The determination of 2,6-diamino-9-(2-hydroxyethoxymethyl)-9H-purine (A134U) and 2-amino-9-(2-hydroxyethoxymethyl)-9H-purine (A515U) in human plasma and urine by gas chromatography

Summary

A novel, sensitive and selective automated method for the analysis of low concentrations of A134U and A515U in human plasma and urine has been developed. It involved extraction of the drugs (with an internal standard) from urine or plasma and conversion to trimethylsilyl derivatives. The trimethylsilylated extract was then chromatographed using a temperature programmed injection cycle on a gas chromatographic column packed with 5% OV17 on Chromosorb W-HP. Components were detected by an alkaline flame-ionisation detector. BASIC computation capability was utilised for both control of the autosampler and calculation of the results using a linear regression calibration of the standards used. Automation allowed 48 injections per 24 hours. Samples were routinely assayed in duplicate with a range of spiked standards and a control sample.

The assay was linear for plasma and urine in the range 0.5–200 µM with no interference from acyclovir, known metabolites, endogenous compounds, or a specific inhibitor [erythro-9-(2-hydroxy-2-nonyl) adenine (EHNA)]. The method had a sensitivity of less than 0.5µM. It has been applied successfully to clinical studies.