Table 2.

Intra- and inter-assay imprecision and accuracy for morphine, morphine-3-β-glucuronide, morphine-6-β-glucuronide, hydromorphone and normorphine QC levels.

QC Level	Intra-assay imprecision and accuracy (n=20)				Inter-assay imprecision and accuracy (n=20)
	Mean (ng/mL)	SD	%CV	%BIAS	Mean (ng/mL)	SD	%CV	%BIAS
Morphine
Low	5.64	0.21	3.6	2.5	4.98	0.36	7.3	−9.4
Mid	76.91	1.80	2.3	2.5	82.01	2.30	2.8	9.3
High	883.14	22.30	2.5	3.9	905.00	39.10	4.3	6.5
Morphine-3-β-Glucuronide
Low	5.57	0.32	5.8	1.3	4.83	0.27	5.7	−12.2
Mid	75.35	2.52	3.3	0.5	77.58	3.98	5.1	3.4
High	840.81	34.57	4.1	−1.1	815.73	58.99	7.2	−4.0
Morphine-6-β-Glucuronide
Low	5.55	0.32	5.8	0.9	4.72	0.26	5.6	−14.2
Mid	76.46	1.93	2.5	1.9	74.46	2.95	4.0	−0.7
High	855.21	18.16	2.1	0.6	859.18	41.51	4.8	1.1
Hydromorphone
Low	5.57	0.19	3.4	1.3	5.58	0.33	5.9	1.4
Mid	82.06	2.37	2.9	9.4	75.12	3.20	4.3	0.2
High	866.43	16.35	1.9	1.9	929.45	22.61	2.4	9.3
Normorphine
Low	5.42	0.38	7.0	−1.5	5.60	0.76	13.5	1.8
Mid	86.76	2.41	2.8	15.7	81.26	4.35	5.4	8.3
High	852.14	28.50	3.3	0.3	909.96	44.47	4.9	7.0