Table 2.
Regression equation, correlation coefficients, linearity ranges, and limits of detection (LOD) and quantitation (LOQ) of the 12 investigated compounds.
| No. | Compound | Calibration Curves | r2 | Linear Range (μg/mL) | LOD (ng/mL) | LOQ (ng/mL) |
|---|---|---|---|---|---|---|
| 1 | Fumaric acid | y = 254.90x – 708.31 | 0.9996 | 0.709–709.000 | 9.13 | 18.89 |
| 2 | Caffeic acid | y = 1149.30x + 1096.9 | 0.9994 | 0.011–22.250 | 1.29 | 2.15 |
| 3 | Catalpol | y = 27.61x – 84.26 | 0.9998 | 0.088–175.500 | 3.10 | 8.69 |
| 4 | Aucubin | y = 128.38x + 131.04 | 0.9994 | 0.457–914.000 | 5.62 | 12.33 |
| 5 | p-Coumaric acid | y = 3854.90x – 2322.20 | 0.9998 | 0.026–53.000 | 1.88 | 2.07 |
| 6 | Ferulic acid | y = 950.10x – 1032.90 | 0.9988 | 0.064–128.000 | 3.47 | 9.56 |
| 7 | Harpagide | y = 81.58x + 275.52 | 0.9996 | 0.284–569.000 | 3.94 | 10.75 |
| 8 | Cinnamic acid | y = 1809.60x + 3360.20 | 0.9988 | 0.063–126.800 | 4.11 | 8.42 |
| 9 | p-Methoxycinnamic acid | y = 1776.50x + 5756.80 | 0.9996 | 0.213–426.000 | 4.21 | 9.68 |
| 10 | Verbascoside | y = 203.29x +1645.80 | 0.9996 | 0.872–1744.000 | 9.45 | 19.65 |
| 11 | Angoroside C | y = 178.95x +1045.10 | 0.9990 | 0.253–470.000 | 3.85 | 8.71 |
| 12 | Harpagoside | y = 115.78x + 596.85 | 0.9996 | 0.099–198.000 | 3.47 | 7.25 |