Internal & external audits: first-, second-, and third-party audits. 1  A first-party audit is performed within an organization to measure its strengths and weaknesses against its own procedures or methods and/or against external standards adopted by (voluntary) or imposed on (mandatory) the organization.
Precursor (chemistry) In chemistry, a precursor is a compound that participates in a chemical reaction that produces another compound. In biochemistry, the term precursor often refers more specifically to a chemical compound preceding another in a metabolic pathway, such as a protein precursor. 1 Illicit drug precursors.
2. a person, animal, or thing regarded as a harbinger: The first robin is a precursor of spring. 3. a chemical that is transformed into another compound, as in the course of a chemical reaction, and therefore precedes that compound in the synthetic pathway: Cholesterol is a precursor of testosterone. 4. a cell or tissue that gives rise to a variant, specialized, or more mature form.