Determination of phthalate sum in fatty food by gas chromatography

Presented method for determination of sum of phthalates is based on their alkaline hydrolysis to phthalic acid at 80 °C for 20 h, followed by the selective extraction of lipophilic interferents from acidified hydrolysate at pH 1 with n-hexane. Phthalic acid is derivatized to dimethyl phthalate (DMP) with diazomethane in aqueous-chloroform two-phase system. Resulting DMP is absorbed in chloroform and determined by GC-FID. Method calibration resulted in LOD and LOQ of 0.4 (2.1) and 1.2 (6.2) μg g−1 (nmol g−1) DMP, respectively. Real samples of Baltic herring and codfish, butter, pork, goose and duck fats, sunflower, olive, rapeseed and linseed oils were analysed and the background corrected total phthalates content was found in the range from not detected level in duck fat to 12.5 (64.3) μg g−1 (nmol g−1) in butter, respectively.