Direct immersion thin film solid phase microextraction of polychlorinated n-alkanes in cod liver oil

A thin film-solid phase microextraction (TF-SPME) method was developed to test for 5 individual polychlorinated n-alkanes (PCAs) from commercial cod liver oil samples. This was accomplished by preparing a novel aluminum supported, hydrophilic-lipophilic balance/polydimethylsiloxane (HLB/PDMS) TF-SPME device that enabled direct immersion extraction from fish oil. Matrix-matched calibration gave a linear range from 0.075 µg/g to 0.75 µg/g with method limits of quantitation (MLOQ) ranging from 0.07 µg/g to 0.217 µg/g in oil. Standard addition calibration was performed using other fish oils demonstrating comparable slope to the external calibration. As a proof of concept, four fish oil brands were tested for contaminants; 1,1,1,3-tetrachlorodecane, 1,2,9,10-tetrachlorodecane, 1,2,13,14-tetrachlorotetradecane, and 1,1,1,3,14,15-hexachloropentadecane were detected above the MLOQ but below the range provided by the Stockholm Convention. This method provides an effective approach for cleanup and preconcentration of PCAs from oily matrices using inexpensive, and reusable microextraction devices that limit environmental impact of the sample preparation protocol.