电喷雾解析电离质谱法对食品中苏丹红染料的快速检测

Desorption Electrospray Ionization Mass Spectrometry for Fast Detection of Sudan Dyes in Foods Without Sample Pretreatment

将电喷雾解析电离质谱法应用于偶氮类染料的表面解析电离质谱法研究,在优化实验条件后,应用甲醇-水-醋酸(49∶49∶2,V/V)混合溶液作为喷雾溶剂,在不需要样品预处理的情况下,成功地测定了辣椒面、番茄酱、火腿肠、鸡蛋饼中微量的苏丹红类染料,并且应用串联质谱法对测定结果进行了鉴定,排除了测定结果的假阳性。在辣椒面、番茄酱、火腿肠、鸡蛋饼中苏丹红1号的检出限分别0.01 pg/mm2、0.02 pg/mm2、0.02 pg/mm2和1.0 pg/mm2。单个样品的测定时间约1 m in,如果配合小型质谱仪,则可能对食品中的苏丹红类染料进行现场快速测定。

Desorption electrospray ionization mass spectrometry （DESI-MS） was employed for fast direct detection of Sudan dyes such as Sudan Ⅰ , Sudan Ⅱ , Sudan Ⅲ and Sudan Ⅳ presented in various foods, including chili powder, tomato sauce, sausage and fried egg. The operation parameters for both DESI and LTQ were optimized so that reliable signal of analyte was generated using a mixture of methanoL/water/acetic acid （49：49：2） as electrospray liquid. All the analytes gave predominant signal at m/z 249, 277, 353, 381, which was corresponding to the protonated molecules of Sudan Ⅰ , Sudan Ⅱ, Sudan Ⅲ and Sudan Ⅳ, respectively. The structures of the protonated molecules were confirmed with high confidence by tandem DESI- MS/MS, which yielded characteristic fragments （e. g. m/z 156） for the four dyes, leading into elimination of false positive alert, which is usually common in results of direct fast detection of trace analyte in such a complicated matrix as tomato sauce, fried egg, etc. Detection limits of Sudan dyes in chili powder, sauce tomato, sausage, fried egg were found to be less than 0.01 pg/mm^2,0.02 pg/mm^2,0.02 pg/mm^2, 1.0 pg/mm^2, respectively. The mean analysis time for a single sample was about 1 minute. It was also proposed to couple DESI source for miniature mass spectrometer for fast in-situ analysis of complicated samples without pretreatment.