Corroded skimmer base on 7900

Question

Hello, 
 I recently removed the cones on our 7900 ICP-MS for maintenance, and saw that the skimmer base seems to be seriously corroded (see picture). There is no apparent effect on the performance of the instrument, but since it has been shut down for a long time, it is hard to make a direct comparison. And visually it looks like it could be a problem. 
 We have also been puzzled by the cause of the corrosion. Since it has previously been connected to a LC, our theory is that there has been a solvent flow on while the plasma was turned off, which led to accumulation of solvent in the interface region. This is also supported by traces of drips from the sampler cone (not in the picture). However, I have not heard of any other experiences with similar problems. 
 Do you have any suggestions 
 1) As to what can have caused the corrosion? 
 2) Whether it will pose a problem for instrument performance? 
 
 Best regards, 
 Thomas Karlsson

cschulz · Answer

Hi Thomas, 
 1) It is only a guess, but if you connect a LC to the ICP-MS, the Pump Flow of the LC is often set to 1ml/min. If so, you have to keep in mind, that the peristalitc pump needs to turn faster (0.30rps) to ensure the draining of the spray chamber. Maybe this was the root cause. 
 2) The Skimmer Base itself has no performance impact, as long it is able to provide a good contact to the interface. otherwise you will get vaccum problems. If there is any "loose" material, which can fall of the Base during an analysis, this will cause problems. So clean the base with a tooth brush and sonicate it in DI Water and it should be ok. 
 
 Best Regards 
 Chris