Sensitive determination of Sudan dyes in foodstuffs by Mn–ZnS quantum dots

• It was the first time to apply Mn–ZnS QDs luminescence sensing system to detect Sudan dyes.
• No complex process and expensive instruments except fluorescence spectrophotometer were needed.
• The detect method was novel, simple and convenient.
• The method showed high selectivity toward Sudan dyes detection.

A novel luminescence sensing system has been designed for Sudan dyes detection based on the quenched fluorescence (FL) of oleic acid-functionalized Mn–ZnS quantum dots (QDs). The Sudan dyes could quench the fluorescence signal of Mn–ZnS QDs due to the so-called inner filter effect. Herein, it was demonstrated that this facile methodology could offer a rapid, reliable and selective detection of Sudan dyes, and the detection limits of Sudan I, II, III, and IV were 24.6, 32.7, 2.1, and 3.2 ng/mL, respectively. In this work, Sudan dyes were mainly detected in hot chili sauce, sausage, egg and tomato sauce, and Sudan I was chosen as spiked substance owning to its wide use as a coloring matter among Sudan dyes in many industrial and daily products. Furthermore, the recoveries of Sudan I from the standard fortified blank samples were in a range of 93.0–107.0%, and the relative standard deviations (RSDs) were lower than 2.8% (n = 3).

Initially, the free Mn–ZnS QDs capped with oleic acid showed strong FL in solution. However, the FL of Mn–ZnS QDs was quenched significantly in the presence of Sudan dyes through the inner filter effect.Figure optionsDownload as PowerPoint slide