The following causes are possible.
1. The wrong standard sample was used.
2. The standard sample is old (the spectrum has changed).
3. There is a leak in the tubing of the standard sample introduction unit.
Click here for Maintenance of the Standard Sample Introduction Unit.
4. The resistance tube is clogged.
Click here for Maintenance of the Standard Sample Introduction Unit.
5. There is not a sufficient volume of standard sample in the standard sample bottle.
6. The ESI probe unit is out of position.
Adjust the ESI probe position to gain a stronger target m/z intensity.
In particular, check that negative ions are m/z 1007 and that positive ions are m/z 1224 (1004.60: LCMS-2020, 8030/40).
Click here for ESI/DUIS spray position adjustment.
7. An interference peak exists around the target m/z.
After washing the ESI probe tubing with water or methanol, check that there is no interference peak around the target m/z in the manual tuning window.
8. The target m/z intensity decreases when using substances such as TFA.
In negative tuning, the sensitivity of the raffinose peak used for mass calibration can drop substantially depending on the type of mobile phase. This is due to the fact that mobile phase derivatives are added to the raffinose.
If this happens, the mass used for mass calibration has to be changed.
Check the negative ions that are observed in Manual Tuning and enter the mass to be used for mass calibration.
CAUTION: When implementing regular auto tuning normally, do NOT change the mass used for mass calibration.
«LCMS-8030/40/45/50/60»
«LCMS-2020»