Greetings,
I am experiencing band broadening as my analytes pass through a radiochem detector. The volume of the solid (CaF) radiochem cell is 250 uL. I know that as a rule of thumb a detector cell volume should be less than 1/10th the volume of the peak to minimize bandbroadening as the analyte passes through, I am injecting only 30 uL volume. I fear that if I go to a lower volume cell I will lose sensitivity. Does anyone have any experience that they are willing to share.

d:\docs

d:docsrs-calc2.xls rs-calc2.xls (13 k)

Sigh!

OK, the previous message posted the attachment but not the message!

Basically, the observed peak width is the square root of the sums of the squares of the independent contributions to peak broadening (column, detector cell, injector, fittings, etc.). In your situation, it's safe to assume that substantially all the extra-column broadening is due to the cell.

The previous post has a quick-and-dirty spreadsheet that I put together for a troubleshooting class a couple of years ago. You can plug in values for column dimensions, extra-column volume, retention, and selectivity and estimate resolution and observed peak width. If you play around with the numbers a little bit, you'll get a feel for the magnitude of the band-broadening effects. If you have a reasonably big column (e.g., 25-cam x 4.6-mm, you're not losing *that* much.

Hope this helps!

-- Tom Jupille / LC Resources Inc.