Application of three-phase hollow fiber liquid-phase microextraction for analysis of hydroxybenzoic acids
三相中空纤维液相微萃取在羟基苯甲酸类化合物分析中的应用

Under the optimal experimental conditions of three-phase hollow fiber liquid-phase microextraction (3p-HFLPME) , the behaviors of hydroxybenzoic acids (HBAs) were investiga-ted. The correlativities between the enrichment factor (EF) of HBAs and their n-heptanol/wa-ter conditional distribution coefficients (log P_(n-heptanol/5mmol/L HCl), pK_a and the number of -OH (N); the extraction mechanism that polyvinylidene difluoride hollow fiber contributed to pro-mote the extraction efficiency by forming charge transfer compound with HBAs and the organic solvents showed notable selectivity for HBAs were elucidated. The optimal 3p-HFLPME condi-tions were: MOF 503 polyvinylidene difluoride hollow fiber as organic solvent supporter, n-hep-tanol as organic phase, 5 mmol/L HCl in the donor phase and 80 mmol/L NH_3·H_2O as the ac-ceptor phase, the HBAs were extracted for 35 min under an agitation of 1 200 r/min. It was found that the relative standard deviations were lower than 3%, the detection limits were 0. 09 -30. 00 μg/L, the average recoveries of HBAs in Calyx Kaki were 93. 3%-107. 1% and the EF of HBAs at 5 mg/L was up to 107. 6 fold.