Iron Data using the Nu Plasma 1700

In order to illustrate the high resolution performance of the Nu Plasma 1700 mass spectrometer the isotope ratios of iron have been measured using Aldrich and Alfa ICP iron standard solutions. There are well known polyatomic interferences of the iron peaks namely, argon oxide, nitride and hydroxide formed in the plasma expansion process which require a resolving power of >2600 to separate them. These interferences can be greatly reduced by using a desolvating nebuliser as the sample introduction system. However, for most of this work, we have decided to enhance the contribution of these interferences to demonstrate the instrument performance, by using a “wet” plasma with shielded torch and running the samples in nitric acid (rather than HCl). In this manner we have been able to increase the level of the ArO peak, which lies adjacent to the 56Fe peak, to a level normally not encountered when using our instruments. Further, all the reported data were obtained by using the true, electronic, baseline, rather than with measurements of blank solutions, which can hide poor resolution performance.