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

Table 4

Recovery and matrix effect of analytes.

Analytes	Nominal concentration (ng/mL)	Recovery		Matrix effect
		Mean (%) ± SD	RSD (%)	Mean (%) ± SD	RSD (%)
Nirmatrelvir	5	98.7 ± 6.5	6.6	87.1 ± 3.7	4.2
	1000	92.0 ± 4.4	4.8	97.8 ± 1.6	1.6
	2000	106.7 ± 2.0	1.9	87.8 ± 3.5	3.9
Ritonavir	5	105.8 ± 8.0	7.5	91.7 ± 9.1	9.9
	1000	89.3 ± 7.7	8.6	87.8 ± 5.8	6.6
	2000	85.7 ± 7.0	8.1	111.8 ± 7.3	6.5