试纸法快速测定高粱中单宁的研究

Study on rapid detection of tannin content in sorghum by test paper method

探讨了试纸与单宁反应的最佳条件,提出了用Fe(SCN)3-壳聚糖试纸法快速检测高粱中单宁的方法。结果表明,在pH 7.0～9.0的条件下,单宁与试纸上的显色物质反应生成紫红色稳定络合物,试纸颜色深浅与样品中单宁浓度成正比,通过与标准色阶图谱比较确定单宁浓度。试纸最低检出限达1.0μg/mL,5 min即可实现检测。应用于7种高粱样品中单宁含量的测定,并通过与国标法测定结果比较,本方法可实现半定量检测,已应用于高粱样品中单宁的实时、快速检测。

In this work, many experiments were done to explore the optimum condition of the test paper reacting with tannins, and a new method to detect sorghum tannins by ferric thiocyanate-chitosan test paper was also proposed. The results showed that, a kind of magenta stable complex was generated after tannins reacted with the ferric thioeyanate test paper at pH 7.0 ～ 9.0. As the color of the test paper was proportional to the content of tannin in samples, it could be determined by comparing with the standard colorimetric card. With this method, the detection limit of tannin was 1.0 x 10-3 mg/mL, and specially, the detection time could be within 5 mins. By comparing with GBT 15686 -2008, this method was simple, convenient, and could realize semi quantitative detection when appled to detection of tannin in 7 kinds of sorghum samples. Above all, the test paper method was simple, convenient, stable, and could realize real-time and fast detection of the tannin content in sorghum samples.