Determination of benzothiazole in untreated wastewater using polar-phase stir bar sorptive extraction and gas chromatography-mass spectrometry

Stir bar sorptive extraction (SBSE) was applied to extract benzothiazole (BT) from untreated wastewater using a novel polyacrylate (PA)-coated stir bar (PA Twister^®). After extraction, BT was desorbed in a thermal desorption system (TDS) and analysed by GC–MS (gas chromatography–mass spectrometry). The sample contained 30% (w/w) NaCl, the sample temperature was 30 °C and the extraction time was 240 min. Since no filtering or clean-up steps or solvents were necessary SBSE clearly performs better than all previously used extractions techniques for analysing BT in untreated wastewater in terms of easy use, sample throughput and analytical costs. In addition, matrix effects were small. The calibration curve resulting from the standard addition method was linear with a value of the stability index (R²) of 0.999 (n = 3). A good inter-day repeatability of the method was observed with a relative standard deviation (RSD) of 9.8% (n = 6). A low limit of detection (LOD) of 0.256 μg L⁻¹ was achieved using only a small sample volume of 18 mL. Small sample volumes significantly reduce sample transport costs. The concentration of BT in untreated wastewater was determined to be 1.04 μg L⁻¹.