Generalised standard additions

Other multivariate methods have been applied to ICP spectra for quantitative measurements. As examples, they include multicomponent spectral fitting (which is incorporated in several commercial instrument software) [81] matrix projection, which avoids measurement of background species [94,95] generalised standard additions [96] and Bayesian analysis [97]. 

The flow system is designed to permit successive injections of the sample, each one accompanied by the injection of a different standard solution. Merging of the established zones permits the efficient implementation of the standard addition method involving a fixed sample dilution. The approach was initially exploited in the routine analysis of copper/ nickel alloys by ICP-OES [22], the spectral interferences being minimised by applying the generalised standard addition method [23]. This innovation however required the preparation of a large set of standard solutions. 

When several analytes are involved, interferences due to both matrix and inter-analyte effects can occur. These interferences can be overcome by taking advantage of the generalised standard addition method, an... 

Analysis of synthetic solutions using a diode array spectrophotometer. This application of SAM involved gradient exploitation. The sample was kept undiluted ("infinite volume situation") and the standard zone was added by stream confluence with two different standard zones, multi-parametric determinations involving the generalised standard addition method were achieved [354],... 

Van Veen and De Loos-Vollebregt reviewed various chemometric procedures which had been developed during the last decade for ICP-OES analysis. In these procedures, data reduction by techniques such as digital filtering, numerical derivatives, Fourier transforms, correlation methods, expert systems, fuzzy logic, neural networks, PCA, PLS, projection methods, Kalman filtering, MLR and generalised standard additions were discussed. 

Generalised (multiple) Standard Addition Method Equation (2.20) can be applied to a data set obtained by spiking the unknown samples with known amounts of the components to be determined. In this case, the cs/ values will correspond to the added concentrations of each component in each standard. As above, the regressions performed for each measuring channel will provide the kj11 and zm values, which will represent estimates of the sensitivity of each component and the sample signal (in the absence of additive interferences), respectively. Finally, by using Eq. (2.20) with the zm values, one can calculate the concentration of each component in the unknown sample. 

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