The influence of true simultaneous internal standardization and backgroundcorrection on repeatability for laser ablation and the slurry technique coupled to ICP emission spectrometry

For the solid sampling techniques laser ablation and the slurry technique, the influence of simultaneous measurement vs. sequential measurement of the signal and background and the internal standard was investigated on an ide ntical data set. The experiments were carried out with an array spectromete r, which generates spectra rather than single points. These spectra, typica lly measured around the analyte wavelength, are measured simultaneously. Th e ICP spectrometer used has a 'profiling' mode, whereby the entrance slit i s moved fourfold and the spectra are recorded with a small spectral shift i n a sequential manner. These images are then combined to form a spectrum wh ich is composed of simultaneous and sequential measured data. Hence, by car efully selecting the data points in a measured spectrum, the difference bet ween simultaneous and sequential measurements can be estimated from an iden tical data set. In the example studied, simultaneous background correction and simultaneous internal standardization (typical for array ICP-OES) gave a mean RSD of 3.6%, sequential background correction and simultaneous inter nal standardization (typical for simultaneous ICP-OES) produced an average RSD of 6.1% and sequential background correction and sequential internal st andardization (typical for sequential ICP-OES) resulted in a mean RSD of 6. 4%. The RSDs reflect the solid sampling procedure. Some applications of las er ablation and slurry sampling are presented.