Table 2.

Accuracy and precision for QC samples and lowest calibrator, N=20.

	Lowest Calibrator (1.0 ng/mL)		QC Low (7.5 ng/mL)		QC High (75 ng/mL)
	% RSD	% Error	% RSD	% Error	% RSD	% Error
Fentanyl*	9.5	−7.8	6.6	−2.3	5.1	−4.1
Sufentanil*	11	−6.3	9.8	−7.4	6.5	−4.9
Carfentanil*	14	−8.3	11	−7.4	6.4	−5.9
Alfentanil*	10	−9.1	6.8	−4.4	6.6	−3.6
Lofentanil	16	−4.3	15	−5.6	15	−4.2
α-methyl fentanll	25	−5.0	24	−4.6	19	−7.2
3-methyl fentanil	20	−2.3	21	−5.3	18	−5.3

^*Represents analogs with isotopically labeled matched internal standards.