Interference effects in a capillary arc excitation source for emission spectrometry

The effects of major constituents (K, Zn, and phosphate) on the emission intensities of eighteen selected analytes in a d.c. capillary arc plasma provided with a nebulizerdesolvation apparatus, are reported. Potassium and zinc enhance the emission from most of the analytes, especially that from the elements of medium ionization potential. Cesium added in excess as a buffer reduces the cation interferences to negligible proportions. The presence of phosphate results in a marked decrease in the excitation temperature of the plasma. Depression effects of phosphate, observed for all the analytes tested but Mg, Se, and La, are probably due to the reduced temperature.