In tandem-mass spectroscopy, what is the function of the first mass filter?

In tandem-mass spectroscopy, the function of the first mass filter is to selectively isolate specific ions based on their mass-to-charge ratio before they undergo further fragmentation in the second stage of the analysis. This first filter ensures that only ions of interest are allowed to proceed to the next step in the mass spectrometry process.

The isolation of specific ions is crucial for enhancing sensitivity and specificity in the analysis, as it prevents the interference from other ions that may be present in the sample. By effectively separating the ions of interest, the first mass filter helps in generating cleaner spectra, leading to more accurate quantification and identification during subsequent analysis steps.

In this context, the other options do not relate to the specific function of the first mass filter. The ion source pertains to where the sample is introduced and ionized, the chromatography column is used in separating components based on their chemical properties prior to mass analysis, and the vacuum system is essential for maintaining the conditions needed for mass analysis but does not perform the role of isolating specific ions.