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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

In situ digestion for the determination of Ca in beverages by tungsten coil atomic emission spectrometry

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Author(s):
Santos, Luana N. [1] ; Gonzalez, Mario H. [1] ; Moura, Monise F. [1] ; Donati, George L. [1] ; Nobrega, Joaquim A. [1]
Total Authors: 5
Affiliation:
[1] Univ Fed Sao Carlos, Dept Chem, Grp Appl Instrumental Anal, BR-13560 Sao Carlos, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Talanta; v. 97, p. 285-290, AUG 15 2012.
Web of Science Citations: 7
Abstract

Tungsten coil atomic emission spectrometry (WCAES) is employed for the determination of calcium in juice, mineral and coconut water samples. A sample aliquot of 20 mu L is placed directly on the coil and a constant-voltage power source is used to dry and atomize the sample, as well as to promote Ca atomic emission. Analytical signals are resolved and detected using a Czerny-Turner spectrometer and a charge coupled device detector. Some experimental parameters such as coil position related to the spectrometer entrance slit and integration time are critically evaluated. A heating program with relatively constant drying temperatures is used in all measurements. An in situ digestion procedure is used to partially decompose organic matrices and improve WCAES precision and accuracy. By adding an oxidizing mixture to the sample and including a digestion step in the heating cycle, no statistical difference was observed between WCAES and ICP OES results for Ca in juice and coconut water samples. Mineral water samples were simply diluted with 1% v v(-1) HNO3 before analysis and no significant interference was observed for concomitants such as Na and K. Despite severe positive interference caused by Mg, good agreement was obtained between WCAES and ICP OES results for Ca in several mineral water samples. Limits of detection and quantification obtained were 0.02 and 0.07 mg L-1, respectively. The method precision, calculated as the relative standard deviation for 10 consecutive measurements of a 2.5 mg L-1 Ca solution, is 3.8%. (C) 2012 Elsevier B.V. All rights reserved. (AU)