Abstract:In this study, an analytical method based on high-performance liquid chromatography(HPLC) was established for the determination of ε-PLH in food by optimizing the mobile phase, extraction reagents and solid-phase extraction conditions and so on. ε-PLH was extracted twice with 0.3 mol.L-1 sodium dihydrogen phosphate solution(pH value=3.0), degreased by dichloromethane. The extract was centrifuged at 8000 r.min-1 for 5 min, and the supernatant was cleaned up on an AL-B solid-phase extraction column, and then eluted with 30% ammonia solution(v/v). Separation of ε-PLH was performed on a hydrophase gel column( Protein SEC-400, 300 mm×8.0 mm, 5 μm) by isocratic elution using 0.3 mol.L-1 sodium sulfate solution (pH value=3.0) as the mobile phase. The analyte was identified by DAD detector(λ=210 nm). Quantification was achieved using external standards．The retention time of ε-PLH was 8.2 min. ε-PLH demonstrated good linearity in the range of 5~200 μg.mL-1，with linear correlation coefficient (r2) greater than 0.99．The limit of detection(LOD) was 15 mg.kg-1, and the limit of quantification(LOQ) was 50mg.kg-1. The recoveries were investigated in six types of food matrices, such as jam, big rice noodles, vinegar, drinks, fried flour products, miscellaneous grain products and so on. The recoveries of ε-PLH ranged from 90.74% to 106.07% at the three spike levels of 1LOQ, 2LOQ and MRL, respectively, with relative standard deviations (RSDs) ranging from 1.85% to 5.24%(n=6). The results show that the method has high stability, strong applicability and anti-interference ability, good sensitivity and reproducibility, which provide technical support for the monitoring of ε-PLH content in imported and exported food and the formulation of standards.
