Internal standardization and least-squares background correction in high-resolution continuum source flame atomic absorption spectrometry to eliminate interferences on determination of Pb in phosphoric acid |
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Authors: | Jorge L Raposo Jr Silvana R Oliveira Joaquim A Nóbrega José A Gomes Neto |
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Institution: | 1. São Paulo State University, UNESP, Institute of Chemistry, Analytical Chemistry Department, P.O. Box 355, 14801-970 Araraquara — SP, Brazil;2. Universidade Federal de São Carlos, Departamento de Química, 13560-970 São Carlos — SP, Brazil |
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Abstract: | In this work the least-squares background correction (LSBC) and internal standardization (IS) techniques were combined to eliminate spectral and transport interferences in the determination of Pb in phosphoric acid by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). Blanks, samples and reference solutions 0.10–1.00 mg L− 1 Pb in 1% (v/v) HNO3] were spiked with 4.00 mg L− 1 Co used as internal standard. For absorbance measurements at the wavelength integrated absorbance equivalent to 9 pixels, correlations between the ratio of absorbance of Pb to absorbance of Co and the analyte concentration were close to 0.9992. Relative standard deviations of measurements varied from 0.6 to 4% and 1 to 7% (n = 12) without and with IS/LSBC techniques, respectively. Recoveries for Pb spikes were in the 96–104% and 76–180% range with and without IS/LSBC, respectively. The limit of detection improved with IS/LSBC techniques. Accuracy of the proposed method was checked for the determinations of Pb in commercial phosphoric acid samples and results obtained with IS were better than those without IS. |
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Keywords: | Lead Phosphoric acid Least Least-squares background correction Internal standardization High-resolution continuum source atomic absorption spectrometry |
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