Development of an Analytical Method Based in the Slurry Sampling for Iron Determination in Fortified Milk Powder by HR-CS FAAS |
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Authors: | Geovani Cardoso Brandao Dalita Pedrosa Gomes and Geraldo Domingues Matos |
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Affiliation: | (1) Universidade Federal da Bahia, Instituto de Qu?mica, Campus Ondina, Salvador, Bahia, 40170-290, Brazil |
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Abstract: | The use of slurry sampling as the procedure for sample preparation provides simplicity, speed, and low consumption of reagents
in analytical methods. In this paper, a method based on slurry sampling for the determination of iron in samples of fortified
milk powder by high-resolution continuum source flame atomic absorption spectrometry was developed. Multivariate design techniques
were applied for the optimization of experimental conditions of the method for a sample mass of 100 mg, final volume of slurry
of 10 mL, and using the absorbance signal as response. Initially, a two-level full factorial design was used for the preliminary
evaluation of the variables involved in slurry preparation: concentration hydrochloric acid, Triton X-100 concentration, and
sonication time. Then, the Doehlert matrix was applied for the determination of the critical conditions: 2.5 mol L−1 hydrochloric acid and sonication time of 20 min. External calibration technique with aqueous standard was used for the quantification
of iron. This way, the method allowed iron determination with limits of detection and quantification of 0.9 and 3.0 μg g−1, respectively. The precision expressed as the relative standard deviation was evaluated under repeatability and reproducibility
conditions, being 3.2% and 4.0%, respectively. Addition/recovery test was used for assessing the accuracy of the method, and
the recovery values achieved were in the range of 90–110%. The method was applied for iron determination in eight samples
of fortified milk powder, and the obtained concentrations varied from 95.4 to 295.6 μg g−1. The results were compared with those obtained after acid digestion, and no significant difference was observed applying
t test at the 95% confidence level. |
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