Table 1.
Retention time, wavelength (λ), regression equation, limit of detection (LOD), and limit of quantification (LOQ) during HPLC-UV of flavonoid standards.
| No. | Compound | Retention Time (min) | λ 1 (nm) | Regression Equation 2 | LOD 3 (μg/mL) | LOQ 3 (μg/mL) | Abbre- Viation |
|---|---|---|---|---|---|---|---|
| 1 | Procyanidin B1 | 9.7 | 280 | y = 11.12x − 1.71 | 0.84 | 2.56 | Pr B1 |
| 2 | (+)-Catechin | 10.1 | 280 | y = 14.10x − 1.72 | 0.67 | 2.02 | (+)-Ca |
| 3 | Delphinidin-3,5-diglucoside | 11.6 | 520 | y = 22.35x − 6.10 | 0.99 | 2.99 | Del-di |
| 4 | Procyanidin B2 | 13.3 | 280 | y = 37.48x − 6.02 | 0.80 | 2.41 | Pr B2 |
| 5 | (-)-Epicatechin | 15.1 | 280 | y = 11.64x − 2.06 | 0.85 | 2.58 | (−)-Epi |
| 6 | Delphinidin-3-O-glucoside | 16.7 | 520 | y = 59.52x − 38.58 | 1.99 | 6.04 | Del-glu |
| 7 | Cyanidin-3-O-galactoside | 17.4 | 520 | y = 64.97x − 12.84 | 0.96 | 2.91 | Cy-gal |
| 8 | Cyanidin-3-O-glucoside | 19.1 | 520 | y = 57.62x − 12.71 | 1.09 | 3.30 | Cy-glu |
| 9 | Cyanidin-3-O-arabinoside | 20.5 | 520 | y = 51.51x − 11.54 | 1.11 | 3.36 | Cy-ara |
| 10 | Pelargonidin-3-O-glucoside | 21.3 | 520 | y = 31.84x − 6.29 | 0.98 | 2.96 | Pel-glu |
| 11 | Petunidin-3-O-glucoside | 21.8 | 520 | y = 56.17x − 29.61 | 1.86 | 5.64 | Pet-glu |
| 12 | Luteolin-8-C-glucoside | 24.9 | 360 | y = 53.77x − 4.83 | 0.49 | 1.49 | Lut-glu |
| 13 | Malvidin-3-O-glucoside | 26.3 | 520 | y = 48.43x − 21.34 | 1.67 | 5.06 | Mal-glu |
| 14 | Procyanidin A2 | 27.0 | 280 | y = 10.64x − 1.78 | 0.92 | 2.80 | Pr A2 |
| 15 | Myricetin-3-O-rhamnoside | 28.8 | 360 | y = 64.46x − 10.05 | 0.77 | 2.34 | My-rha |
| 16 | Quercetin-3-O-galactoside | 30.1 | 360 | y = 30.22x − 4.20 | 0.66 | 2.01 | Qu-gal |
| 17 | Quercetin-3-O-rutinoside | 30.8 | 360 | y = 28.29x − 3.76 | 0.63 | 1.90 | Qu-rut |
| 18 | Quercetin-3-O-rhamnoside | 35.6 | 360 | y = 39.95x − 6.95 | 0.89 | 2.69 | Qu-rha |
| 19 | Kaempferol-3-O-glucoside 4 | 35.6 | 360 | y = 41.27x − 19.89 | 2.16 | 6.54 | Kae-glu |
1 Detection wavelength for each compound according to Vagiri et al. [27]. 2 Linear range for all compounds was tested 2–100 μg/mL, resulting in R2 > 0.999. HPLC conditions as described in the section “Quantification”. 3 Calculated as: LOD = (3.3 × SD)/b; LOQ = (10 × SD)/b, where SD is residual standard deviation of the linear regression and b is slope of the regression line [29]. 4 Kaempferol-3-O-glucoside co-eluted with quercetin-3-O-rhamnoside, so its calibration curve was built separately.