CORRECTION SYSTEM FOR SPECTROSCOPIC DETERMINATION OF TRACE AMOUNTS OF CADMIUM USING THE ATOMIC FARADAY-EFFECT WITH ELECTRO-THERMAL ATOMIZATION

The effect of background absorption of radiation on the signal obtained in Faraday-effect atomic spectroscopy has been overcome by comparing the energies transmitted when the optical polarisers are in crossed and parallel configurations. Two systems were developed: one was a static system in which a Glan prism was used to divide the optical beam into two beams of orthogonally polarised radiation that were detected by two photomultipliers; the other system used a rotating prism to rotate the plane of polarisation of the optical beam and a single photomultiplier with time-sharing electronics to separate the required signals. Cadmium in a starch matrix was determined using the spectral line at 228.8 nm and losses of incident radiation of up to 99% were corrected successfully.