How do I convert ppm to mcg? I need to know if 4ppm of Cyanocobalamin is more or less than 100mcg of the same substance, both in liquid form.
Ppm is the ratio of one thing mixed (dilutely) in another. If you have 25 or more grams of total mixture AND it is 4 ppm of Cyanocobalamin, then you have 100 or more mcg
If you don't know the total amount of mixture, the question has no answer.
Of course to add confusion, ppm may be a ratio of mass/mass, mass/volume, volume/volume, or mole fraction ratios. If you don't know the basis of the ppm calculation, again it has no meaning. What kind of ppm.