We have an Agilent 1290 Infinity with a 1260 Bin Pump Clin. Ed. K1312B as part of our LC for an LC/MS QQQ system.
We ran Urine samples in our tox lab and have been seeing bad chromatography. On Masshunter quantitative analysis software, this is what we have been seeing:
whereas this is something like what we need to be seeing:
Actually these are both screenshots from the same batch. All of our compounds have peaks like the first screenshot except for diphenhydramine which looks like the second
The column is nearing its half-life as far as amount of samples that we have put through it. I have noticed that the Binary Pump Ripple % is fluctuating pretty dramatically between 0.12% - 1.46% while running mobile phase at 0.5 ml/min. It will not stabilize which makes me think something is wrong at it is why the chromatography is so messed up given the column age is still considered to be good. A little over a month ago all the parts for our binary pump were replaced and more recently the parts for our HiP sampler were also changed out except for the needle due to an issue we had with our binary pump pressure maxing out which has been resolved (by changing out parts for HiP sampler).
any troubleshooting suggestions or ideas related to this?