Chromatography Forum

When we analyze a liquid using a GC, results are reported at wt%. Is that the same things as %. We do the same thing with ppm, we report it as wtppm.

Thanks

Hi ilawerence,

The answer is "maybe," it depends on how percent is defined in your calculations and your work...ppm, or percent, may be defined on mass basis (w/w), volume basis (v/v) or mass-to-volume (w/v).

Probably the best thing to do is to sit down and review your work...how are you preparing the solutions that you are working with, and what answer(s) are you looking for in the end.

Best Wishes!

It is exactly this kind of confusion which leads to official recommendations that all results be presented in terms of SI units - so mass/mass e.g mg/g, mass/volume e.g. g/l, volume fraction e.g ml/l etc. Then everyone knows exactly what you are reporting when you report a result.

Peter

Agree with Peter completely! And even then, you'll get people who feel that 1 g/L means 1 g of stuff plus 1 L of solvent, while others will feel it means 1 g of stuff made up to a total dissolved volume of 1 L by addition of solvent.
The more explicit you can be when stating how solutions are made, the better.

Very Difficult Not to Agree with the Two Prior Posters to this Thread.

Apologies for Tailgating Once Again!

(This kind of nonsense with units has happened almost everywhere I've ever worked, and it still happens now. Very annoying...!)

I'm so Glad I Bought some Pycnometers for density determinations of liquid and solutions...a small step in the proper direction!