Analysis of 2-chloro-2'-deoxyadenosine in human blood plasma and urine by high-performance liquid chromatography using solid-phase extraction.

A reversed-phase high-performance liquid chromatographic (HPLC) method for the simultaneous determination of a new and promising anticancer drug, 2-chloro-2'-deoxyadenosine (CdA), and its metabolite, 2-chloroadenine (CAde), in plasma and urine was developed. A solid-phase extraction procedure with guaneran as internal standard (IS) was used. Plasma (1 ml) or diluted urine (1/100) mixed with 1 ml of phosphate buffer (10 mM, pH 6.5) was applied on a C8 isolute cartridge, which was prewashed with acetonitrile and phosphate buffer. The cartridge was further washed with 2.5 ml of 1% acetonitrile/phosphate buffer and 2.5 ml of hexane/dichloromethane (50/50). The compounds were eluted from the cartridge with 2.5 ml 5% MeOH in ethyl acetate. Chromatographic separation was achieved on C18 column eluted isocratically with phosphate buffer (10 mM, pH 3.0) containing 11% MeOH and 7% acetonitrile, and ultraviolet (UV) detection at 265 nm. Recoveries of CdA and CAde at 100 nmol/L were 90.6 +/- 4.9 and 98.7 +/- 7.8%, respectively. Recovery of IS was 96.1 +/- 6.1% at 250 nmol/l. The inter- and intraday coefficients of variation (CV) were < 10% at different concentrations within the range 1-500 nmol/L for both substances. In plasma, limits of detection of CdA and CAde were 1 and 2 nmol/L, respectively. In urine, the limit of detection was 100 nmol/L for both compounds. Standard curves were linear up to 50 and 500 nmol/L for urine and plasma, respectively. The present method will be a useful tool for further investigations of the pharmacokinetics of CdA in patients treated with different routes of administration.