title: Quantitative analysis of small molecules by desorption electrospray ionization mass spectrometry from polytetrafluoroethylene surfaces.
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.
authors.affiliation: Department of Chemistry, Purdue University, Bindley Biosciences Center, West Lafayette, IN 47907, USA.
authors.forename: Demian R
authors.initials: DR
authors.lastname: Ifa
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Manicke
authors.forename: Allison L
authors.initials: AL
authors.lastname: Rusine
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D000327:Adsorption; D008970:Molecular Weight; D004364:Pharmaceutical Preparations / Q000032:analysis*; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013499:Surface Properties
chemical_list: D004364:Pharmaceutical Preparations; D011138:Polytetrafluoroethylene