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

Table 5

Results of stability in the autosampler of analytes (n = 3).

Analytes	Nominal concentration (ng/mL)	0 h			12 h			24 h
		Mean (%) ± SD	RSD (%)	RE (%)	Mean (%) ± SD	RSD (%)	RE (%)	Mean (%) ± SD	RSD (%)	RE (%)
Nirmatrelvir	5	5.1 ± 0.2	4.5	2.0	4.38 ± 0.21	4.8	−12.5	5.4 ± 0.3	4.9	7.2
	1000	1077 ± 32.4	3.0	7.7	908.4 ± 65.5	7.2	−9.2	982.2 ± 29.9	3.0	−1.8
	2000	2140 ± 78.1	3.7	7.0	2004 ± 15.6	0.8	0.2	2054 ± 71.3	3.5	2.7
Ritonavir	5	4.6 ± 0.2	3.6	−8.0	4.51 ± 0.16	3.4	−9.8	4.5 ± 0.2	3.7	−9.1
	1000	1110 ± 25.9	2.3	11.0	1079 ± 73.1	6.8	7.9	897.5 ± 65.2	7.3	10.3
	2000	2120 ± 33.1	1.6	6.0	1918 ± 12.2	0.6	4.1	1940 ± 46.8	2.4	−3.0