Clinical Chemistry, Vol 18, 1475-1477, Copyright © 1972 by the American Association for Clinical Chemistry

Manual Spectrophotometric and Fluorometric Determination of Tocopherol in Cerebrospinal Fluid

¹ Neurochemistry Laboratory, Neurology Service, VA Hospital, Minneapolis, Minn. 55417; and Departments of Biochemistry and Neurology, University of Minnesota, Minneapolis, Minn. 55455.

Methods are reported for the manual spectrophotometric or fluorometric estimation of tocopherol in human cerebrospinal fluid. The fluid is centrifuged, an equal volume of ethanol is added, and the tocopherol is extracted with hexane, which is then used for the direct estimation by fluorometry. The fluorescence of tocopherol is significantly affected by the proportion of ethanol in the hexane solvent. The standards used for comparison should therefore be dissolved in hexane that had been previously equilibrated with twice its volume of ethanol:water (1:1 by vol). For spectrophotometry, the original hexane extract is dried at 40°C under reduced pressure, the residue dissolved in hexane, and color developed by adding bathophenanthroline, ferric chloride, and orthophosphoric acid. The color is measured at 536 nm. Concentrations of tocopherol in the spinal fluid samples analyzed so far ranged from 40 to 210 µg/ liter.