Gallacetophenone Isonicotinolyhydrazone-A New Sensitive Reagent for Rapid Spectrophotometric Determination of Chromium (VI)

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Gallacetophenone isonicotinoyl hydrazone (GAPINH) forms a brownish yellow coloured soluble complex with chromium (VI) instantaneously at PH 2.70. The complex exhibits an absorption maximum at 420nm with a molar absorptivity of 1.57×104 litre mole-1 cm-1 and photometric sensitivity 0f 0.0033?g cm-2 ml-1. Beer,s law is valid over the concentration range 0.10 – 2.75 ppm of Chromium (VI) with an optimum concentration range of 0.50 – 2.60 ppm. A 5-fold molar excess of the reagent is necessary for the full development of the colour intensity. The stoichiometry between chromium and GAPINH is established as 1:1. The stability constant of the complex calculated from Job,s method was 1.56 × 105. The method is simple, sensitive and rapid.

GAPIMH; spectrophotometry; chromium (VI)