Measurement of a-, j3-, and ‘y-Tocopherol in Serum by Liquid Chromatography

A liquid-.chromatographic assay for a-, f3-,and y-isomeric tocopherolsinhuman serum isreported.The tocopherols and the internal standard (tocol) are adsorbed onto a silica gelcolumn and are eluted in less than 10 mm with n-hex-ane/isopropanol (99.4/0.6, by vol)at a flow rate of 1 mL/min. The complete analysis requires no longer than 30 mm. Within-day precision (CV) was 1.4 % ( = 13.18 mg/L, n = 24), 7.4 % ( = 0.214 mg/L, n = 14), and 1.3% (x = 1.01 mg/L, n = 14) for a-, 3-, and y-tocopherol, re-spectively. Day-to-day precision (CV) was 4.4 % ( = 9.85 mg/L, n = 10) for a-tocopherol, 9.1 % ( = 0.222 mg/L, n = 20) forfl-tocopherol, and 3.8 % ( = 1.00 mg/L, n = 20)fory-tocopherol.Extraction recoveries for a-, /3-, and y-tocopherol averaged 92.4 ± 2.9 % (n = 5),91.4 ± 7.6% (n = 5), and 92.0 ± 4.1 % (n = 4), respectively. Th