如何快速检测天然色素中是否掺杂合成色素或者工业染料是食品分析检测中的一个难题。 天然辣椒红色素因兼具着色和药理功效而被广泛用于食品中， 但又因其稳定性较差而被不法商贩掺杂苏丹红来获利。 本文利用红外光谱技术的宏观指纹特性， 对掺杂于天然辣椒红色素中苏丹红的1 621， 1 500和751 cm-1处的强峰， 再通过二阶导数图谱分析将谱图信息放大， 辅以指纹区684和496 cm-1处的谱峰的佐证， 可以快速识别辣椒红中是否添加有苏丹红， 检测限量可以达到1％。

How to rapidly determine synthesized pigments or dyes adulterated in natural pigments is a difficult problem for food analysts. Natural paprika red is widely used in foods because of its coloration and pharmaceutical effect, but it is sometimes adulterated with Sudan dyes for its poor stability under light or heat treatment. In the present paper, the macro-fingerprint characteristic of infrared spectroscopy was utilized to identify Sudan dyes adulterated in paprika red. The strong peaks at 1 621, 1 500 and 751 cm-1 in FTIR spectra and at the fingerprint region of 753, 684 and 496 cm-1 in the secondary deriative FTIR spectra were remarkable characteristics for Sudan dyes adulterated in paprika red, of which the limit of determination was about 1%.