Hollow cathode lamps alignment

Furthermore, the radiant density of the D2 lamp in a large part of the spectrum is fairly low. Hence, the procedure limits the number of analytical lines which can be used and the number of elements that can be determined. As the spectral radiance of the D2 lamp is generally low as compared with that of a hollow cathode lamp, the latter must be operated at a low radiant output (low current), which means that detector noise limitations and poor detection limits are soon encoun-terd. Finally, as work is carried out with two primary radiation sources, which are difficult to align as they have to pass through the same zone of the atom reservoir, this may lead to further systematic errors. 

To 50 ml of the above extract add 5 ml cone. HCl and 5 ml 10% KI and wait for half an hour. This solution is feed to the AAS coupled with hydride generator together with sodium borohydride, concentrated HCl and the purger gas. (Ar or Ng) which transports the generated arsine (AsHg) to the quartz cell aligned with the arsenic hollow cathode lamp (Model GBC 932B). 

Set up the atomic absorption spectrophotometer for the air/acetylene flame analysis of cadmium according to the SOP (5.8.) or the manufacturer s operational instructions. For the source lamp, use the cadmium hollow cathode or electrodeless discharge lamp operated at the manufacturer s recommended rating for continuous operation. Allow the lamp to warm up 10 to 20 min or until the energy output stabilizes. Optimize conditions such as lamp position, burner head alignment, fuel and oxidant flow rates, etc. See the SOP or specific instrument manuals for details. Instrumental parameters for the Perkin-Elmer Model 603 used in the validation of this method are given in Attachment 1. 

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