Continuum background in inductively coupled plasma mass spectrometry

Abstract

A laboratory constructed ICP mass spectrometer has been studied to reduce the continuum background to achieve better signal to background ratios. An optical baffle plate of 6 mm diameter is found to be the best with a cone-like lens cap of 8 mm diameter. Varying the operating conditions for the plasma and mass spectrometer affect the background intensity. Increasing the voltages applied to the ion lens elements always increases the background. A weak discharge in the lens elements is considered as the cause of the increase. The variation of background with the voltage applied to the ion deflector placed in front of the detector suggests that charged species partly contribute continuum background. Detection limits for several elements under compromised conditions are reported.