Author(s): Ifa DR, Manicke NE, Rusine AL, Cooks RG
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Abstract Desorption electrospray ionization mass spectrometry (DESI-MS) is an emerging technique for ambient analysis. However, its application to routine quantitation has not been explored extensively and this is undertaken here. We present studies that utilize a particularly suitable surface, porous polytetrafluoroethylene (porous PTFE), which shows less cross contamination between samples and improved sensitivity and signal stability compared to other surfaces. Quantitative experiments for 1 microL spotted solutions of the beta-blocker propranolol, using isotopically labeled propranolol as internal standard, showed a good linear correlation (r2 > 0.996) over the range 0.01-100 microM. The inter-day precision, based on the relative standard deviation, for replicates analyzed on three different days was 13\% for 0.01 microM and better than 7\% for the remainder of the calibration points. The inter-day accuracy, expressed as relative error, was better than +/-7\% for all calibration points along the curve. These day-to-day measurements suggest that DESI-MS can be successfully employed for routine quantitative analysis. The use of the analog atenolol as an internal standard and further considerations that should improve quantitation by DESI-MS are also presented.
This article was published in Rapid Commun Mass Spectrom
and referenced in Journal of Analytical & Bioanalytical Techniques