Subcategory: Physics (not Nanoscience)
Eshirdanya B. Mcghee - Alabama A&M University
Co-Author(s): Brianna Kenney, Carlton Farley, Kenneth Garcia, and Anup Sharma
Raman Spectroscopy has been successfully applied to detect various adulterants in food products at standoff distances ranging from one to ten meters with varying integration times. In this report, the results of detection of melamine in baby formula using conventional and standoff Raman spectroscopy are presented. For stand-off measurements, the Raman probe is connected to a 2 inch refracting telescope which allows for detection of Raman scatterings at distances ranging from 1-10 meters. The two most prominent Raman peaks for melamine are located at 670 and 980 cm-1, with the peak located at 670 cm-1 being more than twice as intense as the peak located at 980 cm-1 and are distinct from the Raman spectrum of baby formula, which is located at 1430 cm-1.
The concentrations of the melamine in powdered baby formula used in this study are in the range of 0.5-10% by weight. Using the conventional Raman measurements collected at ten seconds integration time, we observed that: (1) peak Raman intensities appear to increase uniformly as the concentration of melamine in the sample increases, (2) the lowest concentration of melamine that we were able to detect both the characteristic Raman peaks for melamine located at 670 cm-1 and 980 cm-1 is 3% by weight, and (3) for the 1% concentration of melamine, the only characteristic Raman peak detected was at 670 cm-1. A similar result is obtained for the measurements conducted at a standoff distance of 15 cm and 150 seconds integration time. In conclusion, the 785 nm Portable Raman system is found to be very useful in conventional and stand-off Raman detection and identification of various adulterants in food products. Adulteration of powdered baby formula with melamine was investigated, and it was found that stand-off Raman spectroscopy could be used for detection melamine in baby formula at concentrations as little as 0.5% by weight at distance of up to 15 cm using 2 inch refracting telescope coupled with 2 inch IR lens with focal length of 15 cm.
References: Okazaki, S., Hiramatsu, M., Gonmori, K., Suzuki, O., & Tu, A. (2009). Rapid nondestructive screening for melamine in dried milk by Raman spectroscopy. Forensic Toxicology, 27(2), 94-97.
Qin, J., Chao, K., & Kim, M. (2013). Simultaneous detection of multiple adulterants in dry milk using macro-scale Raman chemical imaging. Food Chemistry, 138(2-3), 998-1007.
Funder Acknowledgement(s): This work is supported by the U.S. Department of Homeland Security under the award numbers 2014-ST-062-000060 and 2010-ST-061-FD0001.
Faculty Advisor: Aschalew Kassu,