Pentafluorophenyldimethylsilylchloride (flophemesyl chloride, FICI) has recently been used for derivatizations of alcohols, leading to significant improvements in detectability by gas chromatography (GC)-photoionization detection (PID) and electron capture detection (ECD). This off-line reaction has now been applied to a number of related alcohol derivatives, naturally occurring bioorganics such as cholesterol, androsterone, and similar sterols and steroids. Standard GC-ECD-PID analytical parameters have been determined, such as detection limits, calibration plots, ECD and PID relative response factors (RRF), ECD/PID relative response factor ratios, etc. for underivatized and derivatized substrates. Packed and capillary column GC conditions have been used with a 10.2 eV PID lamp. Application of the optimized derivatization-GC-ECD-PID method is reported for bioorganics in biological media. The overall results demonstrate the immediate applicability of such an approach for a number of alcohol derivatives, especially those having biological properties.