Super high barium contamination?
Hello CyTOFers,
My CyTOF is currently somewhat unhappy after running some clinical tumor samples. I ran one sample last Thursday, after which I had massive barium contamination of the instrument (Ba138 duals well over 1 million while running diH20). It was very difficult to get rid of, but after troubleshooting with tech support and alternating wash solution and water for several hours I finally got my Ba background back down to normal levels. Today I ran another tumor sample (different patient, different kind of tumor) and now I'm back in the same situation - sky high barium levels while running diH20.
So this brings me to my 2 questions:
1) How best to clean the instrument? I'm surprised at how "sticky" this contamination seems to be. I noticed that the levels would periodically start to come down while running diH20, but another round of wash solution would cause a new spike in the levels, which makes it seem like more was being liberated from the tubing with each wash.
2) What might be the source? I've seen samples before that were washed in Ba-containing buffers and in those cases it seemed like all the cells were somewhat high for barium. The situation in this case seems a little more unusual: I wasn't specifically collecting data for the 138Ba channel, but I do see high background staining in In115, Xe131, Cs133 Ce140 (all channels that did not contain antibody and also in Sm154, where Ba138 oxides would presumably appear (see attached PDF). However, most of this background is present in the non-CD45, DNA-negative fraction. Have others seen anything like this? Any thoughts on what's going on and how to avoid it in the future? I suspect it's something originating from the pathology suite where the tissues are being collected from but I'm not sure.
My CyTOF is currently somewhat unhappy after running some clinical tumor samples. I ran one sample last Thursday, after which I had massive barium contamination of the instrument (Ba138 duals well over 1 million while running diH20). It was very difficult to get rid of, but after troubleshooting with tech support and alternating wash solution and water for several hours I finally got my Ba background back down to normal levels. Today I ran another tumor sample (different patient, different kind of tumor) and now I'm back in the same situation - sky high barium levels while running diH20.
So this brings me to my 2 questions:
1) How best to clean the instrument? I'm surprised at how "sticky" this contamination seems to be. I noticed that the levels would periodically start to come down while running diH20, but another round of wash solution would cause a new spike in the levels, which makes it seem like more was being liberated from the tubing with each wash.
2) What might be the source? I've seen samples before that were washed in Ba-containing buffers and in those cases it seemed like all the cells were somewhat high for barium. The situation in this case seems a little more unusual: I wasn't specifically collecting data for the 138Ba channel, but I do see high background staining in In115, Xe131, Cs133 Ce140 (all channels that did not contain antibody and also in Sm154, where Ba138 oxides would presumably appear (see attached PDF). However, most of this background is present in the non-CD45, DNA-negative fraction. Have others seen anything like this? Any thoughts on what's going on and how to avoid it in the future? I suspect it's something originating from the pathology suite where the tissues are being collected from but I'm not sure.
Adeeb Rahman
Icahn School of Medicine at Mount Sinai, NYC
Icahn School of Medicine at Mount Sinai, NYC