Chromatography Forum

Good afternoon:

I am new to the forum and hope to get some help from you, guys
Working in the agrochemical Industry, in a pesticides factory. We´ve recently bought and LC-MS in order to avoid cross contamination issues in the plant when moving from one formulation to a different one.
The main problem is we work in the plant with quite significant concentrations (i.e 700 g/L) that we supect our equipment has somehow become contaminated with such concentrations that we are seing huge peaks when injecting blanks. We´ve even bult an special isolated room for the LC-MS but the contamination persists.
Our Agilent technician believes the contamination comes from the mobile phases but we´ve made fresh completely and no signs of improvement. We´ve cleaned the instrument with some IPA, MeOH, ACN and hot water....
I can share some chromatograms if it does help.
Has anyone of you had similar issues with contamination, or can anyone advise how to clean the equipment and which extra careful measures to take when using the LC_MS?
Many thanks!

Hi,

I'm assuming it's a chromatogram peak and not m/z peaks for the sepctrum in MS2 scan mode. Try running a blank in the worklist using no injection for the sample position and compare with injecting a blank and report back. Our autosampler purchased refurbished had quite a bit of contamination that needed to be rinsed out before I could start doing work with MS2 scan. If you're not using the needle rinse, you'll want to going forward.

Regards,
Scott

When troubleshooting LCMS contamination problems, my advice to customers is to acquire an infusion pump and a clean 500uL syringe.
Manually scan the MS while infusing mobile phase at 20uL/min direct to the nebuliser will assist in understanding the source of the contamination.

LCMS is complicated : the key is to firstly bypass the LC.