tcd's

[soak]

Hi folks,

I'm been using GC's for a while, but have recently been given the task of setting up a TCD which I haven't used before. I'm running it with He carrier and two mole sieve columns. Could anyone give me any ideas of any of the working parameters I should use to get best results when analysing N2, CO2, O2, N2O????

Cheers

S

[chromatographer1]

You did not say if you have a traditional hot wire, a thermister, or a HP-type µTCD detector.

Are you using a PLOT column, a micropacked, or a packed column system?

A little more information would be helpful.

In general if you have a dual TCD keep your flow rates on the same order of magnitude and temperatures higher than the condensation temperature of your analytes injected onto your column.

[soak]

I'm using a traditional hot wire with a packed column

[chromatographer1]

flows in the 20-40 cc/min are fine for 1/8" OD columns, 5 to 20 cc/min for 1/16" OD micropacked columns.

Minimize deadspace in your plumbing, use minimum makeup gas at your detectors (assuming you have a column connected to each).

Keep your flows reasonably balanced (so you can zero your baseline).

Use a 150°C detector temperature so no moisture problems. Raising your wire temperature will increase your noise but increase your sensitivity.

If you condition your mole sieve columns in the oven, disconnect columns from detector and close off detectors but leave makeup gas flowing. Turn wire temp down while detector is blocked off during conditioning.

Condition mole sieve columns with a very slow temperature ramp (as slow as possible, holding temperature for a few hours at each step of 50°C going from 100° to 250°C. Keep at 250°C for a minimum of 18 hours and cool down to ambient @ 2° or 4° per min.

Good luck

Rod