High efficient extraction of phthalates in aquatic products by a modified QuEChERS method
A simple, environmentally friendly and high efficient extraction method was proposed for the determination of five phthalates in aquatic products by gas chromatography combined with mass spectrometry detector (GC-MS). When this method was adopted, samples were pretreated by modified QuEChERS(quick, easy, cheap, effective, rugged and safe) method. An environmentally friendly extractant(ethanol aqueous solution) replaced toxic acetonitrile for extracting phthalates in the protein-matrix samples. Fluorescence quenching spectra of bovine serum albumin(BSA) with phthalates show that there was a high-affinity interaction between phthalate and protein, decreasing the extraction efficiency of phthalates from fish samples. However, in the 80%(volume fraction, φ) ethanol aqueous solution, a slow but full protein denaturation takes place, which would cause the unfolding of protein and the release of phthalates. Meanwhile, the fat-soluble impurities are extracted less in φ(ethanol) 80% aqueous solution than in either φ(ethanol) 100% or hydrophobic solvents in the liquid-liquid extraction procedure. Therefore the purification steps were greatly simplified. Overall recoveries were 81.77%–90.5% with limits of detection between 2.53 and 9.61 μg/L, and relative standard deviation values at 1.15%–4.85%. The proposed approach was satisfactorily applied to the determination of phthalates in real aquatic products, such as fish, shrimp and oyster.