Images of the Direct Sample Insertion Process in an Inductively Coupled Plasma

Abstract

An inductively coupled plasma was imaged with a charge coupled device camera through interference filters during direct sample insertion. Images were acquired throughout the insertion and revealed how the analyte behaves in the plasma. Graphite cups, graphite tubes and wire loops were used as sample carrying probes. The diameter of the graphite cup has a dramatic effect on the plasma and calcium emission. Narrower cups disturb the plasma the least and keep the calcium within the center of the plasma. The use of a carrier gas through a graphite tube and hollow stem cup shows that a darker central channel is established. The use of a central gas in combination with Freon-12 yields a performance comparable to that of wire loops. In the case of a deep and narrow graphite cup the analyte appears to emerge into the plasma along the walls of the cup.