[Research on pretreatment methods for cystine determination in milk powder].

Objective: To establish a rapid, accurate and safe pretreatment method for the determination of cystine in milk powder.

Methods: Samples were oxidized at 50 ℃ for 10 min after adding performic acid, and then the reaction was terminated with ethanol as oxidation terminator. The reaction solution was concentrate to dryness by vacuum centrifugation at 50 ℃.