Analysis of tamoxifen-induced DNA adducts by 32P-postlabelling assay using different chromatographic techniques

DNA isolated from livers of rats receiving tamoxifen was analysed by the 32P-postlabelling method. The postlabelled DNA hydrolysis mixture was analysed both by reversed-phase HPLC with 32P on-line detection and by TLC on polyethyleneimine plates followed by autoradiography. Using the HPLC method, five well separated adduct peaks could be detected, while by the TLC method, two groups of adduct spots were observed. The detection limit of the TLC assay was lower (0.5 adducts/10(10) nucleotides) than that of the HPLC assay (3 adducts/10(10) nucleotides). Thus, the TLC assay is more sensitive but also more laborious. The advantages of the HPLC assay were, in addition to better resolution, the ease of quantification and operation.