[uros]

Hello everyone!
I am using graphite furnace (Perkin Elmer, AAnalyst700) to determine As, Pb, Cd... concentration in water samples for several years. For some time I am getting lower signals (sometimes very low) for standard solutions (they are OK), i.e. large characteristic mass. Also, during the course of analysis signal weakens (series of 10-20 samples).

Another thing is that graphite cuvettes degrade quickly (after 20 semples they are done).
I've noticed that there are white marks around holes in left contact cylinder from which inert gas flows around cuvette. Just beneath those 3 holes the cuvette is getting etched (like a ring around cuvette near the place where cuvette meets left contact cylinder) and eventually pierced.

Please, answer me what could cause that? Technical support couldn't help me, and I changed cylinders recently but the problem persisted.

[FireflySci]

Hi Uros.  I'm sorry I noticed you posted this awhile ago and I would like to help you solve this issue.  Can you post a photo of your setup so I can see what is happening? 

Looking forward to hearing from you regarding this.

Simcha

[dusan]

Hi Uros,
Did you solve your problem? I have the same one and don't know what to do.

Regards,
Dusan