Cross-flow nebulisers and testing procedures for inductively coupled plasma nebulisers
The performance of cross-flow pneumatic nebulisers for the inductively coupled plasma was studied. The parameters studied included the precision of the analytical signal and its stability. The test protocol was chosen to provide a performance index (PI) for the nebulisers in order to rate them. The PI is based on the average short-term relative standard deviations (RSDs) measured over extended periods of time. The measurements were used to test reliability across different lots of nebulisers and to investigate the consistency of performance. Also, the effects on performance of replacing the removable cross-flow tips was studied. The test protocol included the use of Triton X-100 surfactant in the standards to eliminate potential variability of wetting in the spray chamber. The use of surfactant also helps to ensure the smooth transfer of the sample liquid through the pump and capillary tubing leading to the nebuliser. The PI for the cross-flow nebulisers was typically between 0.5 and 1.0% and always less than 1.5%, expressed as RSD.