Hi all, actually im trying to develop a method to measure moss microbial biomass by substrate-induced respiration (the production of Co2). My problem is when I try to do a blank by injecting air (500ul like my simple), the area that I get does not match with the concentration of CO2 in the atmosphere. The ares that i get is around 3000 uV*s for my standard (1000ppm), 1000 uV*s for my simple and 150 uV*s for the air. My measures of CO2 are made by GC-TCD with a porapack column.
Thank you
Stevan
What is your carrier gas?
Generally you need to make a cal8bration curve using a standard mixture of CO2. You cann't calculate it from normalization.
Regards
GB
My carrier gaz is He (gaz flow 10ml/min). Actually i'm using a single point calibration to measure my simple but i'm trying to figure it out how to do my calibration curbe with only one standard mixture at 1000ppm (0,1 mol % in N2). My idea is to use different volumes and use PV=nRT to calculate n or to diluate my standard with pure N2.
BUT my the problem is the area that I get with my blank does not make any sens with the average atmospheric CO2 concentration.
Stevan Roué
Yes. The calibration mixtures can be made by dillution of the primary mixtures. Supelco provide proper gas tight bags for this purpose. The volume injected to GC should be generally constant.
Can you post a chromatogram for blank sample (atoms. air) with the peak integration ?
What is your stat. phase?
Regards
GB
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