Wed Dec 01, 2021 3:38 pm by mleipold
Hi Tomer,
It's weird that it's as repetitive as it is. If these were random fluctations, you'd expect random spikes. When we've had a wonky gas supply manifold, it's been jumpy, but not as repetitive as what you're seeing.
The spike appears to be a *spike*, rather than a momentary return to normal. Most often you see this with a partially clogged nebulizer bursting through, though formally any increase in flow rate (PSI argon pressure spike from a misbehaving gas manifold or partially clogged flow sensor), etc) would cause it.
Also, it seems unlikely to be a vacuum pump issue, or a cone o-ring issue: those usually manifest as fairly consistent overall low signal, as does a skimmer needing to be replaced or a broken skimmer charging connection (the copper thing the skimmer screws down against).
A few questions:
1. Even though you've changed your PSI, do you have a Supersampler to test? This would help isolate once and for all that the PSI itself (and its associated gas flow and flow meter) isn't the problem.
- I bring this up because we did have one instance in which a new PSI had to be swapped out *again* in less than a month, due to either an irreversible clog in the flow sensor or the flow sensor just became unreliable.
2. Have you tried changing the Nebulizer gas line?
3. Have you tried changing out the spray chamber (unfortunately, you need to order that part even if you have a service contract)?
- 2 and 3 would help make sure the issue is *inside* the instrument, rather than something the user can touch.
4. Do you see the same spiking with Tuning Solution, or is it just with particulates (Beads, Cells, etc)?
Mike
PS: I will say, your Bead signal on Slide 1 (consistent flow, before 17 Oct 2021) seems low. Was the instrument warmed up and tuned before this measurement was taken? In our hands, Ce140 signal is always above 1e3 if the instrument is tuned properly. In fact, we use that as a metric while running: if the Beads start dropped to 1e3 or below (long run, dirty sample, etc), we stop, Wash, and then re-Tune.....usually at least the DV has changed significantly.