Phthalate sum determination in farmland soils using high-performance liquid chromatography-tandem mass spectrometry.

A selective and low organic-solvent-consuming method of sample preparation combined with high-performance liquid chromatography and tandem mass spectrometry is introduced for phthalate sum analysis in farmland soil. Sample treatment involves a one-step hydrolysis of phthalates using methanol and alkaline and tetrabutylammonium bromide for 20 min at 80 degrees C. Then, the resulting phthalic acid in the acidified hydrolysate is extracted using an octanol-based supramolecular solvent without purification. Under optimized conditions, the correlation coefficients were 0.992-0.999 and standard errors (S-y/x) were 0.018-0.138 for calibration curves within the range of 50-2000 ng/mL. No obvious matrix effect occurred between the pure supramolecular solvent and soil extract. The recovery rates ranged from 91 to 107% with the relative standard deviation ranging from 0.5-7.3%. Intra-and interday repeatability, expressed as relative standard deviation, was less than 8.0 and 11.0%, respectively. The detected limit was 2.49 nmol/g, and the quantification limit was 3.64 nmol/g. Fifteen soil samples were analysed, and the background corrected phthalate sum ranged from 1.44 to 120 nmol/g.