Chemical and Physical Analysis
Sensitivity Improvement Mechanism of the Mistral Desolvating Sample Introduction to ICP-MS/AES and Its Application to Steel Analysis
2018 年 58 巻 6 号 p. 1061-1068
詳細
2018 年 58 巻 6 号 p. 1061-1068
Mistral Desolvation (MD), a sample introduction method for Inductively Coupled Plasma (ICP)-Atomic Emission Spectroscopy (AES) and Mass Spectrometry (MS), provides sensitivity enhancement over 5 times compared to conventional sample introduction method. Some groups have been proposed different mechanisms of sensitivity enhancement by MD, e.g. inhibition of poly-atomic ion generation derived from solvent, influence of the change of plasma condition, and improvement of sample transportation efficiency in plasma. However, uniform understanding has not been obtained.
In this paper, we have identified the dominant factor of a sensitivity enhancement by MD and examined application to chemical analysis of steel samples. It was found that the MD method provided a decrease of 100–250 K plasma temperature, which led to sensitivity loss. On the other hand, sample transportation efficiency was improved by a factor of 4.7 times owing to an increase in the sum of small droplets. This improvement was comparable to fivefold sensitivity enhancement. Thus, it was concluded that the dominant factor of sensitivity enhancement achieved by the MD method was improvement of sample transportation efficiency with decreasing droplet size.
Besides, the steel certified reference materials have analyzed by MD-ICP-AES. It was found that almost tenth amount of sample consumption and almost 3-fold sensitivity improvement could be achieved, the analyzed value corresponded exactly to certificated value. Thus, in case of a little amount of sample for chemical analysis, for example, sampling from a defected part or a corroded part, this method can be useful due to the high sensitivity and the small sample consumption.
