Solid sample introduction in inductively coupled plasma emission spectrometry.

This Thesis describes the progress made in the area of solid sample introduction in Inductively Coupled Plasma Emission Spectrometry (ICP-ES). As an alternative to solution nebulisation two methods of introducing samples to the ICP are investigated. The first of these uses the direct insertion probe technique first described by Horlick and Salin (63). The assembly utilised an electrically operated graphite rod system. This could be used equally well with small volumes of solution sample (5ul) or small masses of solid sample (Ca.5mg). The variables of cup dimensions and material were investigated along with volume and masses of sample used. Results of calibration of both solution residues and solid samples are presented along with details of Limit of Detection and sample Relative Standard Deviation (RSD). The comparative data were found to be in good agreement and it was established that solutions derived calibration data could be used for the analysis of Ni-base samples. Other solid matrices, elemental and alloyed were investigated. These materials divided into two groups, (1) low volatility matrix, from which trace elements were released and only minimal emission from matrix elements was detected and there were no spectral interference effects, (2) volatile matrix in which the matrix vaporized in the same temperature range as the trace elements, giving rise to substantial matrix emission and spectral interferences. It was concluded that DI-ICP-ES is at its most useful when dealing with easily volatilized trace elements in a relatively involatile matrix. The second approach to sample introduction involved the use of an electrothermal vaporization cell. This provided precise control of temperature and offered considerably higher final temperatures than the direct insertion probe system. An Electrothermal Vaporization (ETV) device was designed and built in the laboratory and interfaced to the ICP such that vapour produced in the cell was carried into the plasma discharge by the 'injector' gas stream. ETV was used for liquid and solid samples and results for these samples are presented.