A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation method coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was proposed for the determination of α-, β-, and γ-hexabromocyclododecane (HBCD) diastereomers in whole-fish homogenate samples. The main modification of the QuEChERS method concerned a clean-up step in which the combination of pH-tuned dispersive liquid–liquid microextraction (DLLME) with 18.4 M H2SO4 digestion allowed to successfully eliminate the matrix substances from the final extract. For the target HBCDs, good response linearity was obtained with coefficients of determination (R2) >0.998 for the concentration range corresponding to 0.1–50 ng of analyte per g of sample. Limits of quantifications (LOQs) were 0.15–0.25 ng g−1 ww (wet weight), and the recoveries from samples spiked at levels of 0.5 and 5 ng g−1 ranged from 89% to 102% with relative standard deviations <7.5%. The accuracy of the method was verified by analysis of the NIST standard reference material SRM 1947, and a good agreement (90%) was obtained with the certified value for the α-HBCD present in the sample. Finally, the method was applied to the analysis of 293 fish samples collected in water bodies from all over Slovakia, in which the highest concentrations were determined for α-HBCD with the maximum value of 31 ng g−1 ww.
Determination of Chlorsulfuron and Pendimethalin in Soil Samples Using Modified QuEChERS Method by Liquid Chromatography-Tandem Mass Spectrometry
