Method validation for the determination of hexavalent chromium in seawater and other matrices by colorimetric method / Yong Pui San

The research project is about the method validation for the determination of hexavalent chromium in seawater and other matrices by colorimetric method. This method is validated by referring to the APHA 3500 B- Cr Colorimetric Method. The current colorimetric method of determination of hexavalent chromium in wastewater is carried out by using UV-VIS Spectrocopy. This method is developed to determine the trace level of hexavalent chromium up to a minimum 0.001 mg /L or 1 ppb of hexavalent chromium in seawater, river water and industrial effluent by using the Discrete Analyzer. The calibration range is within 0 to 0.25 mg Cr 6+/L or 250 ppb. In the method validation study, various concentration level of hexavalent chromium were spiked in various matrices where the recovery that were obtained within 88 % to 105 %. The instrument detection limit is 0.001 mg/L or 1 ppb. The measurement uncertainty is 0.05 ± 0.005 mg/L Cr 6+. The hexavalent chromium is determined colorimetrically by reaction with diphenylcarbazide in acid solution where the red-violet color of unknown composition will be produced. The absorbance is measured at 550 nm.