ANALYSIS OF THE MALONDIALDEHYDE-2'-DEOXYGUANOSINE ADDUCT PYRIMIDOPURINONE IN HUMAN-LEUKOCYTE DNA BY GAS-CHROMATOGRAPHY ELECTRON-CAPTURE NEGATIVE CHEMICAL-IONIZATION MASS-SPECTROMETRY

A method is described for the assay of the major malondialdehyde-deoxy guanosine adduct (M(1)G) based on immunoaffinity purification and gas chromatography/electron capture/negative chemical ionization/mass spec trometry. A stable isotope of M(1)G-deoxyribose ([H-2(2)]M(1)G-dR) was used as an internal standard. Recovery of internal standard throughou t the entire assay procedure was similar to 40%. The assay showed a li near response over a range of 10-1000 pg of M(1)G-dR and was verified by analysis of a synthetic, M(1)G-containing oligomer. The limit of de tection in biological samples was 100 fmol/sample, corresponding to 3 adducts/10(8) bases for 1 mg of DNA. DNA was isolated from the blood o f 10 healthy human donors, and M(1)G levels were measured. A mean valu e of 6.2 +/- 1.2 adducts/10(8) bases was obtained, with no obvious dif ferences based on age or cigarette smoking. A small, but statistically significant difference was observed between the levels in females (5. 1 +/- 0.4 adducts/10(8) bases) and males (6.7 +/- 1.1 adducts/10(8) ba ses). The presence of M(1)G in leukocyte DNA was further verified by a nalysis using liquid chromatography/electrospray ionization mass spect rometry.