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

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℃. 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.