Determination of 8-oxoguanine in human plasma and urine by high-performance liquid chromatography with electrochemical detection.
A highly sensitive and selective method for determining 8-oxoguanine in plasma and urine was developed by high-performance liquid chromatography with electrochemical detection. The compound was separated by gradient elution on a C18 reversed-phase column with a mobile phase of acetonitrile and 0.1 M sodium acetate, pH 5.2. 8-Hydroxy-2'-deoxyguanosine was used as internal standard. 8-Oxoguanine was detected electrochemically by setting the potential to +300 mV vs. Pd reference. The sensitivity of the assay was 22 ng/ml with a signal-to-noise ratio of 7:1. The within-day relative standard deviations for 8-oxoguanine quality control samples with concentrations of 3340, 1340 and 84 ng/ml were 3.6, 4.3 and 5.7% for plasma, and 4.1, 4.6 and 6.2% for urine, respectively. The day-to-day relative standard deviations for the same samples were 3.8, 6.8 and 7.1% for plasma, and 3.9, 7.0 and 7.9% for urine, respectively. The method is designed to study the pharmacokinetics and metabolic fate of O6-benzylguanine in a phase I clinical trial. Previously, O6-benzyl-8-oxoguanine was identified as the primary metabolite of O6-benzylguanine in humans. We now demonstrate that 8-oxoguanine is a further metabolite of O6-benzylguanine.
Long
L
L
Section of Hematology-Oncology, University of Chicago, IL 60637, USA.
McCabe
D R
DR
Dolan
M E
ME
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004563:Electrochemistry; D006147:Guanine / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
C024829:8-hydroxyguanine; D006147:Guanine