ホウ酸半融法によるアルミナ質材料中の酸化カルシウムの定量

概要

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A 0.500g sample is pulverized in an agate mortar, mixed with 1.5g of boric acid and transferred into a platinum crucible. The mixture is heated gently for (5〜10)min, and ignited for 5 min after the bubbling has ceased. The crucible is gently boiled for 20 min in a 100ml water-0.5ml hydrochloric acid (1+1) mixture placed in a 200ml beaker. Crucible walls are rubbed with a class rod, and the crucible is taken away. The solution is boiled for 5 min, filtered through No.5B filter paper together with a small amount of filter pulb, and diluted to 250ml with water. To a 100ml aliquot is added a small amount of ascorbic acid, triethanolamine, potassium cyanide, 20% potassium hydroxide (to give a pH 12.8), and finally about 10mg each of calcein and methylthymol blue (both 1:100 K_2SO_4). Calcium in the aliquot is determined volumetrically with 0.01M EDTA (from green fluorescence to dark orange). The analytical results agreed well with those by JIS method, but the present method is simpler because the calcium oxide blank in sodium carbonate used in JIS method is difficult to correct. If necessary, magnesium, sodium, and potassium can also be determined.
社団法人日本分析化学会の論文
1978-08-05