Determination of hormonally active chlorinated chemicals in waters at sub μg/L level using stir bar sorptive extraction-liquid desorption followed by negative chemical ionization-gas chromatography triple quadrupole mass spectrometry

A new analytical method has been developed for the screening, evaluation and determination of sub mu g/L concentrations of chlorinated chemicals in environmental waters. Ten different compounds included in the European water policy have been considered and determined by stir bar sorptive extraction (SBSE) followed by liquid desorption and negative chemical ionization gas chromatography coupled to triple quadrupole mass spectrometry (SBSE-LD-NCI-GC-QqQ-MS). Analyte extraction was performed using SBSE with 100mL sample volume, 5% MeOH, 10% NaCl and an extraction time of 14h of mechanized stirring, which provided best analytical recoveries. Desorption of analytes was carried out using 5mL acetonitrile (ACN) and 5min of two successive sonication steps which resulted best performance without any carry over. The method detection limits (MDL) ranged 3-22ng/L and 7-29ng/L for river waters and wastewaters respectively. The experimental recoveries for all compounds were>60% with<20% deviation in the reproducibility. Pentachloroanisole alone reported a low maximum recovery of 54% under given conditions. Matrix influenced signal enhancement was observed more in case of triclosan, which was managed by using matrix matched calibration standards apart from using double helix injection liner. This method was applied to the analysis of different river waters and wastewater effluent samples collected from Alcala de Henares, Spain. Four compounds namely chloropyriphos-ethyl, triclosan, -endosulfan and endosulfan sulphate were positively identified in river waters and three compounds viz., chloropyriphos-ethyl, -endosulfan and endosulfan sulphate were detected in wastewater effluents. The concentrations of -endosulfan ranged between 11.3-22.9ng/L and 16.3-33.8ng/L in river waters and wastewaters respectively. Almost 40% of the water samples analysed showed much higher concentrations of -endosulfan than prescribed European environmental quality standard limit for surface waters of 5 ng/L.