Transient signal drop
I recently ran some samples for a user and in a number of them saw an artifact that I haven't noticed previously. Basically, there were transient sharp drops in signal and then then a rapid ramping up to the "normal" signal. This was best seen using a bead channel and I've attached an example image.
My first thought was, obviously, a transient clog and there were indeed a number of clogs on the day, and the event rate did vary at times. However this doesn't match well with previous experience where - as far as I have observed - transient clogs come out looking like a brief break in the signal rather than a drop in intensity. I went back and looked at a number of recent experiments and noted the "break" phenomenon but not the "drop" one I'm describing here.
Another theoretical argument I had against this being a clog was that if a particle can make it through the nebulizer and spray chamber into the plasma then I'd assume that it should form a coherent cloud of ions that would be analyzed efficiently (and therefore not show decreased signal). So - my best guess so far is that the effect originates somewhere downstream of the plasma. Any comments on this appreciated...