Comparison of Three Methods of Digestion for Trace Metal Analysis in Surface Dust Collected from an EwasteRecycling Site
2012
The recycling of e-waste materials potentially contaminates the environment with heavy metals.
Analysing the exact contents of heavy metal in e-waste products is germane for the routine monitoring, risk
assessment and regulation of the environment. Therefore, the efficiency of three methods of digestion was evaluated
for Cd, Fe, Pb, Cr and Zn by AAS in surface dust from an e-waste recycling site and to recommend the most
efficient digestion method. The digestion methods were aqua regia, dry ashing followed by aqua regia and nitric acid
digestion followed by extraction with HCl. Analysis of variance, Student’s t-test and F-test were performed
separately for the indoor, outdoor and control dust samples analytical result. Analytical results indicated that the
nitric acid digestion followed by extraction with HCl was the most efficient in recovering Pb and Fe based on
recovery efficiency. Aqua regia was found to be an alternative method for recovering Pb and Fe based on cost and
time effectiveness. Aqua regia was the most efficient in recovering Zn while aqua regia and nitric acid digestion
followed by extraction with HCl were satisfactory for the recovery of Cd. Dry ashing followed by aqua regia was
found unsuitable for the analysis of these metals in the samples because it recovers relatively little heavy metals and
more analysis time.
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