Comparison between capillary and nano liquid chromatography-electrospray mass spectrometry for the analysis of minor DNA-melphalan adducts

Nano liquid chromatography (nanoLC) coupled to electrospray mass spectromet ry (ES-MS) was evaluated for the analysis of DNA adducts in melphalan-treat ed Jurkat cells. The detection limit of the nanoLC-ES-MS-MS system was asse ssed using a dAMP-melphalan adduct. Compared to capillary liquid chromatogr aphy (capLC) ES-MS the absolute detection limit could be improved by a fact or 10, leading to the detection of 395 fg dAMP-melphalan adduct under singl e-ion monitoring conditions at a S/N of 14. Minor adducts such as cross-lin ked adducts could be detected in in vitro solutions of 2'-deoxynucleotides (dNMP) treated with melphalan using column-switching nanoLC-ES-MS. These ad ducts were not found using capLC-ES-MS. More detailed structural informatio n of the alkylation sites was obtained by examining the nanoLC-ES-MS-MS dat a. Jurkat cells were treated with melphalan, the modified DNA was isolated and enzymatically hydrolyzed. Several modified dinucleotides were identifie d, the most abundant adducts were pdG(Mel(Cl))pdC (m/z=453, t(r)=17.0 min) and pdG(Mel(OH)) pdC ring opened (m/z=453, t(r)=39.5 min). (C) 2000 Elsevie r Science BN. All rights reserved.