Reduction of Matrix-Induced Interferences

However, the design of the ion-focusing system or the number of lens components used is not as important as its ability to handle real-world matrices. Most lens systems can operate in a simple aqueous sample because there are relatively few matrix ions to suppress the analyte ions. The test of the ion optics comes when samples with a real matrix are encountered. When a large number of matrix ions are present in the system, they can physically knock the analyte ions out of the ion beam. This shows 

The percentage matrix suppression at each mass can then be calculated as follows  

FIGURE 22.9 If the interface is grounded correctly, signals for 1 ppb Li+, In+, and 208pb+ should all track each other and have similar optimum values as the nebulizer gas flow is changed. 

In laboratories where high sample throughput is a requirement, the overall cost of analysis is a significant driving force determining what type of instrument is purchased. However, in a high-workload laboratory there sometimes has to be 

The other aspect of sample throughput is the time it takes for the sample to be aspirated through the sample introduction system into the mass spectrometer, reach a steady-state signal, and then be washed out when the analysis is complete. The wash-in and wash-out characteristics of the instrument will most definitely impact its sample throughput capabilities. Therefore, it is important for you to know what these times are for the system you are evaluating. You should also be aware that if the 

Practical Guide to ICP-MS A Tutorial for Beginners, Second Edition 

It is also important to understand that an additional role of the ion optic system is to stop particulates and neutral species from making it through to the detector, which would increase the noise of the background signal. This will certainly impact the instrument s detection capability in the presence of complex matrices. Therefore, it is definitely worth carrying ont a DL test in a difficult matrix such as lead or uranium, which tests the ability of the ion optics to transport the maximum number of analyte ions while rejecting the maximum number of matrix ions, neutral species, and particulates. 

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