Studies of matrix effects for the analysis of zinc in sodium chloride using direct sample insertion-inductively coupled plasma atomic emission spectrometry

The matrix effects on analyte vaporization and ICP excitation conditions in direct sample insertion-inductively coupled plasma atomic emission spectrometry were studied. Zn was used as a test element and NaCl as the matrix. A slow insertion speed of the sample probe was used to allow partial separation in time of the vaporization of the volatile Zn species and the NaCl matrix. Temporal studies of the Zn emission intensity indicate that ZnCl2 starts to vaporize during sample probe insertion in the presence of the NaCl matrix. The Zn intensity is reduced because the plume of Zn vapor is not concentrated in the central channel of the ICP. Temporal profiles of the intensity ratio of ZnII/ZnI also shows that introduction of a large quantity of NaCl into the ICP has little effect on the ICP excitation conditions. The ICP is, however, significantly cooled due to heat loss to the sample probe.