CTAB-assisted AgBr -bismuth oxybromide based novel SERS substrate for label-free, non-invasive quantitative detection of detrimental synthetic food colorants

Synthetic food colorants like Rhodamin 6G, Allura red, Amaranth, Tartrazine, and Sunset yellow although banned by several governments continues to be used in food products. A method for detection in a non-invasive label free manner is reported in two parts. Herein, a novel CTAB assisted-BiOBr (BOB), Ag0.09 BOB and Ag0.15 BOB (CTAB-AgBr-Bi3O4Br/BiOBr) substrate was prepared by chemical precipitation method and their SERS (surface enhanced Raman spectroscopy) activity was assessed by detecting the aforementioned synthetic food colorants in a non-invasive label free manner. Excellent SERS activity was observed for all these dyes. Ag0.15 BOB substrate showed higher SERS activity than others. The lowest detection limit was determined to be 10 μM for Rhodamin 6G, 50 μM for Allura red, Amaranth and 40 μM for Tartrazine and Sunset yellow. Binary mixture analysis was also performed to analyse the closely related food colorants paving way for their quantitative detection in real food products.