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- Posts: 11
- Joined: Mon Apr 24, 2017 2:08 am
I have a HP5890 series 2 FID that has shown me some decent result with gasoline. In setup, I have a hydrocarbon gas trap on the helium, and am using UHP air and H2. I have used an old school He leak detector to leak check and am reporting leak free. I am using .25mm id columns and configured my gas flows by the manual. I'm having to hit some pretty high pressures to achieve 2ml/min flow rates. I can't recall where I came up with 2ml/min, but thats where i am at.
Initially, I configured with a Zebron semi-volatile column and ran injections of gasoline. I was able to achieve decent peaks. I changed over to restock 5MS-SiL 30m .25mm id column to start my cannabis attempts. These are old stock columns I bought off of eBay (original rubber cap on the column).
I am reading ~9.5 on my output (I can't recall he units, pA?). My signal shows some occasional spikes with values less than +- 0.5 units. I am operating in a residential building with typical dirty power. With my cannabis runs, my peaks are registering very low (~20pA) and I have some drift in my baseline (+- 1 unit). My linear velocity is somewhere around 20 cm/s and I am getting a good solvent peak, but no significant cannabis peaks (thc&CBD/terpenes). I should certainly be getting a significant THC peak w/ cannabis @23+% thc.
My expectation is that if I am loading the column properly, my peaks should be orders of magnitude higher than my baseline. My first thought to getting better peaks would be to operate my split valve in split less mode for a second or so after injection, but the valve is non functional. How would you all recommend going about modifying a method to improve my column loading to achieve better peaks?