This Information Applies To the Following Products: All Agilent iFunnel and Agilent Jet Stream (AJS) 6400 Series LC/MS triple quadrupole systems, Agilent 6460A/C, 6470A, 6490A, and 6495A/B/C
Issue:
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 Solvent Blank Scan - 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.
Inorganic Clusters - Example of Acetonitrile-Cu clusters
Figure 1: MS2 Scan showing contamination in the low mass range.
Figure 2: Zoom of MS2 Scan showing a cluster of ions around m/z 145
Mass of monoisotopic ion | Ion Type | Potential source of contaminant |
144.98215 | [(CH3CN)2+63Cu]+ | Acetonitrile |
146.98034 | [(CH3CN)2+65Cu]+ | Acetonitrile |
Solution
Polyethylene Glycol (PEGs) [C2H4O]nH2O·K
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
Mass of monoisotopic ion | Ion Type | Formula for subunit AnB shown in column 2 |
151.09649 | [A3B+H]+ | [C2H4O]nH2O |
173.07843 | [A3B+Na]+ | [C2H4O]nH2O |
195.12270 | [A3B+Na]+ | [C2H4O]nH2O |
217.10465 | [A4B+H]+ | [C2H4O]nH2O |
233.07858 | [A4B+K]+ | [C2H4O]nH2O |
Solution
Possible Causes
Triton and Triton Reduced (Detergent) [C15H30O][C2H4O]n
Figure 5: MS2 Scan showing a reduction in contamination ions after EDTA and Aqueous flushing. Triton ions can still be seen.
Mass of monoisotopic ion | Ion Type | Formula for M or subunit AB shown in column 2 | Potential source of contaminant |
293.24510 | [AB1+Na]+ | [C15H30O][C2H4O]n | Triton, reduced |
315.25299 | [M+H]+ | C18H34O4 | Dibutyl sebacate, plasticizer |
Solution
Possible Causes
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