Table 2.
A description of the different identification methods for CEP.
| Methods | Operating conditions | Results | Reference |
|---|---|---|---|
| HPLC | Angela C18 column (250 mm × 4.6 mm, 5 µm); The mobile phase (v/v): acetonitrile–water (52:48,0.5 % triethylamine and 0.01 % phosphoric acid); The column temperature (℃):30; The injection volume (µL): 20 | A good linearity (μg/mL): 9–216 (r = 0.9997), RSD value at 2.0 % | 71 |
| HPLC | Symmetry C8 column (250 mm × 4.6 mm, 5 µm); The mobile phase (v/v): 25 mM potassium phosphate buffer (pH 3.5, adjusted with orthophosphoric acid) - acetonitrile (8:2); The mobile phase flow rate (mL/min): 1.0; The injection volume (µL): 20; The column temperature (℃): 25; The UV spectra detection wavelength(nm): 282 | A good linear behavior was observed with values of r2 > 0.9964 | 37 |
| RP-HPLC | AlltechRP C18 column (250 mm × 4.6 mm, 5 µm); The mobile phase (v/v): methanol-0.05 % triethanolamine buffered (75:25); The mobile phase flow rate (mL/min): 0.8; The injection volume (µL): 10; The column temperature (℃): 30; The UV spectra detection wavelength (nm): 283 | A good linearity (μg/mL): 0.10032–1.0032 (r = 0.9999), RSD value at 1.84 % | 74 |
| RP-HPLC | Hypersil C18 column (250 mm × 4.6 mm, 5 µm); The mobile phase (v/v/v): methanol–water- triethanolamine (75:23:0.20); The mobile phase flow rate (mL/min): 1.0; The injection volume (µL):20; The column temperature (℃): 30; The UV spectra detection wavelength (nm): 282 | A good linearity (μg/mL): 0.12–0.13 (r = 0.994) | 72 |
| MSPD-HPLC | Phenomenex Gemini C18 column (250 mm × 4.6 mm, 5 µm); The mobile phase (v/v): acetonitrile-triethanolamine (70:30); The mobile phase flow rate (mL/min): 1.0; The injection volume (µL):20; The column temperature (℃): 40; The UV spectra detection wavelength (nm): 282 | A good linearity (μg/mL): 14.88–238 (r = 0.9994) | 75 |
| UPLC-QTOF-MS | UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 µm); The mobile phase (v/v): acetonitrile and aqueous formic acid (0.1 %); The mobile phase flow rate (mL/min): 0.4; The injection volume (µL): 5; The column temperature (℃): 40;MS: Scan monitoring (m/z): 100–1200; Capillary voltage (kV): 0.5; Sample cone voltage (V): 40; Extraction cone voltage (V): 4; Source temperature (℃): 100; Desolvation temperature (℃): 300; Desolvation gas flow (L/h): 800; |
MS/ MS Fragmentation: 564.2397[M + H –NH2CH3]+ Molecular Formula: C37H38N2O6 |
70 |
| UV–vis | Solvent: anhydrous ethanol solution; Solid-liquid ratio (µg /ml): 40:1; The UV spectra detection wavelength (nm): 282; | A good linearity (μg/mL): 10–70 (r = 0.9995) | 73 |
Abbreviations: RSD: relative standard deviation; HPLC: high performance liquid chromatography; RP-HPLC: reversed phase high performance liquid chromatography; MSPD: matrix solid-phase dispersion; UPLC: ultra-high performance liquid chromatography; QTOF: quadrupole time-of fligh; MS: mass spectrometry; UV–vis: ultraviolet-visable.