A SIMPLIFIED METHOD FOR THE DETERMINATION OF CHROMIC OXIDE (CR2O3) WHEN USED AS AN INDEX SUBSTANCE
A SIMPLIFIED METHOD FOR THE DETERMINATION OF CHROMIC OXIDE (CR2O3) WHEN USED AS AN INDEX SUBSTANCE
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DOI：
10.1126/science.116.3023.634
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发表时间：
1952-01-01
期刊：
影响因子：
56.9
通讯作者：
KLOSTERMAN, EW
中科院分区：
文献类型：
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作者：
BOLIN, DW;KING, RP;KLOSTERMAN, EW
用钼作催化剂的酸消化已用于测定磷（3，4）。该方法已成功应用于氧化铬的测定。氧化剂的配制：将10 g碳酸钠溶于150 ml蒸馏水中。缓慢加入150 ml浓硫酸。酷了加入200 ml高氯酸（70-72%），充分混匀。分析方法：将100-500 mg含1-5% Cr2 O3的样品通过40目筛研磨，转移至干燥的100 ml凯氏定氮瓶中，校准至110或100 ml。加入5 ml氧化剂，使其将烧瓶侧面的任何粘附颗粒冲洗干净。将烧瓶放在微型燃烧器上加热，微型燃烧器的石棉板上的孔已经扩大，以便让更多的热量与烧瓶接触。氧化将在1或2分钟内开始。允许样品消化，直到获得澄清的消化混合物。在一些样品的氧化过程中，黑色颗粒粘附在烧瓶的颈部和侧面。在这些情况下，转动烧瓶1800，使样品消化2或3分钟。关闭燃烧器，向消解混合物中加入2 ml高氯酸（70-72%），然后重新加热。稍微冷却，加入50 ml蒸馏水。冷却至室温，并在经校准的凯氏定容烧瓶中定容至刻度，静置几分钟，使二氧化硅沉淀。将溶液从凯氏烧瓶中轻轻转移到比色管中，并对设定为100的蒸馏水进行读数（440 g过滤器）。通过氧化已知量的氧化铬（Cr2 O3）（用作参比物质）制备标准曲线。用蒸馏水将内容物稀释至一定体积。取该溶液的不同等分试样，用蒸馏水稀释，当使用Evelyn光电比色计时，得到10-120 pg/ml范围内的不同浓度的氧化铬。
acid digestion with molybdenum as a catalyst has been used for the determination of phosphorus (3, 4). This method has been successfully applied to the determination of chromic oxide. Preparation of oxidizing reagent: Dissolve 10 g sodium molybdate in 150 ml distilled water. Add slowly 150 ml concentrated sulfuric acid. Cool. Add 200 ml perchloric acid (70-72%) and mix thoroughly.Analytical procedure: Transfer 100-500 mg sam-ple containing 1-5% Cr2O3 which has been ground through a 40-mesh sieve to a dry 100-ml Kjeldahl flask, calibrated to 110 or 100 ml. Add 5 ml of the oxi-dizing reagent in such a manner that it will wash any adhering particles down the side of the flask. Heat flask over microburner which has had the holes in the asbestos board enlarged so as to allow more heat to come in contact with the flask. Oxidation will begin in 1 or 2 min. Allow the sample to digest until a clear digestion mixture is obtained. In the oxidation of some samples, black particles adhere to the neck and sides of the flask. In these cases turn flask 1800, allowing the samples to digest 2 or 3 min longer. Turn off the burner and add 2 ml perchloric acid (70-72%) to the digestion mixture and then reheat. Cool slightly and add 50 ml distilled water. Cool to room temperature and make up to volume in the calibrated Kjeldahl flask, and let flask stand a few minutesto allow silica to settle. Transfersolution gently from the Kjeldahl flask to a colorimetric tube, and read (440 g filter) against distilled water set at 100. Prepare a standard curve byoxidizing a known amount of chromic oxide (Cr2O3) which isto be used as a reference substance. Dilute contents to a definite volume with distilled water. Take different aliquots of this solution and dilute with distilled water to give different concentrations of chromic oxide within 10-120 pg/ml when the Evelyn Photoelectric Colorimeter is used.