Table 2.
Regression data, limit of detection (LOD), and limit of quantification (LOQ) for the five external standards.
| Standard | Calibration curve | r 2 | LOD | LOQ | Recovery (%) ± RSD | |
|---|---|---|---|---|---|---|
| (mg/L) | (mg/L) | 50 mg/L | 100 mg/L | |||
| Gallic acid | y = 25.171x + 335.04 | 0.9993 | 0.032 | 0.107 | 79.6 ± 6.1 | 85.2 ± 0.5 |
| Protocatechuic acid | y = 37.614x + 1137.3 | 0.9982 | 0.030 | 0.102 | 88.5 ± 0.2 | 87.8 ± 0.5 |
| 7-Hydroxycoumarin | y = 10.873x − 28.39 | 0.9955 | 0.142 | 0.473 | 102.8 ± 0.7 | 98.6 ± 11.6 |
| Quercetin 3-O-glucoside | y = 30.166x + 267.56 | 0.9949 | 0.037 | 0.125 | 76.1 ± 0.1 | 90.9 ± 14.0 |
| Kaempferol | y = 39.493x + 1475.4 | 0.9907 | 0.028 | 0.094 | 100.0 ± 3.0 | 97.4 ± 1.4 |
y: peak area of standard; x: concentration of standard (mg/L).