Automated fluorometric determination of vitamin A in milk

• Published in: Journal of the Association of Official Analytical Chemists Vol. 61; no. 6; p. 1370
• Main Authors: Thompson, J N, Madère, R
• Format: Journal Article
• Language: English
• Published: United States 01-11-1978
• Subjects: Animals; Autoanalysis; Cattle; Colorimetry; Humans; Milk - analysis; Spectrometry, Fluorescence - methods; Vitamin A - analysis
• ISSN: 0004-5756
• DOI: 10.1093/jaoac/61.6.1370

A previously published fluorometric method for vitamin A in milk, involving saponification in centrifuge tubes and extraction with hexane, was automated using conventional automated equipment including a filter fluorometer. The extraction and separation steps were affected by the presence of fat, so standards were prepared in milk. The peaks obtained with samples were 95% of steady state values. The coefficients of variation for 10 replicate analyses were 1.9% for unfortified milk and 1.3% for fortified milk. In tests on 19 different milk samples, the results of the automated and manual fluorometric methods differed by less than 10%; a colorimetric method using SbCl3 gave more erratic results and was more lengthy and laborious.