Determination of superabsorbent polyacrylate dust in workplace atmospheres after derivatization with ethanol and using HPLC with pulsed electrochemical detection

Abstract

Superabsorbent polyacrylates (SAPs) have been used in the hygiene industry for many years. A derivatization and analytical method was developed for routine analysis of trace levels of SAP dust in workplace atmospheres. In comparison with existing methods, which are based on the sodium content or the ion exchange properties of the polymer, this method is more specific. It has the advantage of not being influenced by any sodium containing contaminants. Air samples are collected on Teflon filters using air monitoring sampling cassettes. The filters are subsequently placed in quartz vials and a reaction mixture containing hydrochloric acid in ethanol is added. The hydrochloric acid–ethanol solution, when heated, converts the carboxylic acid groups on the backbone of the insoluble polyacrylate into ethyl esters. After reaction, the excess of ethanol and hydrochloric acid is completely removed under vacuum. The sample is then treated with aqueous sodium hydroxide at 80 °C to release the bound ethanol. The solution is analyzed by HPLC on an anion exclusion stationary phase using dilute perchloric acid as mobile phase. Ethanol is identified and quantified with a pulsed electrochemical detector. Several environmental samples in addition to laboratory spiked samples were successfully analyzed with this technique. Recoveries averaged >85% for spiked blank filters at levels from 5 to 50 μg per filter with relative standard deviations up to 7%. The instrument’s limit of detection (LOD) for ethanol was 0.1 mg l⁻¹. The LOD for derivatization and analysis corresponds to 3 μg of SAP per filter (assuming an esterification factor of 0.30 μg of ethanol per μg of SAP).