Performance comparison in the analysis of geological samples by ICP-OES using two novel nebulizers: MassNeb® and Micromist®
1. Introduction
In the last decade, nebulizer selection has become challenging due to the relatively wide variety available. By far, concentric nebulizers are the most common type found on instruments today, as they generally provide the best performance. Even within the narrow category of concentric nebulizers, there is quite a range of different designs. In this study, we compare the performance of MassNeb® inert, robustness and durability nebulizer manufactured by Ingeniatrics Tecnologías S.L. and one of the most stablished nebulizers in the market, Micromist® (Glass Expansion) for analytical methodologies based on ICP-OES and ICP-MS detection.

2. Experimental
Reagents and solutions
Instrumentation

Table I. Operational conditions using ICP-OES Varian 710-ES, Agilent Technologies.
Sample Preparation
3. Results and discussion
Sensitivity and signal stability
The optimal aerosol generated by the MassNeb® nebulizer is also more efficiently desolvated and excited in plasma, helping to improve precision values, typically less than 1% RSD between replicates of the same run analysis, even at low sample flow rates, which also explains why it is much more sensitive than conventional nebulizers. as well as a parallel-path nebulizer from other vendors.
To determine the optimal pump speed for sample introduction, a sensitivity study was conducted using a 5 µg kg-1 Mn solution monitored at a wavelength of 293.305 nm. A nebulization flow curve was generated for the Micromist® and MassNeb® nebulizers, with the best results obtained at 250 kPa and 10 rpm for Micromist® and 175 kPa and 7 rpm for MassNeb® (see Figure 1).

Figure 1. Nebulization flow curve for sensitivity evaluation using different nebulization gas pressure and pump speed for sample introduction represented as Intensity of 5 ppm Mn (cps) / Background signal (cps).
To do so, a monitoring standard solution containing 25 µg g-1 of each element was prepared and analyzed once every 5 mineralized CRM samples. Recoveries were monitored to ensure they fell within the acceptable range of 90-108%.
Precision and reproducibility evaluation
Table II below, summarizes the experimental registered values for each monitored wavelength with both nebulizers evaluated, as well as the RSD obtained for 3 replicates of each of the CRMs used in the experimental development of this application note. Generally, MassNeb® shown better precision and reproducibility results in comparison with the results obtained with Micromist® nebulizer.

Table II. Experimental and certified values for each monitored wavelength, as well as the RSD obtained for 3 replicates of the different CRM using Micromist® and MassNeb® nebulizers used in this study.
4. Conclusions
The results obtained in this study using MassNeb® nebulizer provides better sensitivity at lower speed pump for sample introduction to the ICP-OES instruments in comparison with the results obtained by Micromist® nebulizer.
This fact makes MassNeb® nebulizer more appropriate for the analysis of samples with high contents of highly corrosive acids, especially hydrofluoric acid, favoring the product lifespan and minimizing the deterioration of instrumental accessories and consumables of ICP instruments, as well as reduce operational incidents caused by the corrosive effect of acids used in the mineralization of samples.
Moreover, the MassNeb® nebulizer’s lower sample consumption requirement makes it particularly appealing for clinical analysis, where the amount of sample needed for ICP analysis is a crucial factor due to the use of human tissues or biological fluids.
This feature allows for more efficient and costeffective analysis, making it an attractive option for clinical researchers and practitioners.
Finally, the increased precision in the results obtained with the MassNeb® nebulizer is due to its higher sensitivity and reproducibility compared to the Micromist® nebulizer. This is a consequence of the MassNeb® nebulizer’s ability to generate a very fine droplet aerosol with a narrow size distribution, resulting in greater precision in the analysis.