title: Limits of detection of a total reflection X-ray fluorescence system with double reflection module.
abstract: An X-ray tube with a Mo target and Zr filter, operated at 45 kV/20 mA, was used to excite samples (5 microL deposited on a quartz support) and the total reflection angle condition was obtained with a double reflector module built with two 10-cm-long 7-mm-thick quartz crystals placed 50 microns apart. A high-resolution spectrometer based on a Si(Li) detector coupled to a multichannel analyzer was used for X-ray detection and the spectra were interpreted with the AXIL software. The system was calibrated with standard chemical solutions containing Cr, Fe, Cu, Zn, and Pb, and Y was used as an internal standard to correct eventual geometric errors and high-voltage instabilities of the X-ray generator. The limits of detection were 19, 9, 5, and 4 ng/mL for Cr, Fe, Cu, and Zn, respectively, analyzed through characteristic K alpha X-rays, and 7 ng/mL for Pb, through L alpha X-rays, considering 50 microL samples deposited and dried on a quartz support, to be excited/detected for 1000 s.
authors.affiliation: Laboratório de Instrumentação Nuclear/CENA/USP, Piracicaba, Brazil.
authors.forename: V F
authors.initials: VF
authors.lastname: Nascimento Filho
authors.forename: V H
authors.initials: VH
authors.lastname: Poblete
authors.forename: P S
authors.initials: PS
authors.lastname: Parreira
authors.forename: E
authors.initials: E
authors.lastname: Matsumoto
authors.forename: S M
authors.initials: SM
authors.lastname: Simabuco
authors.forename: E P
authors.initials: EP
authors.lastname: Espinoza
authors.forename: A A
authors.initials: AA
authors.lastname: Navarro
mesh_terms: D002138:Calibration; D012680:Sensitivity and Specificity; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation / Q000379:methods*; D014131:Trace Elements / Q000032:analysis*
chemical_list: D014131:Trace Elements