Chromatography Forum

For our negative mode panel on our Sciex 5500 QTRAP we are having issues with 2 analytes. The Calibaration curve and QC are having widely different concentartion between the first and second transition.

For example, the concentration of the quantifier is 101 and the Qualifier is 142. Another example; the quantifier is 78 and the qualifier is 126.

The chromatography looks good and the peak shapes are normal. Normally the concentrations would be 1:1. The problem is somewhat random; sometimes the concentrations are 1:1 but a handful are quite different.

It is only happening in 2 analytes. Any ideas as to what could cause this? I can provide more info if it helps diagnose.

Thank you greatly for you help!

Where exactly do you see differences in ion ratios? Between analyte in solvent and analyte in QC, or also between analyte in solvent one injection to the other one?

We run a calibration curve, and then follow it with QC. Certain injections have the issues within the cal curve and qc.

What is the number if transitions being acquired at the time these problem peaks elute and what are the dwell times?

How many scans are you getting from the beginning of the peak to the end of the peak?