Separating Ethyl Formate from Ethanol with HP-5 Column

[Incitor]

Hey guys I've been pulling my hair out trying to get a good separation of ethyl formate (analyte) from ethanol (solvent). The problem is that the ethyl formate comes out just after the ethanol peak, and often overlaps.

For the record, I'm using an HP 5890A GC with an 30m hp-5 column with an FID. The helium gas flow rate is about 1.5 ml/min and carrier gas is either 20 or 30 ml/min, I can't remember but I want to say it's 30.

I've tried column temperature ranges from 35 to 75 and inlet temperatures from 95 to 140. Still not really seeing the kind of separation and resolution I'd like to see.

If you guys have any helpful tips I would really appreciate it.

[chromatographer1]

A 0.25mm id column should have a flow of 0.6-1.0 mL/min.

To separate these well, if a slower flow rate doesn't work , or a reduction in sample size (pkwidth) doesn't fix the problem then use a different column, a wax for example.

best wishes,

Rod

[Incitor]

Thanks for the advice. I think I will try reducing the flow rate and see what that does. From there I'll try and increase the split ratio and see what happens.

[KM-USA]

I'm not a huge fan of trying to make a separation work on an already-installed column, either simplicity of not changing out the column, or to save on the cost of a new column.

Ideal is to use the right tool for the job (e.g. a spark plug socket instead of an open end wrench); I understand that the economics do play a big part in the real world however.

[Incitor]

I'm not a huge fan of trying to make a separation work on an already-installed column, either simplicity of not changing out the column, or to save on the cost of a new column.

Ideal is to use the right tool for the job (e.g. a spark plug socket instead of an open end wrench); I understand that the economics do play a big part in the real world however.

Ok, so what column would you recommend for this separation?

[CharapitsaS]

I'm not a huge fan of trying to make a separation work on an already-installed column, either simplicity of not changing out the column, or to save on the cost of a new column.

Ideal is to use the right tool for the job (e.g. a spark plug socket instead of an open end wrench); I understand that the economics do play a big part in the real world however.

Ok, so what column would you recommend for this separation?

We are working for a long time with Restek capillary column Rt-Wax, 60 m long, 0,53 mm internal diameter and phase thickness 1 um. Good separation You may see, for example, here http://www.inp.bsu.by/labs/lar/eis.html

Regards,
Siarhei