Table 3.

Summary of stability of Methotrexate Under Various Storage Conditions (n=5)

Condition	Concentration (nmol/L)		RSD	RE
	Added	Found	(%)	(%)
Ambient, 2 h	110	109.24±2.40	2.20	−0.71
	440	433.18±14.27	3.29	−1.55
	4400	4401.31±42.48	0.97	0.03
Autosampler, ambient, 24 h	110	108.22±3.60	3.33	−1.62
	440	446.11±18.63	4.18	1.39
	4400	4404.18±152.82	3.47	0.10
Three freeze–thaw	110	112.03±5.61	5.01	1.84
	440	433.41±18.03	4.16	−1.50
	4400	4425.37±167.27	3.78	0.58
−20°C, 42 days	110	107.60±3.09	2.87	−2.18
	440	431.50±9.62	2.23	−1.93
	4400	4437.33±151.12	3.41	0.85