Roll-over of analytical curves in atomic absorption spectrometry arising from background correction with pulsed hollow-cathode lamps

1984 ◽  
Vol 39 (8) ◽  
pp. 1011-1019 ◽  
Author(s):  
L. de Galan ◽  
M.T.C. de Loos-Vollebregt
1983 ◽  
Vol 37 (5) ◽  
pp. 419-424 ◽  
Author(s):  
S. B. Smith ◽  
G. M. Hieftje

A new method is described and tested for background correction in atomic absorption spectrometry. Applicable to flame or furnace atomizers, the method is capable of correcting backgrounds caused by molecular absorption, particulate scattering, and atomic-line overlap, even up to an absorbance value of 3. Like the Zeeman approach, the new method applies its correction very near the atomic line of interest, can employ single-beam optics, and requires no auxiliary source. However, no ancillary magnet or other costly peripherals are required and working curves are single-valued. The new technique is based on the broadening which occurs in a hollow-cathode spectral line when the lamp is operated at high currents. Under such conditions, the absorbance measured for a narrow (atomic) line is low, whereas the apparent absorbance caused by a broad-band background contributor remains as high as when the lamp is operated at conventional current levels. Background correction can therefore be effected by taking the difference in absorbances measured with the lamp operated at high and low currents. The new technique is evaluated in its ability to correct several different kinds of background interference and is critically compared with competitive methods.


1995 ◽  
Vol 49 (4) ◽  
pp. 413-424 ◽  
Author(s):  
Albert Kh. Gilmutdinov ◽  
Bernard Radziuk ◽  
Michael Sperling ◽  
Bernhard Welz ◽  
Konstantin Yu. Nagulin

The spatial distribution of radiant intensity from hollow cathode lamps used as radiation sources in atomic absorption spectrometry is investigated with a digital photodiode array imaging system. Intensity distribution over the cross section of each lamp is measured for both atomic and ionic lines of the analyte and the filler gas. The shape of the distribution is strongly dependent on the hollow cathode diameter. In small cathodes the distribution has the shape of a paraboloid with maximum intensity at the hollow cathode axis for all of the recorded lines. The intensity distributions of lines emitted from large cathodes are nonparaboloid and in some cases have a minimum at the cathode axis and a maximum concentric to the cathode walls. It is shown that the intensity distribution for a given lamp has practically the same shape for all currents applied. Data on the evolution of the intensity distribution during warm-up of the lamps and under various operating conditions are presented.


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