🔬 1. BCG Method (Bromocresol Green)

Most widely used in routine chemistry analyzers.

Principle

Albumin binds to BCG dye in an acidic buffer forming a green-colored complex.

• Absorbance: 600–630 nm (green complex)

• Type: Endpoint reaction (color intensity ∝ albumin concentration)

Advantages

• Very robust

• Strong signal (high sensitivity)

Limitations

• Mild positive bias in some conditions (e.g., high globulins)

🧪 2. BCP Method (Bromocresol Purple)

A more specific albumin method.

Principle

Albumin binds selectively to BCP dye in acidic buffer forming a purple complex.

• Absorbance: 540–550 nm

• Type: Endpoint

Advantages

• Higher specificity than BCG

• Less interference from globulins or acute phase proteins

Limitations

• Slightly lower color intensity

• More common in premium reagent lines