Air pollutant concentration measurement technique?

[nachus001]

Hi all:

I'm working in a air pollutant level sensing system, to measure the common air pollutants and their level. I begun with this some months ago (In fact I've taken the others work's in my hands), and used electrochemical gas sensors for low ppm sensing (Up to 50ppm) and with 0.1ppm resolution. But the problem I found is that for the common air pollutants levels to be measured (as stated in the Title 40 CFR part 50, this is O3, CO, SO2, NO2 excluding particulates and lead) the tolerance of the sensor is very high (I calculated more or less a 40% @0.1ppm). Moreover, when the data points are integrated, in the integration period that the CFR states, the result is real nonsense!

So I'm investigated a bit more, and found that what I need to achieve this goal is spectrography, in order to retrieve the pollutant concentration in a given air sample at very low ppm, indeed ppb.

But, now, there are a great variety of spectrographic devices and techniques, and I really don't know what to use for this application.

For example, One of the characteristics of the system is that it must be small and rapidly deployable, even if it's lacking some precission (not too much of course, that's why I rejected the EC sensor approach) and as small as possible. So I looked in the web and went to the Horiba website:

http://www.horiba.com/us/en/scientific/products/oem-components-systems/

Great! it's full of OEM spectroscopy parts. But I don't know exactly what parts do I need to build such a system. I think that it's possible to go the OEM way, since I need to get raw data, to be transmitted to a server and then processed (the datalogger is ready done and working) . But don't know what kind of module I need because there are many kinds of them, for different purposes, and, apparently, there are different approaches for the measuring and detection of the said gasses. I thought I'd need some kind of absorption spectrography for gasses, which implies a light source, a chamber to take samples, a pump and valves. But it's no problem to construct this.

The questions are then, What do you suggest I should do? What is the kind of spectrography technique should I use for the said gasses? From your experience, what is the appropiate measuring setup? Do you know of alternative suppliers of OEM parts for this purpose?


Thanks In advance
Ignacio

 

[MATLABdude]

Welcome to PhysicsForums!

Small, and rapidly deployable... Not quite there yet, but I have friends who were / are working in the field of gas detection / measurement using laser diodes:
http://www.boreal-laser.com/docs/Laser%20Gas%20Detection.pdf

That was applications (look up John Tulip on, e.g. WebofScience or Google Scholar for more academic papers out of his group, and probably a survey paper or two). If you're looking for a primer, try:
http://www.boreal-laser.com/info/tech.htm

Looks like there's something (probably a Springer or Elsevier survey textbook) on Amazon when I Googled for "laser gas sensing"

 

[nachus001]

Thank you Dude:

I saw the Boreal Laser website, but the detectors are suited for gas leakages and are extremely directional. However, it's a valuable resource!

Thank you
Nachus

 

[timmay]

There is a spin off company within the university I work at who are approaching this with a portable UV spectrometer. It's probably outside of the realms of possibility for you but I thought it was an interesting idea.