What could cause a loss in sensitivity of absence of peaks?

What could cause a loss in sensitivity of absence of peaks?

Please be aware that performance-related issues that cannot be resolved by instrument cleaning are not within biocrates’ responsibility and must be handled by the user or the LC-MS engineer. Based on our experience, however, we are happy to share some suggestions:

Sample preparation:
  1. Make sure the testmix/test sample has been reconstituted or diluted correctly.
  2. Make sure there was no air in the pipette tip when transferring sample to another vial.
  3. Make sure the testmix/test sample used was not expired.
Instrumental setup: double-check all method parameters and make sure the analytical column and mobile phases were prepared and installed correctly.

Connections: check for leaks and retighten all connections.

Injection needle: the injection needle might not be correctly adjusted or draws air. Adjust positioning or replace the needle.

Injector: check for leaks or contaminations in the injector valve and rotor seal. Clean or replace the valve.

Divert valve: set to waste instead of MS. Check setting at valve and in method.

ESI electrode: leak, contamination, or defective. Reassemble ESI probe, clean with different solvents at high flow rate, or replace ESI needle.

MS: perform instrument front-end cleaning (Orifice, QJet, quadrupole, ion transfer tube etc.). Tune and calibrate the instrument.


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