Development of a quality control material for the measurement of 8-oxo-7,8-dihydro-2 '-deoxyguanosine, an in vivo marker of oxidative stress, and comparison of results from different laboratories

The measurement of 8-oxo-7,8-dihydro-2'-deoxyguanosine is an increasingly p opular marker of in vivo oxidative damage to DNA. A random-sequence 21-mer oligonucleotide 5'-TCA GXC GTA CGT GAT CTC AGT-3' in which X was 8-oxo-guan ine (8-oxo-G) was purified and accurate determination of the oxidised base was confirmed by a P-32-end labelling strategy. The lyophilised material wa s analysed for its absolute content of 8-oxo-dG by several major laboratori es in Europe and one in Japan. Most laboratories using HPLC-ECD underestima ted, while GC-MS-SIM overestimated the level of the lesion. HPLC-ECD measur ed the target value with greatest accuracy. The results also suggest that n one of the procedures can accurately quantitate levels of 1 in 10(6) 8-oxo- (d)G in DNA.