基于红色碳量子点的荧光法快速检测饮料中的胭脂红

Rapid Detection of Carmine in Beverages Using a Fluorescence Method Based on Red Carbon Quantum Dots

该研究以红色碳量子点为荧光探针,建立了一种饮料中胭脂红的荧光快速检测方法,以满足食品着色剂胭脂红的检测需求。首先以对苯二胺为碳源,于180℃水热反应合成红色碳量子点(RCDs)。研究发现所制备的RCDs的荧光发射峰与胭脂红的紫外可见吸收峰明显重叠,且两者之间存在内滤效应。基于内滤效应机理,建立了一种对胭脂红定量检测的荧光快速检测方法。结果表明:在0.5~50μg·mL^(-1)范围内胭脂红的浓度与RCDs的荧光强度比值呈线性相关,线性方程为I F0/I F=0.059 c+0.979,相关系数(r 2)为0.978,检出限为0.397μg·mL^(-1),3个加标水平下的回收率为93.1%~101%,相对标准偏差(RSD)为0.97%~2.1%。该方法具有快速、灵敏度高及稳定性好的特点,可用于实际饮料样品中胭脂红的检测。

Carmine as a kind of food colorants is commonly used in food industry.However,irrational and inappropriate use of carmine will seriously threaten human health.At present,the detection of carmine mainly relies on the traditional methods such as high-performance liquid chromatography(HPLC),high performance capillary electrophoresis,etc.,which always involve expensive instruments,professional personnel and complicated pretreatment procedures.Thus,it s indispensable to develop rapid,sensitive and visual detection methods for carmine.To meet this demand,a fluorescence method was established for the rapid detection of carmine in beverages specifically.Firstly,red carbon quantum dots(RCDs)were synthesized via hydrothermal treatment at 180℃by using p-phenylenediamine as the carbon source.The morphology and particle size distribution of the prepared RCDs were observed by transmission electron microscopy(TEM).Furthermore,Fourier transform infrared spectroscopy(FTIR)was used to characterize the functional groups on the surface of RCDs,while the element composition of RCDs and their chemical states of elements were determined by X-ray photoelectron spectroscopy(XPS).To state the fluorescence quenching mechanism clearly,the fluorescence lifetime,the UV-Vis absorption spectra and fluorescence spectra were investigated.It was found that the absorption peak of carmine overlaps with the fluorescence emission spectrum of the prepared RCDs.Thus,a possible mechanism for fluorescence quenching was proposed as inner filter effect mechanism.Based on this mechanism,a fluorescence sensor for sensitive determination of carmine was designed,of which the detection performance depended on the detection conditions.To obtain the optimal analytical performance,the experimental parameters,including the excitation wavelength and pH values,were optimized.Under the optimized experimental conditions,the proposed sensor exhibited a linear response to carmine in the concentration range of 0.5-50μg·mL^(-1),with a linear equation of I F0/I F=0.059 c+0.979,a correlation coefficient(r 2)of 0.978 and a detection limit of 0.397μg·mL^(-1).The practical application of the proposed sensor was verified by HPLC with spiked beverage samples.The recoveries at three spiked levels ranged from 93.1%to 101%,with relative standard deviations(RSDs)of 0.97%-2.1%.Moreover,the color variation could be directly observed under the illumination of a 365 nm UV lamp with the naked eye,which could be used in the semiquantitative analysis for carmine content.With the advantages of rapidness,high sensitivity and stability,this method could be used for the detection of carmine in actual beverage samples.The research on this fluorescent method is of great theoretical value to develop new methods for carmine detection.In addition,the established method has a practical application value for on-site safety regulation on the illegal use of carmine.