Table 2.
Linearities, regression equation, correlation coefficients, limit of detection (LOD), and limit of quantitation (LOQ) for glycryrrhizic acid (GA), liquiritin (LQ) and liquiritigenin (LG)
| Compounds | Linear range (ng/ml) | Regression equationa | Correlation coefficient | LODb (ng/ml) | LOQc (ng/ml) |
|---|---|---|---|---|---|
| Glycyrrhizic acid (GA) | 12.5–5000 | Y = 0.0004x – 0.0055 | 0.9999 | 4.62 | 13.99 |
| Liquiritin (LQ) | 12.5–1000 | Y = 0.0059x + 0.0451 | 0.9997 | 1.27 | 3.86 |
| Liquiritigenin (LG) | 12.5–500 | Y = 0.0289x + 0.1574 | 0.9998 | 0.54 | 1.64 |
ay: Analyte area / IS area; x: concentration (ng/mL) of compounds
bLOD = 3.3 x δ /S (δ; standard deviation, S; slope of the calibration curve)
cLOQ = 10 x δ /S (δ; standard deviation, S; slope of the calibration curve)