Rapid Gas Chromatographic Method for Quantitation of Ethchlorvynol ("Placidyl") in Serum

A rapid, simple, and sensitive method for quantitation of ethchlorvynol by gas chromatography has been developed. Instrument response is linear to a concentration of 200 mg/liter (2.0-ml sample of serum). Day-to-day (20 days) precision of a 15 mg/liter serum pool was 0.85 mg/liter (SD) and 5.6% (CV). For 30 samples analyzed by both the gas chromatographic method and a colorimetric method, the correlation plot had a slope of 0.989, x and y intercepts near zero, and a correlation coefficient of 0.997. Mean recovery of ethchlorvynol added to serum was 87%. Subsequently, all standards were prepared in serum, to compensate for the nonquantitative yield and to help assure accuracy. Sera from healthy controls and from hospitalized patients contain no endogenous interfering substances, nor did any of a series of commonly prescribed drugs interfere.