Glossary < Extractopedia

Home  >  Glossary

The glossary contains definitions and explanations of industry-specific and scientific terminology used within Extractopedia. Click one of the letters above to find terms beginning with that letter.

A B C D E F G H I L M N P R S W

Wheal

The itchy, raised bump induced by the histamine response during skin testing. The size of the wheal can be recorded to indicate the outcome of the skin testing results.

W/V

w/v, weight to volume. A ratio of the weight of dry raw material per volume of extracting fluid, expressed in grams per mL or kg per L. For example, 1:10 w/v implies that one gram of dry allergenic material (e.g. pollen) was extracted in 10 mL of extracting solution. A 1:20 w/v extract is half the concentration of a 1:10 w/v extract, since the same amount of allergenic source material was extracted in twice the volume of extracting solution. w/v designation is used as a rough gauge of potency in non-standardized extracts.