A simultaneous multielement non-dispersive atomic-fluorescence spectrometer using modulated sources and frequency discrimination of fluorescence signals
Istituto di Chimica Analitica Strumentale del C.N.R.-Istituto di Chimica Analitica dell'Università Di Pisa, Via Risorgimento 35, 56100 Pisa, Italy
Istituto di Chimica-Fisica dell'Università di Pisa, Via Risorgimento 35, 56100 Pisa, Italy
Abstract:
Commercial radiofrequency-excited electrodeless discharge lamps can be run from a square-wave modulated power supply so as to give a low level of continuous emission when modulated in the frequency range 3–10 kHz. Use of a different modulation frequency and lock-in amplifier for each lamp allows multielement non-dispersive atomic-fluorescence spectrometry to be performed. Very low detection limits have been obtained for arsenic, selenium, tin and mercury. The use of low-cost electronic components in the system largely offsets the high cost of the individual excitation power supplies and tuned a.c. detectors.