How to Determine if an Unknown Liquid Is Glycol or Glycerin.

Do you have any refractometer that can tell whether an unknown liquid is glycol or glycerin?

No, unfortunately a refractometer cannot tell the difference between glycol and glycerin. Although we do have refractometers with both glycol and glycerin scales, you must know which fluid you are testing and test it on the correct scale to get an accurate measurement of concentration or freeze point.