APPENDIX A

After the headspace sample vial has been in the oven for 30 min, remove the vial and inject the sample into either the GC3 or NGA gas chromatograph. Inject the vacutainer as soon as possible after collection.

The overall sequence for the operation is to set up the correct sample identifier (ID), run the headspace sample (vacutainer) on either GC3 or NGA, look at the chromatographic trace and correct it if necessary, print a report file, and send the data to the Janus database (see "Appendix B").

At the HP ChemStation computer, select the correct GC for analysis by toggling between the two open programs, GC3 (online) and NGA (online), on the command bar.

The procedure to analyze a sample is almost the same for GC3 and NGA. Proceed as follows:

1. Make sure the Method and Run Control windows of the HP ChemStation software are open. In the upper menu, select Run Control and then select Sample Info. This will bring up the screen to enter the sample ID and file names.
2. Change the file name (Signal 1) to the appropriate name, for example, "1H5HS.D" for Core 1, Section 5, headspace sample, or "1H5VAC.D" for Core 1, Section 5, vacutainer sample. Enter either H, X or R, depending on the coring technique.
3. Type the sample ID in the comment field in the following format: "1751075A1H5W0.0-5.0HS" for headspace analysis or "1751075A1H5W0.0-5.0VAC" for vacutainer analysis. These numbers and letters represent the leg (175), site and hole (1075A), core and section (1H-5), working half of the core (W), sampled interval (0.0-5.0 cm), and type of sample (HS or VAC).
4. Click on OK.
5. Inject 5 mL of headspace gas while keeping the flow control between 30 and 40 units, and hit the START button on the GC.

When the GC run is done, the analysis must be checked for accuracy. First, check the numbers on the screen printout, then CLOSE the printout and go to the View menu and select Data Analysis to access the Data Analysis window and look at the GC chromatogram. To modify the peak integration, first verify that the software is in integration mode and not calibration mode, and then reintegrate using the following four buttons:

1. The zoom in and out button, to enlarge or reduce a chosen chromatogram.
2. The X button, to delete chosen peak area integration information.
3. The integral button, to reintegrate a peak area. To do so, first delete the peak (using the X button) then use the mouse and draw a new baseline. When the mouse is released, the peak is automatically integrated.
4. The split peak button, used to split a double peak at the valley.

After correcting the chromatogram, go to the Report menu and select Print Report. The report will print on the screen. From the report, manually write down the values for C₁ to C₃ on the gas analysis clipboard. At a later date, these values can be used to be entered in an Excel spreadsheet and worked on at your leisure.

For NGA analysis, proceed as described above while performing the additional step of checking both the TCD and FID chromatograms, separately. To do so, in the Data Analysis window under the File menu, select the last file run, making sure to select only one signal type, either TCD or FID, and reintegrate the chromatogram for a particular signal if needed. Print the report.

If a peak of interest has not been integrated, its retention time may have shifted. Go into calibration mode (accessed by clicking on the Balance button in the Data Analysis window) and change the retention time of the peak to the new appropriate retention time by typing its new value in the calibration table. DO NOT use any of the calibration buttons!

Once a report has been printed on the screen, the data is usually ready to be sent to the Janus database. See "Appendix B".