不定方程式の近似解を用いるキレート滴定によるマグネシウムの定量

概要

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An approach is proposed for the measurement of magnesium by chelatometric titration with EDTA in the presence of foreign cations (such as calcium, strontium, barium, or zinc) followed by a mathematical data treatment. Magnesium can be measured using a given equation, Y=1/(b+k)=1/(A+k-ax), where A (ml) is the amount of an EDTA solution added in the titration, a (ml/mg) is the amount of the EDTA solution equivalent to 1 mg of magnesium, x (mg) is the amount of magnesium, b (ml) is the amount of the EDTA solution equivalent to foreign cations, and k=A (ml). An approximate solution of x can be roughly estimated from the shape of the curve in the relation between Y and Y^2 values obtained by substituting the arithmetical increasing values with the common difference A/8 a in the range of 0 to A/a into x for the equation. Then a more accurate approximate solution of x is graphically estimated from the rough approximate value of x by using a similar method. By the proposed method, 0.04〜1.5 mg of magnesium in synthetic sample solutions, water samples, soy sauce, and milk, in the presence of foreign cations such as less than 4 mg of calcium, can be measured with recoveries of 99〜103% and a relative standard deviation of 0.13〜8.1%(n=4).
社団法人日本農芸化学会の論文
1996-07-01