TITLE: Measuring CN content in leaf samples using Elementar Vario MICRO Cube
AUTHORS: Jocelyne Ayotte, Xavier Guilbeault-Mayers, Etienne Laliberté

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block"><span>Here we describe the standardised protocol used by the </span><a style = "text-decoration:underline;color:blue;cursor:pointer;"><span style = ":;">Canadian Airborne Biodiversity Observatory</span></a><span> (CABO) to measure CN content in leaf samples, using the Elementar Vario MICRO Cube. </span></div></div>

[STEPS]
?. [Weighing samples and boat preparation]
With a microbalance, put 7 mg (+/-0.2mg) of sample in a tin boat.
?. [Weighing samples and boat preparation]
With a microbalance, put 2 mg (+/-0.2mg) of acetanilide in a tin boat.  With tweezers, gently and carefully close the boat. Using the pressing tool, slowly press the boat to remove any remaining air. Weigh.
Calculate 4 acetanilid standards (for instrument conditioning) + 1 acetanilid standard for each 10 samples.
?. [Instrument preparation ]
Check gaz pressure on manometers. Helium should be 1.2 bar, oxygen should be 2 bar.
?. [Instrument preparation ]
Launch Variomicroselect software. There is no password.Click OK.
?. [Instrument preparation ]
On main screen, check if combustion tube temperature is 950°C and reduction tube is 550°C.
If it is in blue and flashing, it means it is heating up and will reach correct temperatures after few minutes.
If not, you can modify by clicking on Options> Settings>Parameters… and change manually the temperatures.
?. [Instrument preparation ]
On main screen, check the meter flow: TCD should be 200 mL/min; helium should be 200 mL/min; oxygen should be 13 mL/min.
?. [Weighing samples and boat preparation]
With tweezers, gently and carefully close the boat. Using the pressing tool, slowly press the boat to remove any remaining air.
?. [Weighing samples and boat preparation]
Weigh again and note. You will use this in the software before starting the analysis (see step 22).
Prepare all your samples the same way. Prepared samples should be placed in 24-well plates and stored in a dessicator while waiting for the analysis to get started.
?. [Instrument preparation ]
On main screen, have a look on general components by clicking on Maintenance.
If some components are in orange, see with the lab manager if you need to perform a maintenance.
?. [Instrument preparation ]
Open the front door of the Vario MICRO Cube. If the drying tube is mostly white, close the front door and go ahead with next step.
If the drying tube is 2/3 blue, contact the lab manager for a maintenance.
?. [Leak test]
Click on Option -> Diagnostics -> Rough leak test
?. [Leak test]
A window will open, saying to wait until columns are cooled. Press OK.
?. [Leak test]
After 10 minutes, the window will show «Leak test passed» or «Leak test failed». Click Cancel.
If the leak test has failed, see the lab manager.
?. [Conditioning the instrument]
On main screen, write in the table, on rows 1 to 6: Weight (mg): 100Name: MTMethod: Blank without O2
?. [Leak test]
Click Yes
?. [Leak test]
Wait for few minutes until the ads. column temperature is below 30°C and then press Start.
?. [Conditioning the instrument]
Press green button to start the analysis.
The results (N Area and C Area) should be below 100 after few analysis. If it is not the case, contact the lab manager.
?. [Conditioning the instrument]
On row 7 and 8, write: Weight (mg): put the weight of 2 acetanilid boats, prepared in step 4. Name: RunInMethod: 2mgChem70s
?. [Conditioning the instrument]
On row 9 and 10, write:Weight (mg):  100Name: BlankMethod: Blank with O2
?. [Set carousel position]
Go to System --> Carousel position
?. [Conditioning the instrument]
On row 11 and 12, write:Weight (mg):  put the weight of 2 acetanilid boats, prepared in step 4. Name: acetanilidMethod: 2mgChem70s
?. [Conditioning the instrument]
On rows 13 to 23, write: Weight (mg):  put the weight of prepared boats (see steps 1-3). Name: Sample name (cover of sample bottle)Method: 9mgPlant90s
?. [Conditioning the instrument]
On row 24, write: Weight (mg):  100Name: BlankMethod: Blank with O2
Many series can be run in the same day. Between 2 series of 10 samples, put 2 blanks (Blank with O2) and 1 acetanilid (2mgChem70s). The last row should be a blank.
?. [Conditioning the instrument]
Put prepared boats in the carousel. Numbers from carousel holes are corresponding to the software rows. Leave carousel hole empty when corresponding to a blank. Put back the carousel cover.
?. [Conditioning the instrument]
Press green button to start the analysis.
?. [Saving data & shut down the instrument]
Go to File --> Save as
?. [Saving data & shut down the instrument]
Export data:Go to File --> Export/Import --> Export sheet data (for Excel)...
?. [Set carousel position]
Click on All samples removed from the carouseland choose Reference run
?. [Saving data & shut down the instrument]
Write the date (YYYY-MM-DD) and name of the project or student and press Save.
?. [Saving data & shut down the instrument]
And then select Labo Laliberté and the project/student. Press Enregistrer.
?. [Saving data & shut down the instrument]
Make sure the instrument is on sleeping mode before leaving the lab. Have a look at the bottom of the screen.
To put the instrument on sleeping mode, click on the moon on main screenand on Sleep now...
?. [Leak test]
Select Confirm actions...  Click on Close and then Finish.