Determination of lead and chromium in wastewater using graphite furnace atomic absorption spectrometry with and without matrix modifier / Salwahalhana Ahmad Tajuddin

In this study, the amount of lead and chromium was determined in wastewater samples from Nippon Paint Factory, section 22 Shah Alam. The wastewater was treated by wet digestion method. The lead and chromium metals were then determined by graphite furnace atomic absorption spectrometry, Perkin- Elmer Model 2380 atomic absorption spectrophotometer, equipped with an HGA-300 graphite furnace, deuterium background corrector, nitrogen as the inert gas, lead and chromium electrodeless discharge lamp and coated graphite tube were employed to all adsorption measurements with and without matrix modifier. The matrix modifiers used were nitrate salts of magnesium and calcium. Before the wastewater was tested, an optimization study was done on the most suitable ashing temperatures to be used. Calibration curve of standard lead and chromium were plotted from 0.4 ppm till 2.0 ppm at ashing temperatures 750 °C and 1550 °C without matrix modifier while 850 °C and 1650 °C for metals with matrix modifier. Magnesium is the best matrix modifier in comparison to calcium because the increase in percentage of absorbance and also concentration of lead and chromium. From the analysis the concentration of lead and chromium without using matrix modifiers are 0.028 ppm respectively while using matrix modifier magnesium and calcium, the concentration increased to 0.048 ppm and 0.043 ppm for lead and 0.047 ppm and 0.043 ppm for chromium. However it still under the Environment Quality Act and it shows that the treatment system in Nippon Paint Factory is efficient in removing heavy metals from their effluent water.