Research Article
A Simple and Rapid LC-MS/MS Method for the Quantification of Nirmatrelvir/Ritonavir in Plasma of Patients with COVID-19
Table 6
Results of benchtop stability, three frozen-thaw cycles stability, and long-term stability of analytes (n = 3).
| Analytes | Nominal concentration (ng/mL) | Room temperature 4 h | Three frozen-thaw cycles | Long-term stability | Mean (%) ± SD | RSD (%) | RE (%) | Mean (%) ± SD | RSD (%) | RE (%) | Mean (%) ± SD | RSD (%) | RE (%) |
| Nirmatrelvir | 5 | 4.6 ± 0.3 | 6.9 | −7.5 | 4.9 ± 0.6 | 11.2 | −1.2 | 5.4 ± 0.3 | 4.8 | 7.2 | 1000 | 908.4 ± 65.5 | 7.2 | −9.2 | 983.1 ± 67.3 | 6.8 | −1.7 | 973.4 ± 26.2 | 2.7 | −2.7 | 2000 | 1851 ± 26.0 | 1.4 | −7.5 | 2053 ± 110.3 | 5.4 | 2.7 | 2055 ± 31.9 | 1.6 | 2.8 |
| Ritonavir | 5 | 4.5 ± 0.2 | 3.4 | −9.8 | 4.8 ± 0.6 | 12.4 | −5.0 | 4.5 ± 0.2 | 3.7 | −9.1 | 1000 | 1076 ± 32.0 | 3.0 | 7.6 | 1076 ± 76.6 | 7.1 | 7.6 | 951.7 ± 53.8 | 5.7 | −4.8 | 2000 | 1873 ± 95.5 | 5.1 | −6.4 | 2101 ± 106.2 | 5.1 | 5.0 | 1806 ± 39.1 | 3.8 | −9.7 |
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