Hi ICP users.
I have a question about a possible (suspected) source of Zn contamination.
I am using a CEM SPD microwave system for sample prep and I am obliged to use a magnetic stirring bar in every quartz microwave vessel. For a long time now I have problems with random high Zn counts. A duplo measurement (separate prep with different vessels and stirring bars) can vary from <0.05 to 10 ppm Zn.
My question is this: can the material of the magnetic stirring bars be responsible for Zn contamination? I never analyse samples with very high Zn content. My quartz vessels are cleaned an checked. It is a mystery to me.
Hope one of you can give me some advice.