Field sample preparation of trace inorganic anions in environmental waters with in-tip microextraction device based on anion-exchange monolithic adsorbent followed by ion chromatography quantification

Abstract

In this study, a new field preparation method for the quantification of inorganic anions (including F−, BrO3−, Cl−, NO2− and Br−) at trace levels in environmental waters was proposed and developed. Glycidyl methacrylate was copolymerized with ethylene dimethacrylate in a pipette tip to obtain epoxy group-rich monolith, and then trimethylamine was employed to perform ring-opening reaction and got anion-exchange monolithic adsorbent (AMA). The resultant adsorbent was used as the extraction medium of three-channel in-tip microextraction device (TCMD) which was employed to conduct field sample preparation of inorganic anions in different water samples followed by analysis with ion chromatography with conductivity detector (IC/CD). The AMA exhibited satisfactory capture capability to studied anions through anion-exchange interaction. After optimization of extraction parameters, a method with low limits of detection (LODs, 0.019–0.33 μg/L), satisfactory coefficients of correlation (0.9925–0.9985) and good precision (RSDs ≤ 10%) was developed. The introduced approach was successful applied to detect studied anions in environmental waters, and the fortified recoveries varied from 77.3 to 113%. Additionally, the accuracy of suggested method was inspected by confirmatory testing. Compared with reported methods, the current approach displays some attractive features such as semi-automation, high throughput and low LODs. The suggested AMA/TCMD for on-site preparation of inorganic anions not only circumvents the storage and transportation of a great quantity of waters, but also ensures the quantification accuracy.