0.2 ml injected sample into GC= 200 PPM CH4

Total volume of bottle 125ml =200 x 125/0.2= 125000 PPM per 7g substrate = 17857 PPM per g substrate

Use the Ideal Gas Law: PV = nRT 

P = 1 atm (standard pressure, or use the pressure of your sample) 92.86

V = 0.125 liter (or use the volume of your sample) 

n = the unknown number of moles we're solving for 

R = 0.0821 liter-atm / mole-Kelvin (this is a constant) 

T = 293 K (20 degrees Celsius temperature of sample) 

Rearranging to solve for n, we get n = PV / RT 

n = (1 atm)(0.125 liter) / (0.0821 liter-atm / mole-Kelvin)(293 Kelvin) 

n = 0.0052 moles = 5200 micromoles 

17857 ppm/g: 5200 micromoles x 17857 / 1000000 =  92.86 micromoles /g of substrate