Highly Sensitive Determination of Contaminants in Surface Water in the Context of the EU Water Framework Directive using Stir Bar Sorptive Extraction (SBSE) and GC-MS/MS

Abstract

App Note 196/2018

In the work presented here, highly sensitive determination of around 100 contaminants in surface water in the concentration range from low double digit to low triple-digit pg/L was performed. Priority compounds from the EU water framework directive (EU-WFD) as well as substances from other legislation were included. A sequential stir bar sorptive extraction (SBSE) approach employing the GERSTEL Twister was used for analyte enrichment from 100 mL water samples. The Twister was thermally desorbed, compounds were separated via GC and detected by tandem mass spectrometry (MS/MS) utilizing an Agilent 7010 MS. The analysis method was comprehensively validated and requirements of the EU-WFD for inland surface water were fulfilled. Repeat analyses of water samples spiked at concentrations close to the Limits of Quantification (LOQ) of the respective analytes demonstrated relative standard deviations between 1 and 15% with an average of 6.9%. Trueness was mainly between 90 and 110%. The correct quantitation of particle-adsorbed
compounds like PAHs was examined and confirmed using certified reference sediment.

Cypermethrin, heptachlor and heptachlorepoxide were the only compounds for which the required LOQs could not be reached. To date there is no technique known to the authors that reaches the required LOQs of 0.06 pg/L for heptachlor and heptachlorepoxide. The developed analysis method was successfully applied to real world water samples.