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KMID : 0380620080400020152
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Korean Journal of Food Science and Technology
2008 Volume.40 No. 2 p.152 ~ p.159
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Chemistry/Analysis : A Comparative Study on Quantifying Uncertainty of Vitamin A Determination in Infant Formula by HPLC
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Lee Hong-Min
Kwak Byung-Man
Ahn Jang-Hyuk
Jeon Tae-Hong
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Abstract
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The purpose of this study was to determine the accurate quantification of vitamin A in infant formula by comparing two different standard stock solutions as well as various sample weights using high performance liquid chromatography. The sources of uncertainty in measurement, such as sample weight, final smaple vloume, and the instrumental results, were identified and used as parameters to determine the combined standard uncertainty based on GUM(guide to the expression of uncertainty in measurement) and the Draft EURACHEM/CITAC Guide. The uncertainty components in measuring were identified as standard weight, purity, molecular weight, dilution of the standard solution, calibration curve, recovery, reproducibility, sample weight, and final sample volume. Each uncertainty component was evaluated for type A and type B and included to calculate the combined uncertainty. The analytical results and combined standard uncertainties of vitamin A according to the two different methods of stock solution preparation were 627 ± 33 μg R.E./100 g for 1,000 mg/L of stock solution, and 627 ± 49 μg R.E./100 g for 100 mg/L of stock solution. The analytical results and combined standard uncertainties of vitamin A according to the various sample weighs were 622 ± 48 μg R.E./ 100 g, 627 ± 33 μg R.E./100 g, and 491 ± 23 μg R.E./100 g for 1 g, 2 g, and 5 g of sampling, respectively. These data indicate that the preparation method of standard stock solution and the smaple amount were main sources of uncertainty in the analysis results for vitamin A. Preparing 1,000 mg/L of stock solution for standard material sampling rather than 100 mg, and sampling not more than 2 g of infant formula, would be effective for reducing differences in the results as well as uncertainty.
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KEYWORD
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uncertainty, vitamin A, retinol, infant formula, HPLC
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