Good news: In my recent blank measurements there was just nothing – nada – rien – nix. A week before I found some organic species that should not have been there (obviously) – until I noticed that I had used non-acid washed flasks that I had not rinsed properly. A good sign that my cleaning procedure is doing its job.
I still find column bleeding in the blanks – and in all the samples that I run. That is sometimes a problem for the determination of the peak area – although I observe this overlap rarely. My baseline varies between 2000 and 3000 counts, when scanning a mass range between 15 and 500 amu and a threshold of only 150 counts. So this is not bad at all.
My guess is that the column is coming to the end of its life (at least for the trace work that I do) and I am currently working on a solution for a new column – together with a separate injector port and and switchbox, just before the effluent is entering the MS; the price of the package will decide, if I can implement this solution. It would keep my column clean and would reduce the number of liner changes significantly.
