Chromatography Forum

Can we directly inject fermentation broth in CP Wax 52 CB? I have seen in articles that its equivalent columns like BP-20, DB-Wax have been used for direct injection but I haven't found a reference for this specific column.

If yes, can anyone suggest a suitable method for analysis?

If you have to inject nasty samples like that I'd recommend getting a column union and putting at least 2m of silica tubing as a retention gap to spare the analytical column and either rinse or change it regularly. You are also going to go through a ton of lines and be doing inlet matenance frequently.

What precisely are you looking for, fatty acids, esters? I'd do either a solvent extraction, headspace-SPME, or a derivatization and solvent extraction (chloroformates).

MSCHemist!

I am doing solvent (alcohol and ketone) analysis of the fermentation broth. If I go through solvent extraction, the efficiency of solvent and procedure limits the amount recovered and I end up getting less concentration than actually present in my sample.

What can be done to alleviate this problem?

Have you thought about equilibrium headspace analysis ?

Peter

Peter!

Please elaborate about equilibrium head space analysis.

Basically you put sample into a vial, cap it, equilibriate it and analyse a sample of the headspace, which contains volatile analytes in proportion to their concentration in the sample, but does not contain non-volatile components that mess up columns and inlets.

Google it.

Peter

I'd recommend Headspace SPME.

Materials
20973 Restek Liner (cheap)
Manual SPME holder
2cm Carboxen:PDMS/DVB fiber
22ml tall headspace tubes and caps
very small stir bars
Ring stand
heat/stir plate
water bath
thermometer
clamp holder for the vial.


Put some sample in a headspace tube and saturate with NaCl and dilute with waer for a total volume of 1-4ml
Inubate with vigrous stiring in the water bath for 15min
Insert fiber into tube and incubate fiber with head space for 30 min
Remove fiber
Insert fiber into GC inlet and allow it to desorb into the system for 1 minute at 260 deg C (spliteless to 2:1 Split)
start run
Remove Fiber and put into another inlet not being used to regenerate fiber

I do SPME all the time and get excelent recover of alchohols and ketones.

My game is aroma and flavor. I use headspace SPME almost exclusively. The only place I see that it doesn't measure up is for very light materials coming out of condensed phases. I have found good success with light materials in expanded gases (particularly CO2). I agree with MSChemist. SPME is a wonderful technique.

I'd recommend Headspace SPME.

Materials
20973 Restek Liner (cheap)
Manual SPME holder
2cm Carboxen:PDMS/DVB fiber
22ml tall headspace tubes and caps
very small stir bars
Ring stand
heat/stir plate
water bath
thermometer
clamp holder for the vial.


Put some sample in a headspace tube and saturate with NaCl and dilute with waer for a total volume of 1-4ml
Inubate with vigrous stiring in the water bath for 15min
Insert fiber into tube and incubate fiber with head space for 30 min
Remove fiber
Insert fiber into GC inlet and allow it to desorb into the system for 1 minute at 260 deg C (spliteless to 2:1 Split)
start run
Remove Fiber and put into another inlet not being used to regenerate fiber

I do SPME all the time and get excelent recover of alchohols and ketones.

Thanks MSCHemist! I will try it

My game is aroma and flavor. I use headspace SPME almost exclusively. The only place I see that it doesn't measure up is for very light materials coming out of condensed phases. I have found good success with light materials in expanded gases (particularly CO2). I agree with MSChemist. SPME is a wonderful technique.

rb6banjo!

Thanks for your response.