C
Stability at -20 °C, Day 3
QC level [ng/ml]	2	4	20	40
	87.3	98.7	111	111
93.5	89.6	108	105
89.5	91.5	107	112
88.2	99.1	108	92.4
% of nominal concentration	89.6	94.7	108.5	105.1
Imprecision [%CV]	2.7	4.9	1.7	9.0
Stability at -20 °C, Day 7
QC level [ng/ml]	2	4	20	40
	96.5	98.7	102	109
94.8	94.6	114	106
95.5	102	98.1	108
107	99.5	115	105
% of nominal concentration	98.5	98.7	107.3	107
Imprecision [%CV]	5.7	3.1	8.5	1.8
Stability at -20 °C, Day 30
QC level [ng/ml]	2	4	20	40
	82.3	83.1	90.4	93.2
87.9	85.8	85.3	97.9
85.7	88.6	98.3	98.0
92.0	95.6	110	103
% of nominal concentration	87.0	88.3	96.0	98.0
Imprecision [%CV]	4.1	5.4	10.8	4.0