Table 3.

Matrix factors for analyzing lopinavir, ritonavir and efavirenz in human hair

	Matrix factor			IS normalized matrix factor
Hair matrix	Lopinavir	Ritonavir	Efavirenz	Lopinavir	Ritonavir	Efavirenz
Lot A	0.91	0.82	0.97	0.99	0.97	0.95
Lot B	1.02	0.96	0.91	0.99	0.95	0.94
Lot C	1.05	1.05	1.00	0.99	0.94	0.97
Lot D	1.00	0.91	1.00	0.92	0.93	0.92
Lot E	0.98	1.02	0.93	0.92	0.91	0.86
Lot G	1.06	1.06	1.02	0.95	0.93	0.96
Mean	1.00	0.97	0.97	0.96	0.94	0.93
SD	0.051	0.083	0.037	0.030	0.020	0.035
CV(%)	5.1	8.6	3.9	3.1	2.1	3.8

The matrix factor (MF) was measured for each lot of hair samples at medium concentration in duplicate.

MF = (the analyte peak area in hair matrix)/(the analyte peak area in pure solution).

IS normalized MF = (the analyte vs IS peak area ratio in hair matrix)/(the analyte vs IS peak area ratio in pure solution).