Progress in atomic absorption spectroscopy employing flame and graphite cuvette techniques
ABSTRACT A simplified theory of analytical signal formation for various methods of sample atomization is proposed which takes into account the nature of sample transfer through the analytical cell and instrumental distortions of the pulse shape. An analysis of the relationships obtained shows the essential advantages of the integral absorption recording method over conventional equilibrium and peak methods. These advantages were employed to simplify the standardization procedure in the determination of impurities in the cuvette (10 −5 to 10 −8 per cent) and to develop a method of analysing solid samples by the flame technique using electric heating. The proposed theory also permitted optimization of the conditions of cuvette measurement by the peak method, making it possible to achieve record low absolute detection limits (10 −14 to 10 −15 g) and to reduce random measurement error to two per cent. The ‘transparency’ of the graphite cuvette in the vacuum spectral region was used for direct determination by atomic absorption spectroscopy of sulphur, phosphorus and iodine by their resonance lines. A possibility was established of determining phosphorus and iodine by non-resonance lines P 2136 A and I 2062 A. A method is described for determining relative oscillator strengths f in the spectra of elements from the absorption sensitivities of various lines measured by the flame technique. A comparison of the f values calculated from published sensitivity data with the most reliable values confirms the validity of the method.