Objective To develop an ion chromatography method for the determination of protein in raw milk.Method The proteins in raw milk were precipitated by 15% trichloroacetic acid and then filtered.The raw milk and the filtrate were digested separately by a H_2SO_4-H_2O_2 system.The eluent was 20 mmol/L methanesulfonic acid.The analytical column was Ionpac CS12A and the NH+_4-N content was detected by DS-6 conductivity detector.The protein content in raw milk was calculated by the difference between the NH+_4-N co...