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- Posts: 9
- Joined: Tue Sep 10, 2019 11:44 pm
I have run into a problem with my Agilent 1260 ELSD where I am receiving an error that the evaporator gas flow rate is exceeding the limit (Error 21). This seems to indicate that the mass flow controller has gone bad so Agilent is recommending an exchange for the ELSD.
However, this error only occurred when I handed the instrument over to R&D to run a new method for a couple of weeks and I just took it back and switched it back over to our method. Talking to R&D, they never saw this problem while operating it and they ran the ELSD using pretty much the same conditions as we do (Evaporator & Nebulizer @30C and Gas Flow Rate @1.60SLM). The main difference with their method is they used a buffered mobile phase of 10mM Ammonium Formate in 95:5 ACN:H2O while we do not (we use 80:20 MeOH:H2O with 0.1% FA each). It sat for a few days between them using it and us taking it back over to run our method. I checked the inlet gas pressure and it is normal, 60 psi, so I don't expect that changed at all over the course of operation.
I think the ELSD may be toast and we will have to do the exchange, but I would like to know what happened to it to cause it to go bad so that it doesn't happen again. Any ideas?