PROCEDURE
Inject about 20 µL of the
Test solution into a liquid chromatograph (see
Chromatography 621), equipped with a 280-nm detector and a 4.6-mm × 15-cm column that contains packing L1. The flow rate is about 2.0 mL per minute. The area of the C
9H
12N
2O
6 peak is not less than 99% of the total peak area.