Determination of Heavy Metals in Water Samples using Sodium Sulfide Precipitation and Inorganic Coagulation Followed by Faas Detection

Studies on determination of five heavy metals, i.e. copper (Cu), cadmium (Cd), chromium (Cr), lead (Pb) and nickel
(Ni) in water samples collected from drains located outside five factories using sodium sulfide precipitation and
aluminium sulphate inorganic coagulation followed by FAAS detection were carried out. The amount of coagulant
added, effect of centrifugation time and analysis methods have been developed and optimized. Samples was
analysed by FAAS after undergone digestion with 1:1 nitric acid according to EPA Method 200.7. The recoveries of
analytes were in the range of 68 to 99.2.% The relative standard deviations of the studied five elements were found
in the range of 0.1-12.5%. The method detection limit of Cu, Cd, Cr, Pb and Ni were 0.043, 0.012, 0.011, 0.020 and
0.008 mg/L. The presented coprecipitation procedure was successfully applied to determine five free elements in the
environmental samples collected from the drains surrounding the factories. The concentration of the heavy metals in
the collected water samples were not exceeded the maximum contamination levels which stipulated under
Environmental Quality Act 1974.