HPLC-MS/MS Determination of 23 Phthalate Esters in Naturally Colored Cotton

HPLC-MS/MS was applied to the determination of 23 phthalate esters in naturally colored cotton. The sample of naturally colored cotton was crushed,and then 1.000 0 g of powder weighed was extracted ultrasonically with 30 mL of methanol for 30 min. The extract was concentrated by distillation and blown to near dry with nitrogen. The residue was taken up with methanol and diluted to 1 mL with methanol. The solution was filtered on 0.45 μm organic filtering membrane. Kinetex-C₁₈ chromatographic column was used as stationary phase, and the mixture of methanol and 0.1% (φ) formic acid solution mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and multi-reactions monitor mode were adopted in MS/MS. Linear relationships between values of peak area and mass concentration of the 23 phthalate esters were kept in the same range of 0.01-0.50 mg·L^-1, with detection limits (3S/N) in the range of 0.01-4.05 μg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 85.2%-105%, with RSD's (n=6) in the range of 0.60%-12%.