Table 3.

Recovery, intra- and interday precision and matrix effect (ME) for barbiturates.

	Compound	Concentration (ng/mg)	Average recovery (%)	CV (%)	Precision (CV, %)		ME (%)
					Intraday (n = 6)	Interday (n = 3)
UHPLC condition I	Barbital	0.02	101.9	2.38	2.06	2.72	−1.29
		0.04	91.0	5.10	2.30	3.80
		0.20	99.2	4.96	1.36	4.56
	Phenobarbital	0.02	108.0	1.90	1.24	2.46	−4.12
		0.04	99.3	1.14	0.77	1.29
		0.20	99.8	0.27	1.20	2.46
	Amobarbital	0.02	95.5	5.57	3.39	2.44	−2.83
		0.04	102.8	1.90	3.39	1.97
		0.20	92.6	2.46	2.33	3.16
	Pentobarbital	0.02	95.6	5.31	1.01	4.00	−2.67
		0.04	99.7	4.61	1.89	0.99
		0.20	101.5	1.03	1.24	1.02
	Secobarbital	0.02	117.2	2.21	1.36	3.58	−8.43
		0.04	101.4	2.90	2.56	4.71
		0.20	103.4	3.34	4.75	3.54
	Butalbital	0.02	119.7	2.52	3.42	1.62	−9.05
		0.04	101.3	4.70	2.28	2.02
		0.20	101.3	1.98	2.24	6.07
	Thiopental sodium	0.02	93.7	3.82	3.73	5.21	−4.61
		0.04	106.8	3.91	5.86	1.96
		0.20	107.1	1.69	4.89	2.20
UHPLC condition II	Amobarbital	0.02	101.8	3.44	3.01	1.78	−2.21
		0.04	98.6	2.08	3.46	4.41
		0.20	99.7	1.56	1.05	2.87
	Pentobarbital	0.02	98.5	2.17	2.89	3.09	−3.36
		0.04	96.6	3.39	2.60	2.54
		0.20	102.1	1.65	1.09	2.90

CV: coefficient of variance.