Table 1.

Comparison of extraction efficiency with or without the use of surfactant in extraction buffer

Years in storage1	Surfactant2 added to standard extraction buffer	% Extraction efficiency3
		160μg/ml4	40μg/ml4	10μg/ml4
0 (Reference)5	None	72.9	45.9	53.9
1	None	58.4	62.1	67.4
2	None	48.0	34.1	22.4
3	None	24.1	15.7	4.5
3	SDS	100	100	100
3	CPC	100	100	ND6

¹Number of years vaccine formulations stored at 2-8°C;

²30 mM SDS (sodium dodecyl sulfate) or 20 mM CPC (cetylpyridinium chloride) in extraction buffer (0.60 M citrate, 0.55 M phosphate, pH 8.5);

³Extraction efficiency = (intensity of all bands of test sample/ intensity of all bands of reference bulk antigen sample) × 100;

⁴Formulation from which protein was extracted;

⁵Reference was prepared freshly

⁶Not determined.