Total Cholesterol Reagents

🔬 1. CHOD-PAP Method (Gold Standard)

Principle

1. Cholesterol esterase converts cholesterol esters → free cholesterol

2. Cholesterol oxidase converts cholesterol → cholest-4-en-3-one + H₂O₂

3. Peroxidase (POD) uses H₂O₂ to produce a colored dye

   • Common chromogens: 4-AAP, TOOS, DAOS, HDAOS

Absorbance: measured at 500–550 nm depending on chromogen.

What the Reagents Contain

R1 (Buffer / Chromogen)

• Good’s buffer (e.g., PIPES, TES)

• Phenol or TOOS/DAOS derivatives

• Stabilizers & surfactants

• Preservatives

R2 (Enzyme Reagent)

• Cholesterol esterase

• Cholesterol oxidase

• Peroxidase

• Additional surfactants