An Extraction Procedure and a Direct Kinetic Method for Cholesterol Compared

Simplex optimization of analytical chemical methods

“…The solvent is composed of a mixture of acetic anhydride and glacial acetic acid. Increasing acetic anhydride concentration is known to improve the intensity of green color in the Liebermann-Burchard reaction (28,36). However, cholesterol is not soluble in acetic anhydride alone; the Carr and Drekter method requires that sufficient glacial acetic acid be added to "extract" the cholesterol (28).…”

“…An increase in the concentration of sulfuric acid increases the rates of conversion of C -*• M and M -* D (28)(29)(30)(31)(32)(33)(34)(35)(36). A greater amount of M is temporarily produced but disappears rapidly.…”

“…The manual colorimetric method of Carr and Drekter (28) for determination of total cholesterol in blood serum was chosen as a benchmark against which to test the experimental designs. The method is based on the Liebermann-Burchard reaction (29, 30) which has been noted by numerous authors for its complexity of response (31)(32)(33)(34)(35)(36). The amounts and proportions of reagents and solvents, color development time, amount of water present, temperature, and the presence of interferences are all factors that have been mentioned for their effects on the intensity and stability of the color formed.…”