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

Abstract

A new analytical method has been developed for the screening, evaluation and determination of sub µg/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 100 mL sample volume, 5% MeOH, 10% NaCl and an extraction time of 14 h of mechanized stirring, which provided best analytical recoveries. Desorption of analytes was carried out using 5 mL acetonitrile (ACN) and 5 min of two successive sonication steps which resulted best performance without any carry over. The method detection limits (MDL) ranged 3–22 ng/L and 7–29 ng/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, α-endosulfan and endosulfan sulphate were positively identified in river waters and three compounds viz., chloropyriphos-ethyl, α-endosulfan and endosulfan sulphate were detected in wastewater effluents. The concentrations of α-endosulfan ranged between 11.3–22.9 ng/L and 16.3–33.8 ng/L in river waters and wastewaters respectively. Almost 40% of the water samples analysed showed much higher concentrations of α-endosulfan than prescribed European environmental quality standard limit for surface waters of 5 ng/L.

Keywords:

• chlorinated HACs
• stir bar sorptive extraction
• GC-QqQ-MS
• negative chemical ionization
• liquid desorption
• river water
• wastewater effluents

Acknowledgements

N. Sridhara Chary would like to thankfully acknowledge the Marie-Curie Actions for providing AMAROUT fellowship. The authors acknowledge the Spanish Ministry of Science and Innovation (Project CTM2011-27657) and Programa Consolider Ingenio 2010 (CE-CSD 2006–00044) for financial assistance.