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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.

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PNU

PNU, Protein Nitrogen Unit. A measurement of protein concentration, which is analyzed in all lots of aqueous, non-standardized extracts. PNU is derived from the nitrogen content of the extract solution. One milligram of nitrogen is equivalent to 100,000 PNU.

Phenol

A common preservative in allergenic extracts. Phenol possesses bacteriostatic properties, thereby inhibiting bacterial growth. The FDA mandates that all multiple dose vials contain a preservative to ensure sterility. The inclusion of phenol in patient allergy immunotherapy vials allows for an Allergen Extract Exemption in USP 797.