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

在优化的三相中空纤维液相微萃取(3p-HFLPME)条件下,研究了6种羟基苯甲酸类化合物(HBAs)的3p-HFLPME行为;揭示了HBAs的富集因子(EF)与其正庚醇/水条件分配系数(log Pn-heptanol/5 mmol/L HCl)、pKa和羟基数目(N)的相关性,初步阐明了聚偏氟乙烯中空纤维对HBAs的电荷转移传递机理以及有机溶剂对HBAs的选择性萃取机理。优化的3p-HFLPME条件: 以MOF 503聚偏氟乙烯中空纤维为有机溶剂支持体,正庚醇为有机相,5 mmol/L HCl体系为给体,80 mmol/L NH3·H2O为接受相,搅拌速度为1200 r/min,萃取35 min。该方法的精密度（以相对标准偏差计）小于3%,检出限为0.09~30.00 μg/L,加标回收率为93.3%~107.1%,HBAs质量浓度为5 mg/L时的富集因子最高达107.6倍。

Application of three-phase hollow fiber liquid-phase microextraction for analysis of hydroxybenzoic acids

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.