紫外分光度法在5-羟甲基糠醛含量测定中影响因素的研究

Study on influencing factors of determination of 5-hydroxymethylfurfural by UV spectrophotometry

紫外光谱在测定5-羟甲基糠醛含量时存在一定的误差,笔者对催化反应的溶剂、催化剂和原料等因素的影响进行了探索。实验结果表明,5-HMF标样在284 nm波长下具有非常好的线性关系;反应溶剂离子液体[EMIM]Cl和[BMIM]Cl与二甲基亚枫(DSMO)在特征吸收峰附近几乎没有吸收,而正丁醇有微量吸收;反应催化剂CrCl3、AlCl3、ZnCl2几乎没有吸收,FeCl3、硅钨酸、铬酸钾和磷钼酸有一定吸收(FeCl3>硅钨酸>铬酸钾>磷钼酸);反应原料果糖和葡萄糖在特征吸收峰几乎没有吸收;二甲基亚枫(DSMO)和CrCl3的混合液体对紫外光谱的吸收存在叠加效应。因此,紫外光谱测定5-HMF含量存在一定的误差根本原因是由于分析检测液中其他物质在其特征吸收峰附近有一定的吸收所致。可以采用复配参比液和降低其他物质的浓度等措施降低干扰,提高测量的准确度。

There is a certain degree of error when 5-hydroxymethylfurfural is measured with UV spectrophotometry. The influences of the solvent of the catalytic reaction ,the catalyst and raw materials are studied. The results show that the standard sample of 5-HMF has a very good linear relationship at 284 nm wavelength. Except n-butanol, the reaction solvents such as [ BMIM ] Cl, [ BMIM ] Cl and dimethyl sulfoxide （DSMO） have no absorb around the characteristic absorption peak. The reaction catalysts like CrCl3 , A1Cl3 and ZnCl2, have no absorption, but FeC;3 , silicotungstic acid, potassium chromate and phospho-molybdic acid have some absorption. The raw materials such as fructose and glucose, have no absorption to UV light as well. The mixture of dimethyl sulfoxide and CrCl3 has duplicate effect on absorption to UV light. Therefore,basic reason for error of determining 5-HMF using UV spectroscopy is that other substances in the test solution have certain absorption to UV light near the characteristic absorption peak. Using a mixed reference solution and reducing the concentration of the other substances can reduce the degree of interference and improve the accuracy of measurement.