Background spectral stripping

The figures of merit of primary interest to analytical chemist that are discussed are noise characteristics and powers of detection, linearity and dynamic range, spectral stripping and interpolative correction for variable underlying background, compromise between resolution and spectral coverage and application to nonideal "real" samples. 

Figure 8. Analytical calibration for Ti 190.8 nm after spectral stripping with 1% HNO blank and interpolative background correction. Concomitant concentrations are the...

Useful interface which Is applicable to a wide range of molecules. The volatile solvent molecules are stripped from the sample and lost in a process similar to that used in the early jet separators used in GC-MS. The heavier sample molecules enter the MS and can be ionised by the standard methods of El, PICI or NICI. Gives spectra with El fragmentation which can be referred for identification to El spectral libraries built up over many years. No solvent background thus sensitive to the 1(h g level. Solvent flow rate up to 1 ml/min, mass range up to 1000 amu... 

ETAAS. In ETAAS atomization takes place in an electrothermal atomizer which is heated to the appropriate temperature programme. The detection limits of the method are about two or three orders of magnitude better than FAAS. It is applicable to about 40 elements but generally for about 20 elements detection limits at the ng and pg level can be reached. Commensurable or better sensitivities have only INAA, ICP-MS and stripping voltammetry. Therefore ETAAS is widely used for environmental analysis. However the method suffers from serious interferences leading to systematic errors due to thermochemical processes in the atomizer. Background absorption is also a potential source for systematic errors. Spectral interferences are additive and cannot be corrected by the popular standard addition method. ETAAS is also not free of memory effects for refractory elements. 

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