Hey there, everyone!!
I have a problem, I use a Shimadzu UPLC with a API 4500 ABSciex detector, and everytime I inject the system suitability test, the areas of my molecules (analite and internal standard) decrease with every injection.
Last time, the analite area went fron 1 200 000 cps to 400 000 cps in the 10th injection, and the same with the IS (from 880 000 cps to 300 000) but the area ratio remain mostly the same.
But when I work without a column, I don't have that problem. I've worked before with the same molecules I didn't had that problem.
I've change everything: Column, lines, capillar. I've clean everything in the autosampler and in the MS font.
Do anyone of you have an idea of what's going on???
Thanks so mucho for your help.