Optimization of parameters for study of heavy metals in biological samples
Kamau, Geoffrey N.
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In this work parameters such as AAS/CVAAS delay time, pH, digestion matrix, mercury reducing agents, sensitivity complexing time for XRF analysis and digestion temperature have been considered. The results demonstrates increase in instrument response with delay time, giving an optimum time of 48.3 seconds. Moreover, pH range of 1.5 to 2.0 was found to be optimal for AAS, CVAAs and XRF analysis. Reduction of mercuric ions with tin chloride yielded a signal 11.3 times that obtained with sodium borohydride. A negative correlation of mercury response with digestion temperature was observed, suggesting an optimum temperature of 50≠3 degrees centigrade for mercury analysis. A digestion temperature beyond 80oC was found to waste useful analytical time for cadmium determination. A digestion matrix of HNO3, HCIO4 and H2SO4 in ratio of 3:1:1 was effective for mercury and cadmium analysis; whereas acid mixture of HNO3 and HCIO4(3:1) was found most appropriate for lead determination. The analytical procedures used in the present work were reliable and reproducible, as demonstrated by results of standard reference materials