hi all,
i have an Agilnet GC 7890a TCD.
i was wondering how much sample injection is needed for the TCD detector to get a decent peak?
for example, i dont get a good peak when i inject 5 microlitre of CO, but i get clear peaks for the injection volumes over 10.
my column is 2mm Shincarbon ST.
any comment or suggestions are appreciated.
Cheers
Hesam
You must consider the volume in the liner you are using, the solvent in your sample and the injection port. If the expansion volume of your solvent under the temperature conditions is higher than the liner volume you could inject more but you will loose your sample in the valve.
Hi.
On a first glance, 10 uL in column of CO to produce "clear peaks" (I'm assuming this means quantifiable) with a TCD seems pretty good.
If you need better sensitivity change the detector if possible.
Cheers!
I think 10 microlitre may be sufficient for getting clear peaks.
thankyou.
CHeck this application from Restek:
https://www.restek.com/pdfs/PCTS1472-UNV.pdf
They report 5 uL.
The peak high will be dependent on the concentration.
regards,
GB
What is your injection technic? In what matrix do you want to measure the CO?
to Grzegorz Boczkaj : they have used HID which is very sensitive. mine is TCD as mentioned.
Mirkó Páncsics it is a mixture of CO2, CO, H2, Methane. i inject the sample directly to the column. is that what u are asking?
Sandra Teresita Martín del Campo yes i also think about increasing the injection volume to have more CO in the sample.
Hesamoddin Rabiee yes that was the question. I think that the best way was to use a sample injection valve, and injest the sample in gas phase from a sample loop. A 100 uL sample loop is enough for 0,01 quantification limit for CO in non condensable gases.
You're running a 2 mm column and injecting 5 uL? Why? Typical gas-phase injections for a packed column are in the 0.5 to 3 mL range, not uL range. It would be different if you were using a capillary column, but you state that you are not.
Shin carbon is a micropacked column with good capability to separate different gases. As Mark has said, for gaseous samples, the injection volumn should be more than liquid samples. 5 Microlitre sample volumn is too low a quantity to give a good peak. You can increase the injection volumn to atleast 100 microliter and then you can get a decent peak for CO.
R.Girijan Menon Mark Krause
i am nots sure how much CO i will have in my real sample but i know that it would be a tiny amount compared to CO2. if i inject 100ul of CO and get a good peak which i get now anyway, it is not enough for me as CO concentration in the mixture might be around 5%, so 5ul.
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