Analysis of thiamine in milk by gas chromatography and the nitrogen-phosphorus detector.

Free thiamine and total thiamine in milk were analyzed by gas chromatography using a nitrogen-phosphorus detector. Sodium bisulfite was used to cleave thiamine into 4-methyl-5-(2-hydroxyethyl)thiazole, which can be extracted by chloroform. The procedure was simplified by the use of 3-(3-pyridyl)-1-propanol as an internal standard. Free thiamine was determined by cleaving the thiamine before reacting it with an enzyme that removes phosphate and allows for the quantitation of total thiamine. The validity of the procedure was demonstrated by analysis of homogenized, nonfat dry, and raw whole milk. Thiamine is reported in microgram/100 ml.