So, the 0.3g are your complete sample and you got 21.02 ppm out of it? What does the rest of your sample consist of? Or did you put in 0.3g NH3 onto the sample and 21.02 ppm stuck?

Please clarify what you mean, otherwise you will get contradictory answers from here as well.

Hi Jürgen Weippert

The sample was 0.3 g throughout the experiment with a NH3 flow of 300ml/min for 50 minutes. I got 21.02 ppm of NH3 adsorbed and then varies from time to time.

As you know, ppm stands for: 21,02 gram NH3 in 1000000 gram of mixture

It is equal to: (21.02/1000000) gram NH3 in 1 gram of mixture

or: 21.02 microgram NH3 in 1 gram of mixture

or: 21.02/17 micromole NH3 in 1 gram of mixture .

Finally, your answer 1.237 micromole/g of mixture (but not "micromole/g of NH3")

Sorry, but that's not correct. ppm is a particle unit, not a mass unit. 21.02ppm means that in one mol of the mixture there are 21.02 nmol NH3, but as long as we don't know the mass of the components with which it is mixed, there is no recalculation possible.

Sorry, but ppm may be ppmv ( by volume), or ppmw (by weight),

in most cases ppm stands for ppmw.

But if not, molar units may be recalculated from the rule (22.4 liter of any gas equal 1 mol)