title: Determination of chlorine via the CaCl molecule by high-resolution continuum source graphite furnace molecular absorption spectrometry and direct solid sample analysis.
abstract: This work investigates the possibilities of high-resolution continuum source graphite furnace molecular absorption spectrometry for the direct determination of Cl in solid samples via the CaCl molecule and measurement of its molecular absorption. The method proposed is based on addition of 400µg Ca as molecule-forming reagent and of 20µgPd as chemical modifier, which helps to stabilize the analyte and enhances sensitivity. The molecular spectrum for CaCl offers different lines with different limits of detection and linear ranges, which permitted to analyze solid samples with different Cl contents. The lowest limit of detection (0.75ng Cl, corresponding to 0.75µgg-1for a typical sample mass of 1mg) could be achieved by combination of three of the most sensitive lines in the vicinity of 620.862nm, while the amplest linear range (up to 860ng Cl) was achieved by selection of the less sensitive line at 377.501nm. The method developed enabled the direct determination of Cl in solid samples using simple external calibration with aqueous standards. Good precision (5-9% RSD) and accuracy was attained in a series of certified samples of very different nature (i.e. coal, iron oxide, polyethylene, human hair, pine needles, rice flour and milk) and with very different Cl contents, ranging from about 50µgg-1to 1% (w/w) Cl. The method appears as particularly useful for Cl determination in samples with elevated Ca contents, for which biased results with other diatomic molecules, such as AlCl or SrCl, may be obtained.
authors.affiliation: Department of Analytical Chemistry, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain; Department of Chemistry, Federal University of Santa Maria, C.P. 5051, 97105-970 Santa Maria - RS, Brazil.
authors.forename: Ananda
authors.initials: A
authors.lastname: Guarda
authors.affiliation: Department of Analytical Chemistry, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain; Centro Universitario de la Defensa de Zaragoza, Academia General Militar de Zaragoza, Carretera de Huesca s/n, 50090 Zaragoza, Spain.
authors.forename: Maite
authors.initials: M
authors.lastname: Aramendía
authors.affiliation: Department of Analytical Chemistry, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Andrés
authors.affiliation: Department of Analytical Chemistry, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: Esperanza
authors.initials: E
authors.lastname: García-Ruiz
authors.affiliation: Department of Chemistry, Federal University of Santa Maria, C.P. 5051, 97105-970 Santa Maria - RS, Brazil.
authors.forename: Paulo Cícero
authors.initials: PC
authors.lastname: do Nascimento
authors.affiliation: Department of Analytical Chemistry, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain. Electronic address: mresano@unizar.es.
authors.forename: Martín
authors.initials: M
authors.lastname: Resano
keywords: CaCl molecular absorption; Chlorine determination; High-resolution continuum source molecular absorption spectrometry; Solid sample analysis