Method for the simultaneous determination of the most problematic families of organic pollutants in compost and compost-amended soil

Abstract

Linear alkylbenzene sulfonates (LAS), nonylphenol ethoxylates (NPE; sum of nonylphenol, nonylphenol monoethoxylate, and nonylphenol diethoxylate), and di-(2-ethylhexyl)phthalate (DEHP) are the most problematic organic pollutants in sludge owing to their high concentrations and the concentration limits of 2,600, 50, and 100 mg/kg, respectively, proposed in the European Union directive draft for land application of sludge. In this paper, an analytical method for the simultaneous determination of the C(10), C(11), C(12), and C(13) LAS homologues, the nonylphenolic compounds nonylphenol, nonylphenol monoethoxylate, and nonylphenol diethoxylate, and di(2-ethylhexyl)phthalate in compost and compost-amended soil is proposed. The method is based on sonication-assisted extraction, cleanup by solid-phase extraction, and determination by high-performance liquid chromatography with diode-array and fluorescence detectors. The mean recoveries of LAS, NPE, and DEHP were 83, 87, and 79%, respectively, in compost samples, and 77, 96, and 99%, respectively, in compost-amended soil samples. The limits of detection and quantification in compost samples were lower than 6.77 and 22.3 mg/kg dry matter, respectively, for LAS; lower than 7.34 and 22.8 mg/kg dry matter, respectively, for NPE; and 0.78 and 1.18 mg/kg dry matter, respectively, for DEHP. The limits of detection and quantification in compost-amended soil samples were lower than 0.03 and 0.10 mg/kg dry matter, respectively, for LAS; lower than 0.04 and 0.12 mg/kg dry matter, respectively, for NPE; and 0.03 and 0.10 mg/kg dry matter, respectively, for DEHP. The method was successfully applied to compost and compost-amended soil samples from Seville (south of Spain).