Simultaneous Quantification of Methotrexate and Its Metabolite 7-Hydroxy-Methotrexate in Human Plasma for Therapeutic Drug Monitoring

Table 3

Intraday and interday precision and accuracy of MTX and 7-OH-MTX in human plasma (n=5).

Analyte	Nominal concentration; (ng/mL)	Intra-day(n = 5)			Inter-day(n = 15)
		Measured concentration; (ng/mL)	Precision; (RSD%)	Accuracy; (RE%)	Measured concentration; (ng/mL)	Precision; (RSD%)	Accuracy; (RE%)
MTX	10	9.48 ± 0.23	2.47	-5.22	9.30 ± 0.32	3.41	-7.05
	500	514.84 ± 4.56	0.89	2.97	515.67 ± 9.49	1.84	3.13
	5000	5265.35 ± 92.88	1.76	5.31	5305.42 ± 118.95	2.24	6.11
7-OH-MTX	10	9.69 ± 0.66	6.86	-3.15	9.70 ± 0.62	6.40	-3.04
	500	456.43 ± 8.69	1.90	-8.71	469.16 ± 14.98	3.19	-6.17
	5000	4772.84 ± 267.84	5.61	-4.54	4772.93 ± 189.12	3.96	-4.54