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Proceedings Paper

Rapid, sensitive and reproducible method for point-of-collection screening of liquid milk for adulterants using a portable Raman spectrometer with novel optimized sample well
Author(s): Michel K. Nieuwoudt; Steve E. Holroyd; Cushla M. McGoverin; M. Cather Simpson; David E. Williams
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Paper Abstract

Point-of-care diagnostics are of interest in the medical, security and food industry, the latter particularly for screening food adulterated for economic gain. Milk adulteration continues to be a major problem worldwide and different methods to detect fraudulent additives have been investigated for over a century. Laboratory based methods are limited in their application to point-of-collection diagnosis and also require expensive instrumentation, chemicals and skilled technicians. This has encouraged exploration of spectroscopic methods as more rapid and inexpensive alternatives. Raman spectroscopy has excellent potential for screening of milk because of the rich complexity inherent in its signals. The rapid advances in photonic technologies and fabrication methods are enabling increasingly sensitive portable mini-Raman systems to be placed on the market that are both affordable and feasible for both point-of-care and point-of-collection applications. We have developed a powerful spectroscopic method for rapidly screening liquid milk for sucrose and four nitrogen-rich adulterants (dicyandiamide (DCD), ammonium sulphate, melamine, urea), using a combined system: a small, portable Raman spectrometer with focusing fibre optic probe and optimized reflective focusing wells, simply fabricated in aluminium. The reliable sample presentation of this system enabled high reproducibility of 8% RSD (residual standard deviation) within four minutes. Limit of detection intervals for PLS calibrations ranged between 140 - 520 ppm for the four N-rich compounds and between 0.7 - 3.6 % for sucrose. The portability of the system and reliability and reproducibility of this technique opens opportunities for general, reagentless adulteration screening of biological fluids as well as milk, at point-of-collection.

Paper Details

Date Published: 17 February 2017
PDF: 12 pages
Proc. SPIE 10072, Optical Diagnostics and Sensing XVII: Toward Point-of-Care Diagnostics, 1007212 (17 February 2017); doi: 10.1117/12.2253147
Show Author Affiliations
Michel K. Nieuwoudt, The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand)
The Univ. of Auckland (New Zealand)
The Dodd-Walls Ctr. for Photonic and Quantum Technologies (New Zealand)
Steve E. Holroyd, Fonterra Co-Operative Group (New Zealand)
Cushla M. McGoverin, Fonterra Co-Operative Group (New Zealand)
The Dodd-Walls Ctr. for Photonic and Quantum Technologies (New Zealand)
M. Cather Simpson, The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand)
The Univ. of Auckland (New Zealand)
The Dodd-Walls Centre for Photonic and Quantum Technologies (New Zealand)
David E. Williams, The MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand)
The Univ. of Auckland (New Zealand)


Published in SPIE Proceedings Vol. 10072:
Optical Diagnostics and Sensing XVII: Toward Point-of-Care Diagnostics
Gerard L. Coté, Editor(s)

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