Can I inject a gas into the Mini GC?

The short answer is: yes.

Here are some important points to remember:
(1) The recommended injection volume for the Mini GC is 0.8 - 1.0 milliliter (mL) of gas.
(2) Vernier does not sell a 1 mL gas-tight syringe.
(3) The maximum outside diameter syringe needle for use with the Mini GC is 0.5 mm. This is a 25 or 26 gauge needle size. See TIL 2050: What size needle does the Mini GC require? for needle specifications.
(4) Make sure there is little to no water vapor in your sample.

If you are interested in buying a syringe for headspace analysis, you can get them from Hamilton. We recommend injecting 1 mL of headspace of a nonpolar sample using a Gastight 1 mL syringe with luer lock attachment to a 26 gauge, pointed needle. These two pieces are available from Hamilton syringes for less than $100 total.