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- Posts: 4
- Joined: Wed Jul 15, 2015 2:09 pm
I am a university student looking at the nitrogen fixation rates of soil bacteria, using the acetylene-ethylene reduction assay. I inject acetylene gas into the headspace of gas vials containing bacterial culture. I take samples once a day and measure them in a GC.
The issue is I am not seeing any change in ethylene levels which are very minimal. The acetylene levels seem to be decreasing significantly but this may just be because I am removing some acetylene by taking samples. I am certain that the bacteria are growing and fixing nitrogen as I am growing them in nitrogen free media and have measured growth rate in separate tubes at the same time. It takes about 48 hours for the bacteria to grow exponentially, and reach an absorbance of about 0.100. I have tested for ethylene detection in the GC using a sample of ethylene gas. I do not understand why there seems to be no change in ethylene levels.
I am inexperienced in using GCs and would appreciate any help or suggestions. Thank you!