フレーム光度法による乳児用調製粉乳中のルビジウムの定量

概要

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The rubidium content of infant formulas was determined by flame photometry using the atomic absorption spectrophotometer (AAS) with air-acetylene flame. In this work, the optimum instrumental conditions for rubidium analysis were determined: the burner height of AAS, the acetylene pressure, the hydrochloric add concentration as a measuring solution and so on. The effects of coexisting ions expected from matrix components of infant formulas were tested; the results showed no interferences of Na^+, Ca^<2+>, Mg^<2+>, PO_4^<3-> (〜250μg/ml) and K^+ (〜25μg/ml). In addition, a variation of the sample amount (0.1〜1 g) for the analysis did not interfere with the determination of the rubidium content of the sample. Rubidium was determined as follows: A sample (0.3 g) in a beaker (50 ml volume) was decomposed by heating with a nitric-perchloric add mixture on a hot-plate; the solution was then diluted to 100 ml with water after the addition of 2 ml of 6 mol/l hydrochloric acid. Standard rubidium was recovered to be 100±0.9 (n=20) from an infant formula sample. This method was applied to 24 infant formula samples, resulting in the fact that there was a significant difference in the rubidium content between 10.7±2.9 μg/g (n=14) in follow-up formulas and 5.35±1.71 μg/g (n=10) in young infant formulas (p<0.05).
社団法人日本分析化学会の論文
2005-01-05