Quantitative determination of chlorophenols in leather by pressurized liquid extraction and liquid chromatography with diode-array detection

Pressurized liquid extraction (PLE) with acetonitrile was used for the recovery of chlorophenols (4-chloro-3-methylphenol, 4-chloro-2-methylphenol, 2,4-dichlorophenol, 2-phenylphenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol) present as biocides in leather. After a single cycle PLE treatment, solutions underwent pre-concentration by evaporation of the solvent under vacuum and clean-up treatment with solid-phase extraction cartridges. Quantitative analysis of the target compounds was carried out by liquid chromatography with gradient elution and UV spectrophotometric detection at variable wavelength for the various analytes in the range 190–240 nm. Instrumental detection limits and operative detection limits in the real matrices were determined according to the Hubaux-Vos approach and to the US Environmental Protection Agency procedures. The detection limits for the seven analytes ranged from 10 to 70 μg kg−1. Linearity was very good in the explored range (10−7–10−5 M) giving R2 values from 0.995 to 1.000 for pentachlorophenol and 2,4-dichlorophenol, respectively. Repeatability was satisfactory, 2–5% for a 1 × 10−6 M level of concentration, on five repeated measurements on the sample. Recovery yield values with the proposed procedure were determined using spiked samples. Overall recovery ranged from 88 to 97%. The method was used for routine analysis of real leather samples.