Optimizing a simple procedure to determine organochlorine compounds in sediment samples: practical considerations†
Eighteen organochlorine compounds were determined in contaminated sediments using small amounts of sample (0.25 g) and solvent (1 mL, dichloromethane). This involved the optimization and evaluation of a quick vortex-assisted extraction. Target compounds included pentachlorobenzene, hexachlorocyclohexanes (α, β, γ), hexachlorobenzene, DDE/DDD/DDT (o,p′ and p,p′ isomers) and PCBs (no. 28, 52, 101, 118, 138, 153 and 180). Involved assays were accomplished by analyzing real contaminated samples without previous spiking and using gas chromatography with a mass detector (GC/MS). As interesting aspects, a light oven drying with subsequent grinding and the addition of purchasable copper to remove sulfur were found to make the proposed procedure more affordable. In addition to describing the development of the analytical procedure, the reliability of the results was also assessed. In detail, the presence of possible bias and intermediate precision were estimated. The absence of bias in the analytical results was investigated by the Youden method. Regarding analytical variability, intermediate precision was estimated from the overall analyses of different real samples. Values were mainly between 6 and 15%, except for the DDT isomers, DDE and HCH, which ranged from 15 to 30%. The limits of detection (LODs) ranged from 0.1 to 0.7 ng mL−1. This study describes a simple method for determining organochlorines in sediments, which can be easily conducted in routine laboratories.