Abstract
The complexations of cadmium ion with guanine bases were detected by electrospray ionization mass spectrometry (ESIโMS). In order to explore the toxicity of cadmium, such as oxidative stress to DNA and carcinogenesis, it is very important to determine the interactions between the cadmium ion and nucleotide. The analysis of mixed cadmium ionโguanosine aqueous solution (molar ratio 1 : 9) using ESIโMS (cone voltage 20 V) showed the presence of various cadmium complex ions, such as [n (guanosine) + Cd]^2+^ (n = 3โ8), [2guanine + Cd]^2+^, [guanosine + guanine + Cd]^2+^ and [guanosine + 2guanine + Cd]^2+^. The observed [2guanine + Cd]^2+^, [guanosine + guanine + Cd]^2+^ and [guanosine + guanine + Cd]^2+^ ions are formed through the dissociation of the Nโglycoside bond at the interface of ESIโMS. For deoxyguanosine and ethylguanine, similar cadmium complexes were observed. However, the complexes between the cadmium ion and 8โhydroxydeoxyguanosine were not detected. Furthermore, when a higher molar ratio (Cd : guanosine) or cone voltage were used, more of the monovalent ion peaks, such as [Cd(guanine โ H)~2~ + H]^+^ and [Cd(guanosine โ H)~2~ + H]^+^, were observed and a decrease in the abundance of the divalent ions, such as [n(guanosine)+Cd]^2+^, occurred. Copyright ยฉ 2003 John Wiley & Sons, Ltd.