Table IV.

Imprecision and Accuracy of Methadone and Metabolites in Breast Milk as Determined by LC–APCI-MS–MS

	Intraday (n = 5)			Interday (n = 20)
Analyte (%expected)	Concentration	Mean (ng/mL)	Imprecision (ng/mL)	Mean (RSD)	Imprecision (ng/mL)	Accuracy (RSD)
Methadone	20	19.2	14.4	19.6	10.5	98.0
	40	38.9	11.1	40.4	9.2	101.0
	400	401.5	7.9	388.3	12.3	97.0
EDDP	20	18.0	7.8	17.9	8.7	89.0
	40	35.3	5.4	35.8	8.3	90.0
	400	351.7	5.6	367.7	10.5	92.0
EMDP	20	20.1	7.8	20.3	12.4	101.0
	40	42.0	10.0	40.2	10.0	100.0