Table 2.

Accuracy and precision for analysis of spiked QC samples and authentic hair QC samples

Sample type		Spiked QC						Authentic hair QC samples*
		Intraday			Interday			Intraday		Interday
Drug	Concentration/Patient ID	L	M	H	L	M	H	A	B	A	B
Efavirenz	Spiked Conc. (ng/mg hair)	0.150	1.00	14.0	0.150	1.00	14.0
	Measured Conc. (ng/mg hair)	0.149	1.05	12.4	0.164	1.05	13.9		11		9.8
	Accuracy (%)	99.1	105	88.6	110	105	99.4
	CV (%)	5.4	8.1	9.6	12	6.5	11		4.3		7.7
	n	6	6	6	12	12	12		5		16
Lopinavir	Spiked Conc. (ng/mg hair)	0.150	1.00	14.0	0.150	1.00	14.0
	Measured Conc. (ng/mg hair)	0.149	1.00	13.7	0.165	1.09	13.5	3.1		3.0
	Accuracy (%)	99.1	99.8	97.9	110	109	96.3
	CV (%)	4.3	2.8	5.5	15	11	9.2	13		9.8
	n	6	6	6	12	12	12	6		16
Ritonavir	Spiked Conc. (ng/mg hair)	0.0300	0.200	2.80	0.0300	0.200	2.80
	Measured Conc. (ng/mg hair)	0.0294	0.188	2.72	0.0312	0.196	2.79	0.62		0.66
	Accuracy (%)	98.0	93.8	97.0	104	97.8	99.6
	CV (%)	6.1	3.1	3.6	12	5.8	4.3	9.2		8.9
	n	6	6	6	12	12	12	6		16

^*Authentic hair QC samples were prepared from pooled human hair samples from patients receiving antiretroviral therapy.