Hi, I've been having an issue with Ca variability for a while and have run out of ideas to try to fix it. I've attached a few examples of the calibration curves. All other components are fine.

https://image2url.com/r2/default/images ... 58dd09.png

https://image2url.com/r2/default/images ... 5aced9.png

https://image2url.com/r2/default/images ... 5aced9.png

I've tried replacing all the consumables/tubing/connections and recently replaced the old Integrion systems with Inuvions, making sure that everything was completely new to avoid contamination. I've changed the method to look at the equilibration time and washes. I've also tried water from another lab to investigate the water sources and then bottled water. None of these helped with variability and I'm now completely stuck.

Has anyone seen anything like this before or have any other ideas?

Thanks in advance!