Determination of Fumaric Acid, Maleic Acid, and Phthalic Acid in Groundwater and Soil

Abstract

When present at < 1 μg/mL, each title compound was determined in groundwater by ion-exclusion chromatography after sample acidification and filtration. For groundwater with one or all analyte concentrations of < 1 μg/mL, the acid anions were first concentrated from a 100-mL sample using a quaternary amine anion-exchange cartridge. The acids were recovered by eluting the cartridge with 1 mL of 1 N H₂SO₄ and two 2-mL deionized water washes; this solution then was examined by anion-exclusion chromatography. For soil, the acids were extracted from a 10-g sample with 20 mL of 1 N H₂SO₄ and two 15-mL water washes. This extract was filtered then analyzed by anion-exclusion chromatography. All analyses used 25-μL injections into the HPLC column which was maintained at 60°C and eluted with a 0.6 mL/min. flow of 0.02 N H₂SO₄. Analytes were monitored with a UV detector operated at 200 nm. The analysis procedures for groundwater were validated with solutions which were fortified with from 50 ng/mL to 200 μg/mL of each analyte; recoveries ranged from 90 to 110%. The soil method was validated using fortified samples which contained each acid at concentrations of from 5 to 160 μg/g. Recovery values were between 81 and 120%. For samples exhibiting minimal detector response from compounds other than the acids of interest, 100-μL injection volumes provided an estimated detection limit of 1 μg/g for soil and 10 ng/mL for groundwater.