关键词: 乳粉；反相高效液相色谱法；6S-5-甲基四氢叶酸钙；三氯乙酸；抗坏血酸

Abstract: A reversed-phase high performance liquid chromatography (RP-HPLC) method was established for the determination of 6S-5-methyltetrahydrofolate calcium in milk powder. After protein precipitation with trichloroacetic acid solution, samples were extracted with ascorbic acid solution in a hot water bath, and the extract was separated on a C18 reversed-phase column by gradient elution using a mobile phase composed of 0.1% trifluoroacetic acid solution and methanol, and the detection wavelength was set at 280 nm. Quantitative analysis was carried out by the single standard method. The results showed that the limit of quantification and detection of 6S-5-methyltetrahydrofolate calcium in milk powder samples were 150 and 50 μg/100 g, respectively. The recoveries for samples spiked at levels ranging from 150 to 600 μg/100 g were 95.0%–109.1% with relative standard deviations (RSDs) between 1.26% and 4.04%. This method is simple, accurate, with high recovery and reproducibility, and suitable for the determination of 6S-5-methyltetrahydrofolate calcium in milk powder.

Key words: milk powder; reversed-phase high performance liquid chromatography; 6S-5-methyltetrahydrofolate calcium; trichloroacetic acid; ascorbic acid