Qualitative and Compliance Analysis of Impurities in the Ethanol Recovered from Ethanol Deposition Solution of Aqueous Extract of Lonicerae Japonicae Flos

OBJECTIVE To explore the influence of reusing and recycling times on the quality of ethanol recovered from ethanol deposition solution of aqueous extract of Lonicerae Japonicae Flos. METHODS The ethanol in five consecutive batches of Lonicerae Japonicae Flos water extract ethanol deposition was recovered by vacuum distillation. The impurities in five batches of recovered ethanol and the recovered ethanol when partial coking caused by temperature runaway were qualitatively analyzed by headspace solid phase micro extraction combined with gas chromatography-mass spectrometry(HS-SPME/GC-MS), and the ultraviolet absorbance of each batch of recovered ethanol was also analyzed. RESULTS Styrene was the only impurity in the first and second batch of recovered ethanol; there were five impurities in the third and fourth batch of recovered ethanol; the number of impurities in the fifth batch of recovered ethanol increases to 17. When partial coking was occurred, the exogenous impurities in the recovered ethanol increased dramatically to forty-one, and there were harmful substances such as ninhydrin and naphthalene. The ultraviolet absorbance of the third to fifth batch of recovered ethanol exceed the upper limit stipulated in the second part of Chinese Pharmacopoeia, 2020 Edition. While the ultraviolet absorbance of the recovered ethanol when partial coking takes place exceeds the standard of the pharmacopoeia greatly. CONCLUSION The recovered ethanol should be treated after being reused two times, so that its ultraviolet absorbance level and impurity type are equivalent to that of fresh ethanol before it can be used again. The method provides reference for the quality control and compliance use of recovered ethanol.