Fast low-pressurized microwave-assisted extraction of benzotriazole, benzothiazole and benezenesulfonamide compounds from soil samples

Benzotriazoles (BTRs), benzothiazoles (BTs) and benzenesulfonamides (BSAs), compounds largely used in industrial and household applications, are ubiquitous emerging contaminants. In this work a novel, straightforward procedure for the simultaneous determination of two BTRs (1H-benzotriazole, 5-methyl-1H-benzotriazole), three BTs (benzothiazole, 2-hydroxybenzothiazole, 2-methylthiobenzothiazole) and two BSAs (benzenesulfonamide, toluenesulfonamide) in soil has been developed. The target analytes were extracted from soil by a single low-pressurized microwave-assisted extraction (MAE) cycle (120 degrees C, 10 min) and quantified by high-performance liquid chromatography with UV detection. For all the seven analytes, quantitative extraction yields (72-119%, n=4) were observed from recovery tests on soil samples (1 g) spiked with 5, 10 and 50 mg kg(-1), using 4 mL water-methanol (85:15) as extracting solution. For the lower concentrations levels (100, 250 and 500 mu g kg(-1)), the analytes were extracted from soil samples (2-3 g) using 6 mL methanol, and the extract was pre-concentrated by evaporation before analysis; recoveries in the range 70-117% were obtained (n=4). Suitable intra-day and inter-day precision were observed, with values of relative standard deviation generally below 6% and 11% (n=4), respectively. Linearity was evaluated in the concentration range 0.5-10 mg L-1 by matrix-matched standards, obtaining r(2) >0.9996. The experimental method quantification limit (MQL) was 100 mu g kg(-1). The entire procedure has been successfully applied to the analysis of real impacted soil samples. (C) 2015 Elsevier B.V. All rights reserved.