Hello,
In the last several months, I've noticed that the signal in ECD in ambient temperature has increased a little, from 15mV it has reached 28-30mV. During the method's setting up, the signal elevates and finally drops, always remaining around 30-40mV. Suspecting a cell contamination (my samples are food samples) I detached the column end and baked the detector in 450oC and although the signal dropped to 13mV, when I connected the column, the signal rose again. So I trimmed the column and conditioned it several times but nothing changed in the signal. I even purchased a new column (the other one was 3+ years old) but signal still remains elevated, especially when the ECD temperature is starting to reach the method's settings, it goes up to 800mV and then drops again to 30mV. What would you propose?
An air leak can result in noise in ECD and detectors.
Also make sure your gas filters (you DO have carrier and makeup gas filters, right? ) are clean and working. In the past couple of years I have had more cases of contaminated gas cylinders than in the previous 20 combined.
Use ultra pure gases and moreover purging of column as well as conditioning or equilibration of the column. I mean decontaminate. Inject some reference after doing conditioning of the column. Use precolumn if possible.
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