Table 2. Results of stability of the ICS test.

Days	store in room				store in 4℃
	concentration of ZEN (ng/mL)				concentration of ZEN (ng/mL)
	0	10	15	30	0	10	15	30
1d	─a	─	+b	+	─	─	+	+
2d	─	─	+	+	─	─	+	+
3d	─	─	+	+	─	─	+	+
4d	─	─	+	+	─	─	+	+
5d	─	─	+	+	─	─	+	+
6d	─	─	+	+	─	─	+	+
7d	─	─	+	+	─	─	+	+
14d	─	─	+	+	─	─	+	+
30d	─	─	+	+	─	─	+	+
60d	─	─	─	+	─	─	+	+
90d	─	─	─	+	─	─	+	+
120d	─	─	─	+	─	─	+	+
150d	─	+	ND	─	─	─	+	+
180d	─	ND	─	─	─	─	+	+
210d	─	─	─	─	─	─	+	+
240d	ND	ND	ND	─	─	─	+	+
270d	ND	ND	ND	ND	─	─	+	+
300d	ND	ND	ND	ND	─	─	+	+
330d	ND	ND	ND	ND	─	─	+	+
360d	ND	ND	ND	ND	─	─	+	+
390d	ND	ND	ND	ND	ND	ND	ND	ND

a: Positive result, T line vanished.

b: Negative result, both T line and C line appeared clearly.

ND: Not detected (the limit detection of ZEN is 15 ng/mL).