COLORIMETRIC DETERMINATION OF SOME TRANSITION METALS IN SELECTED INI-ANT MILK FORMULAE.
COLORIMETRIC DETERMINATION OF SOME TRANSITION METALS IN SELECTED INI-ANT MILK FORMULAE.
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Date
1997-11
Authors
CHIME, CHARLES CHUKWUMA
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Abstract
Infant formulas were digested with nitric acid and sulphuric acid (5:1); furnace ashed at 500
± 10°C; and treated with 10% solution of trichloroacetic acid (TCAA). The resulting
concentrates were analyzed colorimetrieally for iron, using 1,10-phenanthroline, and 2,2'-
Bipyridyl as ligands; 2,9-dimethyl-1,10-phenanthroline for copper; Dithiozone in
carbontetrachloride for zinc; Potassium periodate for manganese; Nitroso-R-salt for Cobalt;
and Dithiozone for Lead. Atomic Absorption Speetrophotometric (AAS) analyses of the
metal ions in the three sample preparations were also done. Most coexisting metal ions
found to interfere were conveniently masked prior to the determination. Recoveries of
added ion for each of the metal ions were investigated colorimetrically using the three
preparations. On statistical comparison of the results obtained from the colorimetric
methods with the standard (AAS) method, the accuracy and acceptability of the colorimetric
methods were assessed.
Six organic reagents namely: Benzidine, 1,2,3-trihydroxylbenzene (Pyrogallol), Rodizonic
acid, Flourescien, Picric acid, and Mercaptoethanol were tested for their colored complex
formation with iron, copper, zinc and manganese. Pyrogallol found to form stable complex
that could enable the colorimetric determination of iron, was exploited in estimating iron in
the sample preparations. The results obtained were acceptable and relate well with the AAS
method.
Other essential parameters in infant formula were determined and compared statistically
with the values displayed by the manufacturers. It was found that only the results for
copper, zinc and manganese compared very well with the manufacturers values. The results
for the other parameters varied from sample to sample.
Description
A THESIS SUBMITTED TO THE POST GRADUATE SCHOOL, AHMADU BELLO
UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR
THE AWARD OF THE DEGREE OF MASTER OF SCIENCE IN ANALYTICAL
CHEMISTRY
DEPARTMENT OF CHEMISTRY
FACULTY OF SCIENCE,
AHMADU BELLO UNIVERSITY,
ZARIA - NIGERIA
NOVEMBER, 1997.
Keywords
COLORIMETRIC,, DETERMINATION,, TRANSITION METALS, INI-ANT MILK FORMULAE.