DEVELOPMENT OF A FASTER TECHNIQUE FOR THE SPECIATION OF POTENTIALLY TOXIC METALS IN SOIL

Abstract

The impact of potentially toxic metals (PTM) 011 humans and other organisms depend:
on their concentration, toxicity and bioavailability, which ill turn, depend in part 01
reactivity and solubility. The total concentrations of PTM do not determine tlu

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mobility, bioavailability and uptake by plants but the fraction of these metals in soil

'or sediments, hence the development of sequential extraction method which /10
been widely usedfor speciation or fractionation studies. The limitations and problem
of long extraction time associated with BCR (Community Bureau of Reference) nietlio
of extraction has led to the development of a faster and rapid Ultrasonic Assiste
method of extraction. The species of the metals ill soils was determined using bOI
the conventional BCR and ultrasonic assisted methods of extraction, {II;
quantification H'as done with Flame Atomic Absorption Spectrophotometer (FAA~
Though it l1/aS observed that the results obtained in the ultrasonic assisted ntetlu
of extraction 1vere slightly higher than those obtained in the BCR method
extraction, statistically (p<0.95) there was no significant difference in the two tnetho
for all the studied metals. Prior to comparison, the analytical performance of t
laboratory 1vas tested with a secondary reference material-Gl.A URlIl, using be
procedures and good recoveries H'ere observed ill most cases (80.6-104%). T
~'esearch showed that that the ultrasonic method with a much shorter extract;"
time happens to be a valid alternative to the conventional BCR method.