A Simple and Rapid LC-MS/MS Method for the Quantification of Nirmatrelvir/Ritonavir in Plasma of Patients with COVID-19

Table 3

Inter- and intraday precision and accuracy of analytes (n = 5).

Analytes	Nominal concentration (ng/mL)	Interday measured concentration (ng/mL) ± SD	RSD (%)	RE (%)	Intraday measured concentration (ng/mL) ± SD	RSD (%)	RE (%)
Nirmatrelvir	5	4.8 ± 0.4	7.9	−3.9	5.0 ± 2.2	9.9	0.1
	1000	983.3 ± 89.1	9.1	−1.7	982.3 ± 78.0	7.9	−1.8
	2000	2050 ± 105.6	5.2	2.5	2088 ± 104.4	5.0	4.4
Ritonavir	5	4.8 ± 0.7	13.6	4.1	5.1 ± 0.7	13.4	1.5
	1000	1031 ± 118.7	11.5	3.1	1078 ± 18.1	1.7	7.8
	2000	2088 ± 100.4	4.8	4.4	1998 ± 16.2	0.8	−0.1