ESTIMATION OF MEASUREMENT UNCERTAINTY: A CASE STUDY FOR DETERMINATION OF CALCIUM (CA) CONTENT IN POWDERED TONIC FOOD DRINK USING ION CHROMATOGRAPHY

Abstract

In participation of the laboratory on Proficiency Testing Scheme: Analysis of Proximates (Moisture, Fat, Protein, and Ash) and Minerals (Iron, Calcium, and Sodium) in Powdered Tonic Food Drink held by Food Nutrition Research Institute, Department of Science and Technology, Philippines (FNRI-DOST), Research Centre for Chemistry-LIPI conducted the estimation of uncertainty measurement in the determination of calcium (Ca) content in powdered tonic food drink using ion chromatography. The estimation of uncertainty measurement of laboratory participant of proficiency is needed for comparison with the standard deviation for proficiency assesment (?PKeywords: proficiency testing, uncertainty of measurement ) that represents fitness-for-purposes over a whole application sector in proficiency testing scheme. The evaluation of the uncertainty measurement included the several stages of procedure which consisted of the specification of measurand, identification of source of uncertainty, calculation of standard uncertainty, combined uncertainty and expanded uncertainty. The measurement result shows that the Ca content in powdered tonic food drink sample was 541.4 mg/100g, with the expanded uncertainty measurement 41.1 mg/100g (coverage factor, k = 2, at confidence level 95%). The repeatability of method measurement gave the major contribution to the uncertainty of the final results. Furthermore, the measurement result was within the consensus value and its expanded uncertainty that indicates the satisfactory result of Research Centre for Chemistry-LIPI in this proficiency testing scheme.