Improved liquid chromatographic assay for the analysis of pirmenol in plasma and urine

A sensitive, specific, and rapid high-performance liquid chromatographic procedure was developed for the determination of pirmenol in human biological fluids. Plasma or urine samples were alkalinized and extracted with cyclohexane. The organic extract was evaporated to dryness, reconstituted with the mobile phase, and then chromatographed on a microparticulate spherical trimethylsilane stationary phase with UV detection at 254 nm. The procedure for the assay of pirmenol in plasma was linear from 0.125 to 5.0 micrograms/mL. The reproducibility of the peak area ratios of the standard curves had relative standard deviations between 7.7 and 1.8% and a relative error of 0-4.6% over the linear range. The accuracy for the determination of pirmenol in human plasma containing 0.5, 2.5, and 4.0 micrograms/mL had relative errors of 9.0, 3.8, and 3.6%, respectively. Thirty compounds were tested and found not to interfere in the assay of the drug in plasma, and the method was found to be suitable for clinical samples. The urine procedure was linear between 1.0 and 30.0 micrograms/mL. The reproducibility of the peak areas of the standard curves had relative standard deviations that ranged from 1.9 to 6.2% over the linear range. The accuracy for the determination of pirmenol in human urine containing 5.0, 17.5, and 25.0 micrograms/mL had relative errors of 1.4, 0.5, and 2.8%, respectively.