Correction of the sensitivity difference in atomic absorption spectrophotometry of chromium

  • OGURO Hiroshi
    Central Research Laboratory, Matsushita Electric Industrial Co., Ltd.

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Other Title
  • クロムの原子吸光分析における感度差の補正
  • クロム ノ ゲンシ キュウコウ ブンセキ ニ オケル カンドサ ノ ホセイ

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Abstract

The sensitivity difference of four different chromium compounds and a method for eliminating it were studied.<BR>A Nippon Jarrell-Ash model AA-1 atomic absorption/flame emission spectrophotometer was used fitted with a slit burner for air-acetylene flame and a HETCO total consumption burner for air-hydrogen flame under the conditions shown in Table 1. As shown in Fig. 1, the four chromium compounds gave the same sensitivity at an acetylene flow-rate of 1.7 l/min or less. At faster acetylene flow-rates, each chromium compound gave the different sensitivity. As shown in Fig. 2, the sensitivity difference as also recognized at any hydrogen pressure in an air-hydrogen flame. The relative sensitivities were as follows: (NH4)2CrO4>K2Cr2O7>CrCl3> K2CrO4 (air-acetylene flame) and K2Cr2O7> (NH4)2CrO4 > K2CrO4> CrCl3 (air-hydrogen flame). A method for eliminating such sensitivity difference was studied by the addition of ammonium chloride which yields an intensive enhancement interference on chromium. As shown in Fig. 3, with 0.02 M (air-acetylene flame) and 0.005 M (air-hydrogen flame) ammonium chloride, the absorbance became a substantially constant values. As shown in Figs. 4 and 5, at any acetylene flow-rate and hydrogen pressure, each chromium compound gave the same absorbance in the presence of ammonium chloride. These facts open up the possibility of using any chromium compound as a standard. Also the accurate estimation of the total amount of chromium in a sample solution containing various chromium compounds becomes possible by the additon of ammonium chloride to both the sample and standard solutions. Examples of analytical results are shown in Table 2.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 24 (6), 361-365, 1975

    The Japan Society for Analytical Chemistry

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