Finding the Concentration of the Triple Standard

The concentration of the triple standard was very high.  Therefore to find its concentration, we had to dilute the standard gas, measure the concentration of the diluted gas, and then account for the dilution step.

First, we accurately measured the volume of a two 1000 ml flasks.  We massed the flasks, filled them with pure water at room temperature, and then remassed them. We found the volume of one flask to be 1097.7 ml and the other to be 1084.8 ml.

Then we purged the flasks with pure nitrogen at 5 psi for 5 minutes.  The flasks were open to the atmosphere, so they were remained at atmospheric pressure.  We then capped the flasks, removed 500 ul of nitrogen, and added 500 ul of the standard gas.  This essentially diluted the standard by a factor of two thousand.  Here’s a picture of the diluted standards.


the diluted standard

the diluted standard

We injected this diluted standard into the 1.012 ml loop on the valco valve.  We were able to bracket this concentration with the calibration curve.  We then accounted for the dilution step to find the concentration of the triple standard, which we determined to be about 10 ppmv for CF3SF5 and 49 ppmv for SF6.