title: Interference of sodium azide with the quantitation of serum cholesterol: a comparative study.
abstract: Interference of sodium azide (employed widely as a preservative for serum) with six different cholesterol methods and two modified procedures is analyzed and compared. Sodium azide is shown to lower the serum cholesterol values of the iron-cholesterol methods from 5 to 50% at 0.1 g% azide, and from 60 to 95% at 1.0 g% azide concentration, depending on the method employed. This inhibition is independent of serum cholesterol concentration. Increased serum to reagent (v/v) ratio, i.e., increased azide concentration, caused increased depression of serum cholesterol values. Appropriate choice of low serum-to-reagent (v/v) ratio thus decreases the magnitude of the azide interference in the iron-cholesterol reaction to 3-10% for the precipitation procedures, and to 25% for the non-precipitation procedure at 0.1 g% azide concentration in serum.
mesh_terms: D001386:Azides; D002784:Cholesterol / Q000097:blood*; D003124:Colorimetry / Q000379:methods; D005069:Evaluation Studies as Topic; D006801:Humans; D007202:Indicators and Reagents; D007501:Iron
chemical_list: D001386:Azides; D007202:Indicators and Reagents; D002784:Cholesterol; D007501:Iron