Precise H2 and CH4 sensor

I am looking for a precise H2 and CH4 sensor. There is a lot of combined gas sensors (a wide range of flamable gases) but anyone here knows a good one to detect the ppm of H2 and the ppm of CH4 inside a bottle with arduino?

Thanks!

Could you provide a list you have tried / studied allready?

update
Is your goal to detect leakage or an “open air” measurements?

Price indication?

Hi, thanks robtillaart

1) I have 2 http://www.cooking-hacks.com/index.php/shop/sensors/mq8-h2.html?___store=es&___from_store=en sensors from that series, MQ-7, MQ-2, etc. Those cheap sensors can detect ch4 and h2, but as a global value combined with other flamable gases so maybe if you get a bunch of those sensors with different sensibilities to h2 and ch4 you can make an estimation about level of h2 and ch4...

2) My goal is to detect the concentration of H2 and CH4 inside a bottle (with bacterias "eating" waste)

3) Price: From 10 to 100 usd per sensor

Any advice?

No real advice so I googled for H2 and found this (hydrogen sensor review) - http://www.insistec.net/files/2_FIS.pdf (overview) - http://www.fisinc.co.jp/Enew051111/products/SpecE/ESB1900.pdf (H2) They have evaluation modules ...

and a PDF from Nasa with a scheme: - http://www.hydrogenresearch.org/NRM_Nov05/UF-Lin-Wireless%20Hydrogen%20Sensor-Nov05.pdf

out of your pricerange but maybe they have eval kits too? - http://www.kebaili.com/pd_khs100.cfm