Quantifying Uncertainty of Vitamin C Determination in Infant Formula by Indophenol Titration Method

인도페놀 적정법에 의한 성장기용조제식 중 비타민 C 함량분석의 측정불확도 산정

  • Jun, Jang-Young (Research and Development Center, Namyang Dairy Products Corporation) ;
  • Kwak, Byung-Man (Research and Development Center, Namyang Dairy Products Corporation) ;
  • Ahn, Jang-Hyuk (Research and Development Center, Namyang Dairy Products Corporation) ;
  • Kong, Un-Young (Research and Development Center, Namyang Dairy Products Corporation)
  • 전장영 (남양유업(주) 중앙연구소) ;
  • 곽병만 (남양유업(주) 중앙연구소) ;
  • 안장혁 (남양유업(주) 중앙연구소) ;
  • 공운영 (남양유업(주) 중앙연구소)
  • Published : 2005.06.30

Abstract

Uncertainty involved during determination of vitamin C content in infant formula was quantified by indophenol titration method. Uncertainty sources in measurand, such as purity, weight, final volume of standard, volume of standard solution used for titration, sample weight, final volume of sample, extraction solution used for titration, titration of extraction solution and standard solution by indophenol solution were identified and used as parameters for combined standard uncertainty based on Guide to the expression of uncertainty in measurement (GUM) and Draft EURACHEM/CITAC Guide. Uncertainty parameters of each source in measurand were identified as resolution, reproducibility and stability of chemical balance, standard material purity, repeatability, reproducibility, end point of titration, 1 mL pipet, 5 mL autopipet, and 100 mL mass flask. Each uncertainty component was evaluated by types A and B and included to calculate combined uncertainty. Analytical test result for traceability under laboratorial conditions using Certified Reference Material (CRM) test was certified as $108.4{\pm}1.7mg/100g$, which was within CRM certification range of $114.6{\pm}6.6mg/100g$. Uncertainty test result of vitamin C content of 5 g sampling was $56.7{\pm}2.44mg/100g$. Uncertainty could be reduced by identification of uncertainty sources and components related with vitamin C determination by indophenol titration method and by decreasing uncertainty sources and components.

Keywords

uncertainty;infant formula;vitamin C;indophenol

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