We have 3 GCMS systems in our hospital lab, all running on Helium. With recent shortages, I'm curious what everyone is doing to deal with it. We have spoken about using Hydrogen but there is a lot of hesitation with bringing in a hydrogen tank into the lab.
I've already put a support ticket it, just curious if anyone else has encountered this on other QToF systems.
Out of 150+ targeted compounds, codeine constantly fails due to mass error issues. I had hoped that if other analytes were failing due to +-10 or 20ppm mass error then I would be able to reason with it. It's at a decent concentration and response appears good. RT is on point, but 1/5 times fails due to mass error issues. We changed protocols and now store the lock mass solution in the fridge and refill the fluidics once a week with fresh lock mass. upon re-injection, codeine will often appear normal with low mass error. but this is unacceptable in a clinical setting since I'd have to then re-inject everything just in case it has something missing. during validations I didn't have any issues with intra/inter assay precision
Looked at lab temperature fluctuations ( <0.5C difference), contamination (but it would affect all analytes, wouldn't it?), other possible interferences, remade all the solvents and fluidics solutions, we have a very good maintenance protocol and keep the lab quite clean. Extraction is basically a dilute-n-shoot but we use a cellulose filter to remove debris in urine.
open to trying out suggestions to identify root cause and just understand whats going on in general.