ELSD for multiple components

[hajdaei]

We are currently working on an analysis of several components in a drug product ("deformulation" is the technical term). We are finding it very difficult by ELSD - we are not seeing peaks for several of the compounds.

I am wondering about other experiences with this kind of thing. Is ELSD normally very difficult to do with several analytes of differing properties/polarity/molecular weight? Are issues like drift tube temperature very critical such that they have to be carefully set for each compound?

Please let me know of any successes or failures attempting to use ELSD for several compounds - of differing properties - simultaneously.

Thanks

[XL]

I use ELSD quite often and have found it quite useful. To trouble-shoot, please look into the following aspects:

1. ELSD setting. Depending on manuafacturer and model, the setting will be different. You can find useful information from the manufacturer's website.

2. Mobile phase. The mobile phase should be volatile, and free of non-volatile impurities.

3. The analytes should be non-volatile. Quite a number of pharmaceutical components are volatile, thus can't be detected by ELSD.

I usually put a UV detector between the separation column and the ELSD to get more complete picture of my samples.

Xiaodong Liu

[unmgvar]

what is your ELSD type?
at what conc. are looking at those compounds? maybe too low for the ELSD?

are you running a gradient, if yes then of what? since a few years back ELSDs have function to deal with gradients in order to adjust for the changes in volatility of the mobile phase. wrong setting will create more background noise and more baseline offset and that will effect your chromatography