properties. Carboxylic acids are unstable compounds which undergo degradation during sample preparation, such as extraction or concentration [9,10]. Ion chromatography (IC) as the most preferred method of analysis has been widespread in recent years due to relatively simple equipment, the most effortless sample preparation, and the use of different modes of operation, such as gradient elution [11,12]

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Conclusion