Quantifying Uncertainty of Calcium Determination in Infant Formula by AAS and ICP-AES

AAS 및 ICP-AES에 의한 조제분유 중 칼슘 함량 분석의 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 : 2004.10.31

Abstract

Uncertainty was quantified to evaluate calcium determination result in infant formula with AAS (Atomic Absorption Spectrometry) and ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). Uncertainty sources in measurand, such as sample weight, final volume of sample, sample dilution and the instrumental result were identified and used as parameters for combined standard uncertainty based on the GUM (Guide to the expression of uncertainty in measurement) and Draft EURACHEM/CITAC Guide. Uncertainty components of each sources in measurand were identified as resolution, reproducibility and stability of chemical balance, standard material purity, standard material molecular weight, standard solution concentration, standard solution dilution factor, sample dilution factor, calibration curve, recovery, instrumental precision, reproducibility, and stability, Each uncertainty components were evaluated by uncertainty types and included to calculate combined uncertainty. The kinds of uncertainty sources and components in the analytical method by AAS and ICP-AES were same except sample dilution factor for AAS. The analytical results and combined standard uncertainties of calcium content were estimated within the certification range $(367{\pm}20\;mg/100g)$ of CRM (Certified Reference Material) and were not significantly different between method by AAS followed by ashing and method by ICP-AES followed by acid digestion as $359.52{\pm}23.61\;mg/100g\;and\;354.75{\pm}16.16\;mg/100g$, respectively. Identifying uncertainty sources related with precision, repeatability, stability, and maintaining proper instrumental conditions as well as personal proficiency was needed to reduce analytical error.

Keywords

uncertainty;calcium;infant formula;AAS;ICP-AES

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