This past week has been all about calibration.
You see - the McMurtry Lab at UH Manoa is building a field-deployable mass spectrometer. This is an instrument that is used to measure a large range of molecules that exist in gases. The gases can either be gaseous, or dissolved in a solution like water.
What are we using it for? Next week we'll be headed to Lassen Volcano in northern California to see if we can see any carbon dioxide in a plume, or fumarole, on that active volcano.
But, of course - things don't always go to plan. This instrument is sensitive. Most mass spectrometers are happily housed indoors in nice, climate controlled labs. This mass spec needs to be able to automatically suck in the outside gas, analyze it, and then repeat. A mass spectrometer needs to operate and very low vacuum - usually on the order of 10-8 for a good, clean signal.
So this week, everything is working. The system can run on auto like a champ. We have finished a routine that makes it able to flush itself with a new working sample. What's left to be done is to figure out how to calibrate the gas.
Gases can be measured either by mass or by volume. A 1000 ppm carbon dioxide is 1000 parts per million by volume. As of right now, our mass spec is still seeing more air than signal, which is very perplexing. I hope to figure it out soon!
