Determination of L-hydroxyproline using hydrophilic interaction chromatography coupled to tandem mass spectrometry with lyophilized concentrated extraction in milk and dairy products

摘要

In this study, a screening and confirmation method for the determination of Lhydroxyproline (Hyp) as a target compound in milk and dairy products using highperformance liquid chromatography with tandem mass spectrometry was developed. The samples were lyophilized after acidic hydrolysis, followed by cleanup with graphitized carbon black to remove pigments. Hyp was separated by a hydrophilic interaction chromatographic column and analyzed by high-performance liquid chromatography with tandem mass spectrometry working with multiple reaction monitoring mode using an electrospray ionization interface in a positive-ionmode. Average recoveries in spikedmilk and dairy products ranged from 68.0 to 101.1% with relative standard deviations between 2.0 and 11.7% (n = 7). A reagent-matched standard calibration curve was used for quantification of Hyp, with linear correlation coefficient (R~2) > 0.99 in the concentration range of 0.1-100 μg/mL. The LOQs were from 0.25 to 5 mg/kg, which were usually sufficient to verify the Hyp in samples. The confirmation concentration of Hyp ranged from 10 to 50 mg/kg.