Title: Nuclear magnetic resonance at the picomole level of a DNA adduct.

Authors: Kautz, Roger; Wang, Poguang; Giese, Roger W

Published In Chem Res Toxicol, (2013 Oct 21)

Abstract: We investigate the limit of detection for obtaining NMR data of a DNA adduct using modern microscale NMR instrumentation, once the adduct has been isolated at the picomole level. Eighty nanograms (130 pmol) of a DNA adduct standard, N-(2'-deoxyguanosin-8-yl)-2-acetylaminofluorene 5'-monophosphate (AAF-dGMP), in 1.5 *L of DýýýO with 10% methanol-dýýý, in a vial, was completely picked up as a droplet suspended in a fluorocarbon liquid and loaded efficiently into a microcoil probe. This work demonstrates a practical manual method of droplet microfluidic sample loading, previously demonstrated using automated equipment, which provides a severalfold advantage over conventional flow injection. Eliminating dilution during injection and confining the sample to the observed volume produce the full theoretical mass sensitivity of a microcoil, comparable to that of a microcryo probe. With 80 ng, an NMR spectrum acquired over 40 h showed all of the resonances seen in a standard spectrum of AAF-dGMP, with a signal-to-noise ratio of at least 10, despite broadening due to previously noted effects of conformational exchange. Even with this broadening to 5 Hz, a two-dimensional total correlation spectroscopy spectrum was acquired on 1.6 *g in 18 h. This work helps to define the utility of NMR in combination with other analytical methods for the structural characterization of a small amount of a DNA adduct.

PubMed ID: 24028148

MeSH Terms: Automation; DNA Adducts/analysis*; DNA Adducts/standards; Fluorocarbons/chemistry; Magnetic Resonance Spectroscopy*/instrumentation; Magnetic Resonance Spectroscopy*/standards; Microfluidic Analytical Techniques; Reference Standards