title: Multivariate optimization and simultaneous determination of hydride and non-hydride-forming elements in samples of a wide pH range using dual-mode sample introduction with plasma techniques: application on leachates from cement mortar material.
abstract: Analytical methods have been developed for the simultaneous determination of hydride-forming (As, Sb) and non-hydride-forming (Cr, Mo, V) elements in aqueous samples of a wide pH range (pH 3-13). The methods used dual-mode (DM) sample introduction with ICP-AES and ICP-MS instruments. The effect of selected experimental variables, i.e., sample pH and concentrations of HNO(3), thiourea, and NaBH(4), were studied in a multivariate way using face-centered central composite design (FC-CCD). Compromised optimum values of the experimental parameters were identified using a response optimizer. The statistically found optimum values were verified experimentally. The methods provided improved sensitivities for the hydride-forming elements compared with the respective conventional nebulization (Neb) systems by factors of 67 (As) and 64 (Sb) for ICP-AES and 36 (As) and 54 (Sb) for ICP-MS. Slight sensitivity improvements were also observed for the non-hydride-forming elements. The limits of detection (LOD) of As and Sb were lowered, respectively, to 0.8 and 0.9 microg L(-1) with the DM-ICP-AES system and to 0.01 and 0.02 microg L(-1) with the DM-ICP-MS system. The short-term stabilities of both methods were between 2.1 and 5.4%. The methods were applied for the analysis of leachates of a cement mortar material prepared in the pH range 3-13. The elemental concentration of the leachates determined by the two DM methods were statistically compared with the values obtained from Neb-ICP-MS analysis; the values showed good agreement at the 95% confidence level. Quantitative spike recoveries were obtained for the analytes from most of the leachates using both DM methods.
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315, Oslo, Norway.
authors.forename: Mesay
authors.initials: M
authors.lastname: Mulugeta
authors.forename: Grethe
authors.initials: G
authors.lastname: Wibetoe
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Engelsen
authors.forename: Alemayehu
authors.initials: A
authors.lastname: Asfaw
mesh_terms: D000965:Antimony / Q000032:analysis*; D001151:Arsenic / Q000032:analysis*; D003252:Construction Materials / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D019216:Metals, Heavy / Q000032:analysis*; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013054:Spectrophotometry, Atomic
chemical_list: D019216:Metals, Heavy; D000965:Antimony; D001151:Arsenic