方法可能不对。
Absorbance (2.2.25). Purge with nitrogen R for 15 min. The
absorbance, measured using water R as the compensation
liquid, is not more than 0.30 at 275 nm and not more than 0.20
at both 285 nm and 295 nm. Examined between 270 nm and
350 nm, the substance to be examined shows no absorption
maximum.