title: FemtoMolar measurements using accelerator mass spectrometry.
abstract: Accelerator mass spectrometry (AMS) is an ultra-sensitive analytical method suitable for the detection of sub-nM concentrations of labeled biological substances such as pharmaceutical drugs in body fluids. A limiting factor in extending the concentration measurements to the sub-pM range is the natural (14)C content in living tissues. This was circumvented by separating the labeled drug from the tissue matrix, using standard high-performance liquid chromatography (HPLC) procedures. As the separated total drug amount is in the few fg range, it is not possible to use a standard AMS sample preparation method, where mg sizes are required. We have utilized a sensitive carbon carrier method where a (14)C-deficient compound is added to the HPLC fractions and the composite sample is prepared and analyzed by AMS. Using 50 microL human blood plasma aliquots, we have demonstrated concentration measurements below 20 fM, containing sub-amol amounts of the labeled drug. The method has the immediate potential of operating in the sub-fM region.
authors.affiliation: Ion Physics, Angström Laboratory, Department of Engineering Sciences, Box 534, Uppsala University, SE-751 21 Uppsala, Sweden. mehran.salehpour@teknik.uu.se
authors.forename: Mehran
authors.initials: M
authors.lastname: Salehpour
authors.forename: Niklas
authors.initials: N
authors.lastname: Forsgard
authors.forename: Göran
authors.initials: G
authors.lastname: Possnert
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D002250:Carbon Radioisotopes / Q000032:analysis; D007553:Isotope Labeling / Q000379:methods; D008832:Microchemistry / Q000379:methods*; D050997:Nanomedicine / Q000379:methods*; D010315:Particle Accelerators; D017330:Remoxipride / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D002250:Carbon Radioisotopes; D017330:Remoxipride