| In ICP-AES, spatial emission profiles for both radial- and axial-viewing modes were used and found to be effective to detect both matrix interference and system drift in both aqueous- and organic-solvent-based analysis. A drawback of this method was the less-than-optimal location of the crossover point in axial-viewing ICP-AES, which was earlier used to correct interference in the radial-viewing mode. As a result, an alternative method was explored, involving use of the intensity ratio of two analytical lines during a gradient dilution. Although this latter method was effective, it is less sensitive to sample-introduction-related matrix interference than the spatial-profile method. A third method was therefore developed, which combines the advantages of the other two methods and was found to be effective. The sensitive spatial profile was used to detect the existence of matrix interference, while gradient dilution was the means to correct the interference.;The gradient-dilution method was also explored in ICP-MS. This method successfully overcame the drawback of element-specific dispersion in the absence of a matrix, found with a previous method that used Flow Injection Analysis (FIA). Element-specific dispersion was found to be small or negligible in the gradient-dilution method, so matrix interference in ICP-MS could be detected and corrected. A second method to overcome this drawback was explored and termed 'aerosol dispersion'. In this method, an aliquot of sample solution was injected directly into the nebulizer to create a concentration gradient with washout time of the spray chamber. The method also successfully detected and corrected matrix interferences. |
