Table 3.
Analytical methods employed in the last ten years for the detection of antivirals currently tested for COVID-19 treatment, with their main advantages and drawbacks.
| Advantages | Drawbacks | ||
|---|---|---|---|
| Methods for direct detection and quantification | Potentiometry | Fast and economical possibility to monitor the drug of interest thanks to ion-selective electrodes, whose the electric potential created over membrane depends on its the activity and allows its quantification. | Still limited since many common ions occurring in biofluids and tissues could interfere with the measurement of the target analyte. |
| Spectrofluorimetry (FL) | Easy, less expensive and less time consuming methods; they offer better sensitivity compared to potentiometric methods. | Sometimes require derivatization steps before the detection to form fluorescent adducts, since not all the antivirals are characterized by native fluorescence. Endogenous compounds could interfere with the results of the analysis. | |
| Matrix Assisted Laser Desorption Ionization mass spectrometry (MALDI-MS) | Short analysis times and low ion suppression. | Quantification remains a major challenge due to problems associated with analyte recovery from the tissue and ionization matrix effects. | |
| Methods including a preliminary separation step | High performance liquid chromatography coupled to UV–Vis (HPLC-UV) | Better sensitivity compared to CE-UV. Possibility to carry out multiresidue analysis. | Sensitivity and selectivity are rather limited because LC-UV requires a huge volume of sample and complex sample preparation to detect drugs at a low concentration. |
| High performance liquid chromatography coupled to spectrofluorometric detection (LC-FL) | More sensitive and selective than LC-UV, since fluorescence is a characteristic of well-defined compounds. | Since not all the antivirals are characterized by native fluorescence, sometimes are required derivatization steps before the analysis. | |
| Capillary electrophoresis coupled to UV–Vis (CE-UV) | Faster analysis with higher efficiency than LC-UV, thanks to the drugs separation through a small capillary under the influence of an electric field. | Low concentration sensitivity | |
| High performance liquid chromatography coupled to mass spectrometry (LC-MS) | Higher selectivity and sensibility compared to LC-UV methods. Shorter analysis time. Possibility to carry out multiresidue analysis. | Susceptibility to matrix effects, due to the outcome of co-eluting interfering compounds on the analyte ionization. | |
| Ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS) | Improved chromatographic efficiency compared to high performance liquid chromatography (HPLC) columns. Less susceptible to matrix effect. | Due to the smaller particles in the column, a more tedious pre-treatment of the sample in order to avoid its clogging is needed. |