Transitioning from Packed to Capillary Column (GC 7890B)

Hi

If you want to configured capillary inlet by removing purge packed inlet then you have to buy complete capillay inlet assy with EPC..

And for this job, need specialty to install and configure it so need local agilent support..

We won't know if a new inlet is needed until trying (with our solvents we are borderline for volume). From what we've been told we may not need a new inlet. Do you have any experience in how the operational procedure changes between a packed and capillary column? 

Find above detail of all type agilent inlets and there use and differences...

Which packed column and detector are you using?  What volume are you injecting? What detection limit do you need?

Thanks all for the engagement! We are currently using a custom glass column. Detector is NPD. We inject 1 mL with our lowest detection limit being 0.002 mg/mL. Do you have any suggestions for trial parameters with the purged packed inlet and HP-5 capillary column? (HP-5: 30m x 0.32mm 0.25 micron) 

Hello Devon, These are good questions and you may have to experiment some to find out what detection limit you can achieve with different hardware configurations.  If you are using a packed column I would think about going to a bigger I.D. column like an HP-5, 30 m x 0.53 mm x 0.88 um, PN 19095J-023.  The 0.53 mm I.D. column will give you more capacity than the 0.32 mm column and will be able to handle larger injection volumes.  If you decide to go to a capillary column I recommend moving to a split/splitless inlet. This will give you complete control over the amount you inject on column.  Each liner has a different capacity as well.  So go to the Agilent GC Calculators page and download our GC calculators.  The vapor volume calculator will allow you to calculate the vapor volume of your solvent and will allow you to calculate the max liquid inject volume for the inlet liner you are using.  That should give you a good start and give you the tools to figure out how much you can inject.  Your peaks will be sharper with capillary columns so you will gain some peak height and sensitivity.  You will have to experiment to determine what your method detection limits will be.

Hi Shannon, thank you for this insight! Aside from potentially decreasing our injection volume, do you recommend changing pressures and temperatures in order to trial a capillary column with our current purged packed inlet? If so, any recommendations on what they should be changed to? (I understand this would have to be fine-tuned depending on our method, but looking for a starting point) 

Hi Shannon, thank you for this insight! Aside from potentially decreasing our injection volume, do you recommend changing pressures and temperatures in order to trial a capillary column with our current purged packed inlet? If so, any recommendations on what they should be changed to? (I understand this would have to be fine-tuned depending on our method, but looking for a starting point) 

With the packed column we currently run at 30 psi, oven temperature 200, inlet temp 240, front detector temp 325. 

After using the vapor volume calculator tool we are at 86% capacity, so there's no way for us to know for sure if the capillary column will work or not without trying. For now I want to understand what parameters to use in order to trial the materials that we currently have. If we are unsuccessful with our current inlet-type and column, we will explore switching to a split/splitless inlet

What is your matrix and which analytes will you be analyzing? I will see if I can find an example?   You will likely have to experiment to get a definite answer.

An example would be great, thank you! The analyte is caffeine, what do you mean by matrix? 

What is the caffeine dissolved in?

Thanks for clarifying. It's a mix but primary solvent is ethyl acetate