ICP-OES 5800 Chromium falling out after couple hours

Lately, I've been having issues with my Chromium. It calibrates fine at first, but over the course of the day the recovery in my CCVs steadily climbs until it becomes unusable. This used to happen only occasionally, but now it's happening daily, regardless of tubing replacements, cleaning, standard prep, or any other factor I can think of.

In troubleshooting, I've figured out that on day when it behaves,  my midpoint of 500 ug/L comes in at ~10,000 c/s. On days when it becomes a problem, the same midpoint can be anywhere from 5000-8000 c/s. I'm thinking that it's counting low at first during calibration, then recovering after, but for the life of me I can't figure out why. No other analyte does this. Blanks remain okay, at least.

If it helps, I've set Cr at 267.716 nm, Axial viewing.

Parents Reply
  • Already have a Yttrium internal standard. Even in longer runs, it stays between 97-101% recovery. It will drop lower with particularly dirty samples, but it doesn't carry over, and my CCV is almost always at 99%.

    As for Argon... I'd have to redo all my IEC standards to add it, but for today I could at least keep an eye on my gas flow and pressure over time, as well as instrument temp. If those drift over time, it might provide some insight You are right, though. If those were the case, it should affect more than just Cr.

    Additionally, there's an ICP-MS hooked up to the same argon line as my machine is, and we both use the same standard mixes. They're not having the same issue.

No Data
Was this helpful?