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

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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°C, 10min) 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 (1g) spiked with 5, 10 and 50mgkg−1, using 4mL water-methanol (85:15) as extracting solution. For the lower concentrations levels (100, 250 and 500μgkg−1), the analytes were extracted from soil samples (2–3g) using 6mL 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 0.5–10mgL−1 by matrix-matched standards, obtaining r2>0.9996. The experimental method quantification limit (MQL) was 100μgkg−1. The entire procedure has been successfully applied to the analysis of real impacted soil samples.