July 1st, 2014: CHN Machine

The CHN machine is used to measure percentages of Carbon, Hydrogen and Nitrogen in a given sample.

I will use this machine to determine percentage values of the C, H and N in the biochar samples that I am working with. Below are the steps to using the CHN machine.

Before the samples can be tested, the machine must be turned on and calibrated (Huan usually helps with this).

After the machine has been heated to the correct temperatures and the gas valves have been opened, blank samples must be runned in the machine. After 3 or 4 blanks have been run and the numbers match up (should be approximately 0 with the blanks), standards are then put into the machine.

To run standard tests the steps are as follows:

– tare scale with the foil cup and foil stand so that the scale is only measuring the addition of standard sample

– measure out between 30-70 mg of standard and put onto foil cup

-record mass and enter onto CHN computer (record in g)

-switch type of sample from blank to ******** and press analyze

– run the stand samples until the values are between the min/max values that Huan has put on the side of the machine to be sure the machine has been calibrated.

To run the tests of the samples you follow the same basic procedures as running standards, however it is a must that you wear gloves and first grind up the samples into very find pieces so that the machine can properly read the test. I measured out about 4 times what one sample would use to grind up so that I would have enough sample to run 3 full tests. To grind the samples I used a motor and grinder and was sure to clean them off between each grinding in order to not contaminate the samples. The other main difference in doing the standards and samples is that you must change the name of the sample to whichever sample I was testing.

After the tests were finished, I copied the information into a file on the computer and then a flash drive that Professor Sills had provided me with. I also am going to copy these files onto the public space on the Bucknell network that has been provided for my research. This can be found at ******

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