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- Posts: 7
- Joined: Wed Aug 24, 2011 11:50 pm
I am performing method optimization on a Vecuronium Bromide method that we currently run using Varian instrumentation. To preface, I have zero ELSD experience, but am familiar with RI and UV detection. The method is currently an isocratic run with an evap. temp of 45 C, a 100 uL injection, and a 1 ml/min flow.
The problem we are seeing is that after sufficient equilibration, and injecting a passing system suit, and calibration curve, the check standard, bracketing these injections will pass routinely. We then inject samples (anywhere from 2-6) and the bracketing standard varies wildly by comparison. The obvious answer is that there is something in the samples that is causing this. The method is fully validated, and I believe has sufficient dilution to minimize any matrix effects. Is there a way to help this such as a flush at the end of the method, or a higher evap temp?
I have run environmental samples in my past that have caused problem from being "dirty", but this has been on GC. Adding a bake out to the end of the run or a solvent injection has helped, Im just not sure of what may be the answer and/or likely culprit in this case on ELSD.
Any random tips for decreasing ELSD variability would also be helpful, as this instrumentation could potentially become a larger issue.
The problem we are seeing is that after sufficient equilibration, and injecting a passing system suit, and calibration curve, the check standard, bracketing these injections will pass routinely. We then inject samples (anywhere from 2-6) and the bracketing standard varies wildly by comparison. The obvious answer is that there is something in the samples that is causing this. The method is fully validated, and I believe has sufficient dilution to minimize any matrix effects. Is there a way to help this such as a flush at the end of the method, or a higher evap temp?
I have run environmental samples in my past that have caused problem from being "dirty", but this has been on GC. Adding a bake out to the end of the run or a solvent injection has helped, Im just not sure of what may be the answer and/or likely culprit in this case on ELSD.
Any random tips for decreasing ELSD variability would also be helpful, as this instrumentation could potentially become a larger issue.
