[Determination of six p-hydroxybenzoates in fruits and jams using solid-phase extraction-high performance liquid...

A method was developed for the determination of 6 p-hydroxybenzoates (methyl p-hydroxybenzoate (MHB), ethyl p-hydroxybenzoate (EHB), isopropyl p-hydroxybenzoate (IPHB), propyl p-hydroxybenzoate (PHB), isobutyl p-hydroxybenzoate (IBHB) and butyl p-hydroxybenzoate (BHB)) in fruits and jams using the combination of solid-phase extraction and high performance liquid chromatography (SPE-HPLC). Two different extraction solutions and three different mobile phases were tested for p-hydroxybenzoates analysis, and finally ethanol was used as the extraction solvent and methanol-citric acid buffer was selected as the mobile phase. The sample was extracted, and purified by an Oasis HLB solid-phase extraction cartridge, then separated on a Symmetry-C18 column and detected at the wave length of 258 nm. The results showed that all the calibration graphs were linear in the concentration range of 0.1 -20.0 mg/L (r = 0.9999). The detection limits and quantification limits were 0.1 mg/kg (S/N = 3) and 0.3 mg/kg (S/N = 10) respectively for MHB, EHB, IPHB and PHB, 0.2 mg/kg (S/N = 3) and 0.6 mg/kg (S/N = 10) respectively for IBHB and BHB. The average recoveries were between 82.8% and 115.5% with the relative standard deviations (RSDs) of 0.2%-6.8% (n = 6). The method is simple, rapid, sensitive and reproducible, and can be used for the routine analysis of the p-hydroxybenzoates in fruits and jams.