Why can't carbon and nitrogen be detected in ICP-MS and ICP-OES techniques?

Why can't carbon and nitrogen be detected in ICP-MS and ICP-OES techniques?


My book says this technique is efficient for detecting multiple elements, with exception of halogens and carbon. I found somewhere that ICP is an open system, therefore it doesn't allow carbon detection. But why is that exactly?




As you say, air is allowed to enter the plasma. Air consists primarily of $\ce{N2}$ and $\ce{O2}$, and would clearly interfere with any oxygen or nitrogen in the sample. The problem is not that ICP-MS or -OES cannot detect them, the problem is air. 


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As an aside, the lack of carbon and nitrogen detection by ICP-OES does not propose practical problems because there are other methods to detect them. [Combustion analysis](https://en.m.wikipedia.org/wiki/Combustion_analysis) is one such alternative.


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Like the previous answers said, nitrogen and carbon content in the air is a contaminating factor. However according to this resource I found from 2005, it is theoretically possible to analyze nitrogen via ICP-OES by making it into a closed system.
<https://www.spectroscopyonline.com/view/determination-nitrogen-and-other-essential-elements-fertilizers-icp-oes>
Using combustion analysis is fine, but it's time/labor/cost intensive, where ICP-OES is relatively cheap and easy to operate. Another trade-off is that combustion analysis is fairly reliable, while ICP-OES may have to be calibrated 2-3 times over 10 hours.


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