Application of the Faraday effect to the trace determination of cadmium by atomic spectroscopy with an electrothermal atomiser

Abstract

As a technique for the trace determination of elements, the Faraday effect has been applied to atomic spectroscopy with the use of electrothermal atomisers. The atomiser was located between two crossed plane-polarisers (called the polariser and the analyser). An electromagnet magnetised the atomised sample and, as a result of the Faraday effect, the source radiation could, in the presence of the atomic vapour, pass through the optical system. A simple theoretical treatment was developed to explain the dependence of the transmitted intensity on the magnetic field strength and the source intensity and the ability to eliminate the effects of background scattering.

Measurements on cadmium were carried out at a wavelength of 228.8 nm, dispensing into the atomiser 5-µl samples, which, after drying, were atomised at 1000–1800 °C. The calibration graphs demonstrated a square-law dependence. At high concentrations the calibration graphs were corrected for atomic absorption. The technique gave a detection limit of 5 × 10^–13 g for cadmium.