Table 2. Proton spin-lattice relaxation time (T 1) values for 13 selected metabolites and the method validation parameters for 1HNMR method.
| Metabolites | δ(ppm) | T 1 (s) (n = 3) | Regression equation (n = 3) | r 2 | Intra-day precision (n = 6) RSD (%) | Inter-day precision (n = 3) RSD (%) | Repeatability (n = 6) RSD (%) | Stability (n = 6) RSD (%) | Average recoverya (%) ± SD (n = 3) |
| Valine | 1.03 (3H) | 0.944±0.049 | y = 7.9917x - 0.1254 | 0.9996 | 0.79 | 0.84 | 1.83 | 1.67 | - |
| Threonine | 1.31 (3H) | 1.323±0.102 | y = 7.9895x - 0.1288 | 0.9995 | 0.49 | 0.98 | 1.94 | 0.99 | - |
| Alanine | 1.47 (3H) | 1.451±0.120 | y = 11.536x - 0.0821 | 0.9997 | 0.61 | 0.35 | 1.46 | 0.58 | 106.6±1.2 |
| Pyroglutamate | 2.41 (2H) | 2.249±0.044 | y = 3.9348x - 0.0387 | 0.9980 | 0.20 | 0.29 | 1.48 | 0.37 | - |
| Succinate | 2.42 (4H) | 1.844±0.268 | y = 9.7223x - 0.2087 | 0.9993 | 0.89 | 0.93 | 1.85 | 2.21 | - |
| Asparagine | 2.76 (1H) | 0.562±0.019 | y = 1.8370x - 0.1871 | 0.9979 | 0.60 | 1.49 | 2.75 | 1.78 | - |
| Malonate | 3.19 (2H) | 2.116±0.136 | y = 0.7533x - 0.0317 | 0.9972 | 0.20 | 0.56 | 1.66 | 1.43 | - |
| Fructose | 4.10 (3H) | 3.303±0.210 | y = 1.2045x - 0.2608 | 0.9998 | 0.45 | 0.34 | 1.69 | 2.06 | - |
| Glucose | 5.24 (1H) | 1.684±0.206 | y = 0.5486x - 0.0912 | 0.9997 | 0.32 | 0.68 | 2.59 | 1.32 | 106.6±2.5 |
| Rutinose | 5.44 (1H) | 1.447±0.164 | y = 2.4419x - 0.1850 | 0.9992 | 0.59 | 0.76 | 2.49 | 1.78 | - |
| Salvianic acid | 6.74 (1H) | 1.843±0.139 | y = 1.2845x - 0.1858 | 0.9994 | 0.23 | 0.34 | 2.01 | 1.23 | 98.3±2.1 |
| Procatechuic acid | 7.41 (1H) | 3.542±0.326 | y = 0.5172x - 0.0083 | 0.9983 | 0.67 | 0.93 | 1.93 | 1.99 | - |
| Procatechuic aldehyde | 9.63 (1H) | 2.932±0.436 | y = 1.2468x - 0.0013 | 0.9992 | 0.78 | 0.85 | 1.72 | 1.82 | 91.3±4.0 |
a
Recovery (%) = [(found−original)/spiked]×100.