Sieves work great for separating seed and chaff. I happen to have several sizes of sieves ranging from 1/4" to almost microscopic size. A regular wire kitchen sieve will take care of a lot of the chaff.

I have also done it manually by sprinkling some on a plate and picking the seeds out one by one.

Sometimes putting the seeds in a bowl and gently blowing little puffs of air will send the chaff flying and leave the seeds. Using a gentle shaking motion while blowing will keep the seeds rolling in the bowl while the chaff blows away. This can be tricking depending on the seeds so use with caution or you may blow your seeds away too.

Lastly, just don't get crazy about chaff mixed with seeds. It doesn't hurt anything and if you are trading, just let the trader know that there is some chaff mixed with the seeds.

Actually-even if you don't remove the chaff-mother nature and the elements,and father time will do it for you-as has been done for milleniums,before humans had a thought.Just relax-try one or two,chaff and all.They will still sprout....M