B
Stability at +4 °C, Day 1
QC level [ng/ml]	2	4	20	40
	101	89.9	95.8	100
88.9	91.0	94.1	99.0
96.2	100	102	96.7
89.5	87.8	95.4	88.6
% of nominal concentration	93.9	92.2	96.8	96.1
Imprecision [%CV]	5.8	5.4	3.5	5.2
Stability at +4 °C, Day 3
QC level [ng/ml]	2	4	20	40
	87.3	85.2	105	95.3
Failed	87.8	101	96
101	88.8	89.6	97.5
106	92.2	102	104
% of nominal concentration	98.1	88.5	99.4	98.2
Imprecision [%CV]	9.7	2.9	6.8	4.0
Stability at +4 °C, Day 7
QC level [ng/ml]	2	4	20	40
	94.0	98.5	96.1	110
92.9	96.4	109	109
91.7	96.3	97.9	115
94.7	96.9	99.8	113
% of nominal concentration	93.3	97.0	100.7	111.8
Imprecision [%CV]	1.3	1.0	5.7	2.8