Table 4.

Stability of samples at 4 °C for 1 week.

Nominal Concentration (μg/mL)	Measured Concentration (μg/mL)
	Day 1	Day 8	% Change
In DMEM/F12 cell culture media
0.05	0.050	0.049	1.3%
5	5.02	4.44	11.5%
10	10.19	9.57	6.1%
In fetal placental perfusion media
0.05	0.052	0.048	8.5%
5	4.80	4.45	7.2%
10	10.50	10.53	0.3%