As LC Triple Quadrupole Mass Spectrometers (LC/TQ) have continued to become more sensitive to analytes, the capability to detect contaminants has also increased. The advent of Agilent Jet Stream ion source and iFunnel technologies starting with the Agilent 6490A, have contributed with the increasing sensitivity of the systems. It becomes more important to make sure that the entire flow path is clean. This article gives some specific examples of common contaminants found in LC/TQ systems and some tips on how to prevent and remove these types of contamination.
Note: It is uncommon to see all three contaminant classes described in the following sections, in the same instrument. However it is not uncommon to see one or two of these contaminant classes in combination in the same LC/TQ.
Steps to follow.
To compare your LC/TQ instrument to the following examples, please implement MS2 scan data collection (also known as- no injection to help identify background or contaminant issues. To ensure an accurate comparison, the chromatography (including gradient) and MS methods (including delta EMV) remain the same as the acquisition method you are currently using for your application.
Figure 3: Total Ion Chromatogram (TIC) showing abundance in the 1 - 1.7x 108 range.
Figure 4: MS2 Scan showing the major PEG contamination ions
Figure 5: MS2 Scan showing a reduction in contamination ions after EDTA and Aqueous flushing. Triton ions can still be seen.
|Dibutyl sebacate, plasticizer
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