Extraction of brown pigment from the shell of Suzhou gorgon euryale seed and it's FT-IR spectroscopy analysis

Brown pigment was extracted from the shell of Suzhou gorgon euryale seed by using the method of solvent extraction.The influences of different factors such as the different solvents, the ratio of material to liquid, temperature and time on the extraction effect of brown pigment were compared. The suitable conditions of extracting brown pigment from the shell of Suzhou gorgon euryale seed were determined through the orthogonal experiment.The purified brown pigment were obtained separately with the method of ethanol- precipitation and hydrochloric acid-precipitation and its structure was analyzed by using a fourier transform infrared spectroscopy ( FT-IR) .The results showed that the suitable conditions of extracting brown pigment were as follows: 2% NaOH solution as extraction agent, material- liquid ratio 1 ∶ 30, extraction temperature 60℃, extraction time 3h. IR spectrogram of pigment Ⅰ and pigment Ⅱ obtained with the method of ethanol- precipitation and acid-precipitation revealed that 3390.30, 1633.44, 1456.02, 1338.38cm- 1were both the main absorption, but significant difference at 2925.53, 2854.18, 1716.36, 1234.24, 867.82, 815.75, 777.18cm- 1, etc.These indicated that brown pigmentⅠand Ⅱ both had functional groups including phenolic hydroxyl groups and aromatic rings structure. Brown pigmentⅠincluded the ester carbonyl structure and C- N structure, but brown pigment II didn't exist in these structures and had substituents in the aromatic ring which brown pigmentⅠdidn't contain.