A novel source for spectrochemical analysis

The paper introduces a novel excitation source, based on an AC are. The are forms across a 1 cm gap between two platinum electrodes; the applied open circuit voltage is 13 kV and the closed circuit current is 30 mA. Two distinct regions are observed: the current channel, luminous and thin, and a plane-like triangular envelope, 1 cm high, approximately, above it. Source temperature was estimated using Fe spectral lines and found to be similar to 3500K. A peristaltic pump is operated to provide sample flow rate of 0.4 mt min(-1). The sample is fed to an ultrasonic nebulizer (20 KHz) for conveying the sample into the source without recourse to a carrier gas. The efficiency of the nebulizer is similar to 30%; the rest of the solution, together with the gases formed in the are (NO, NO2), are removed through a NaOH trap by means of a simple circulating pump. Signals for 19 elements were obtained and the extensive analytical applicability of the method demonstrated by appropriate calibration curves. Sensitivity varies from element to element, and suffices for the determination of Li, K, and Ca in blood serum. The main advantages of this novel emission source are its low acquisition and operation costs and its operation in air (with no additional gas required). The system is non-polluting and can be adapted to clinical laboratories.