Abstract: When GB 5413.38-2016 national standard method is used to determine the freezing point of raw-milk,the quality control of the preparation of the freezing point calibration solution (standard solution A and standard solution B) is implemented,so that the precision and stability of the freezing point calibration solution meet the requirements of the standard.The experimental results showed that the precision of the calibration solution prepared with 99.90% high purity sodium chloride is less than ±1.0 m℃. Stored at (5±1) ℃ for 73 days,the deviation of freezing point values of freezing point calibration solution (standard solution A and standard solution B) from the theoretical value was less than ±2.0 m℃,meeting the needs of laboratory testing.

Key words: raw-milk freezing point instrument, calibration solution, preparation method