Sensitive quantitation of chromium-DNA adducts by inductively coupled plasma mass spectrometry with a direct injection high-efficiency nebulizer

A novel method is described for the sensitive detection of chromium-DNA add ucts. Chromium-DNA adducts were determined in 1 mu g of DNA from normal hum an lung fibroblasts exposed to sodium chromate using microscale flow inject ion analysis with a direct injection high-efficiency nebulizer and inductiv ely coupled plasma mass spectrometry detection. The frequency of Cr-DNA add ucts increased in a dose-dependent sigmoidal manner, indicating saturation and toxicity. The low detection limits (on the order of parts per trillion) allows the detection of as few as two Cr adducts per 10,000 bases, which, coupled with the small DNA sample requirement, makes this technique suitabl e for measuring metal-DNA adducts as biomarkers of exposure to toxic and ca rcinogenic metals such as Cr, in cultured cells, animals, and humans. (C) s ociety of Toxicology.