title: Determination of Sudan I in paprika powder by molecularly imprinted polymers-thin layer chromatography-surface enhanced Raman spectroscopic biosensor.
abstract: Sudan I is a carcinogenic and mutagenic azo-compound that has been utilized as a common adulterant in spice and spice blends to impart a desirable red color to foods. A novel biosensor combining molecularly imprinted polymers (MIPs), thin layer chromatography (TLC) and surface enhanced Raman spectroscopy (SERS) could determine Sudan I levels in paprika powder to 1 ppm (or 2 ng/spot). Sudan I spiked paprika extracts (spiking levels: 0, 1, 5, 10, 40, 70 and 100 ppm) were prepared. Sudan I imprinted polymers were synthesized by employing the interaction between Sudan I (template) and methacrylic acid (functional monomer), followed by washing to remove Sudan I leaving the Sudan I-binding sites exposed. MIPs were used as a stationary phase for TLC and could selectively retain Sudan I at the original spot with little interference. A gold colloid SERS substrate could enhance Raman intensity for Sudan I in this MIP-TLC system. Principal component analysis plot and partial least squares regression (R(2)=0.978) models were constructed and a linear regression model (R(2)=0.983) correlated spiking levels (5, 10, 40, 70 and 100 ppm) with the peak intensities (721 cm(-1)) of Sudan I SERS spectra. Both separation (30-40s) and detection (1s or 0.1s) were extremely fast by using both commercial bench-top and custom made portable Raman spectrometers. This biosensor can be applied as a rapid, low-cost and reliable tool for screening Sudan I adulteration in foods.
authors.affiliation: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4; Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Fang
authors.initials: F
authors.lastname: Gao
authors.affiliation: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
authors.forename: Yaxi
authors.initials: Y
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China.
authors.forename: Da
authors.initials: D
authors.lastname: Chen
authors.affiliation: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
authors.forename: Eunice C Y
authors.initials: ECY
authors.lastname: Li-Chan
authors.affiliation: Department of Chemistry, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Edward
authors.initials: E
authors.lastname: Grant
authors.affiliation: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4. Electronic address: xiaonan.lu@ubc.ca.
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Lu
mesh_terms: D015374:Biosensing Techniques; D002212:Capsicum; D002855:Chromatography, Thin Layer; D004396:Coloring Agents / Q000032:analysis* / Q000737:chemistry; D005506:Food Contamination / Q000032:analysis; D054802:Molecular Imprinting; D009284:Naphthols / Q000032:analysis* / Q000737:chemistry; D028321:Plant Preparations / Q000032:analysis*; D011108:Polymers / Q000737:chemistry; D011208:Powders; D013059:Spectrum Analysis, Raman; D017365:Spices / Q000032:analysis*
chemical_list: D004396:Coloring Agents; D009284:Naphthols; D028321:Plant Preparations; D011108:Polymers; D011208:Powders; C024336:1-phenylazo-2-naphthol
keywords: Food safety; Molecular imprinting; Multivariate analysis; Raman spectroscopy; Separation