Quantitative determination of DNA adducts using liquid chromatography/electrospray ionization mass spectrometry and liquid chromatography/high-resolution inductively coupled plasma mass spectrometry.
The quantitative determination of nucleotides from DNA modified by styrene oxide is described using a combination of inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) and electrospray ionization mass spectrometry (ESI-MS), both interfaced to reversed-phase high-performance liquid chromatography (HPLC). LC/ICP-MS (resolution > 1500 to discriminate against 15N16O+ and 14N16OH+) was employed to determine quantitatively the content of modified nucleotides in standard solutions based on the signal of phosphorus; phosphoric acid served as an internal standard. By means of the standard addition technique the sensitivity of the LC/ESI-MS approach was subsequently determined. Since a comparison of UV, ICP and ESI-MS data suggested that in ESI-MS the ionization efficiency of the adducts is identical within the error limits, quantitative determination of all adducts is possible. For LC/ESI-MS with single ion monitoring, the detection limit for styrene oxide adducts of nucleotides was determined to be 20 pg absolute or 14 modified in 10(8) unmodified nucleotides in a 5 micrograms DNA sample, which comes close to the best methods available for the detection of chemical modifications in DNA.
Siethoff
C
C
ISAS Institute of Spectrochemistry and Applied Spectroscopy, Dortmund, Germany.
Feldmann
I
I
Jakubowski
N
N
Linscheid
M
M
D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods; D018736:DNA Adducts / Q000032:analysis / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods
D018736:DNA Adducts