| Age group(y) | Cut-off value(μmol/L) | Specificity | Sensitivity | AUC | P |
| 18-34 | 0.09 | 12.00 | 96.25 | 0.510 | 0.850 |
| 35-49 | 0.10 | 38.89 | 94.00 | 0.686 | 0.002 |
| ≥50 | 0.11 | 63.64 | 98.00 | 0.890 | < 0.001 |
Fig 2 Effect of different mobile phase ratios on GABA response Chromatograms obtained with different mobile phase compositions. A: Mobile phase A1 (0.05% formic acid in water) and mobile phase B1 (90% acetonitrile in water) containing 5 mmol/L ammonium acetate; B: Mobile phase A1 (0.05% formic acid in water) and mobile phase B1 (90% acetonitrile in water) containing 0.10% formic acid and 5 mmol/L ammonium acetate; C: Mobile phase A1 (0.05% formic acid in water) and mobile phase B1 (90% acetonitrile in water) containing 0.175% formic acid and 5 mmol/L ammonium acetate.