Improved method for selenium determination in biological samples by gas chromatography

A gas chromatographic assay employing electron-capture detection for the determination of selenium in biological samples is reported. A calibration curve of 4-nitro-o-phenylene-diamine derivative of selenium as a function of peak area was linear from 5-1000 pg. The limit of detection for the electron-capture detector was approximately 0.5 pg. Recoveries of selenium added to various biological materials ranged from 95-105%. This procedure reduces the number of transfers thereby reducing errors associated with losses or contamination. One advantage of the present method is that interfering compounds occurring in previously employed chromatographic methods are eliminated. This procedure can be used for routine microanalysis of selenium. Samples containing less than 2 ng selenium in 200 microliter of biological fluid can be routinely analyzed using this method.