Table 4.

Shelf life of ELISA assay at 4°C and -20°C

	4°C		-20°C
	Positive Control (mean+SD)	Negative Control (mean+SD)	Positive Control (mean+SD)	Negative Control (mean+SD)
One Month	0.962 ± 0.037	0.168 ± 0.009	0.898 ± 0.058	0.155 ± 0.061
Two Months	0.934 ± 0.041	0.155 ± 0.014	0.845 ± 0.025	0.147 ± 0.039
Three Months	0.878 ± 0.014	0.145 ± 0.023	0.797 ± 0.006	0.115 ± 0.011
Four Months	0.863 ± 0.023	0.127 ± 0.008	0.752 ± 0.009	0.104 ± 0.008
Five Months	0.856 ± 0.005	0.139 ± 0.012	0.793 ± 0.052	0.113 ± 0.043
Six Months	0.832 ± 0.034	0.143 ± 0.051	0.721 ± 0.048	0.133 ± 0.029