Development and validation of multi-residuemethod for the determination of persistent organic pollutants in soil by gas-chromatography- tandem-mass-spectrometry

Author(s): Samuel K.Frimpong, Ray B.Voegborlo, Philip O.Yeboah, Samuel B.Dampare

A multi-residue method capable of determining simultaneously organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in soil samples by gas-chromatograph- tandem-mass-spectrometrywas developed, optimized and validated. Soil sampleswere extracted by two optimized extraction techniques; sonication and mechanical shaking with acetonitrile as extracting solvent. The extract was cleaned-up with solid phase extraction cartridge of amino sorbent topped with 1g anhydrous magnesium sulfate to remove matrix interferences and residual moisture, respectively. Final determination of extract which contains 1% polyethylene glycol-200 in ethyl acetate to enhance and improve separation was done by gas chromatography (GC) with mass spectrometric detection (MSD). Average recoveries by the GC”MS/MS validated method varied from 70% to 110% with relative standard deviation between 2.0% and 12.0% for amino sorbent cartridge. The method presents good linearity over the range of 0.005"1.0µg/mL, and the quantification limit for the analytes studied varied from 0.1 to 1.0 µg/ kg. The method proved to be very rugged for other related soil types. The proposed method shows practical environmental and economic advantages in terms of sample processing time, simplicity, relatively safer and reduced organic solvent use and cost, and is particularly suitable for routine applications requiring a high sample throughput.

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