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How Do Microscopy Methods Reveal the Source of Trace Contaminants? (Food Safety)

Craig S. Schwandt, Ph.D.
Food Safety – August 11, 2015

Any stage of the production process can introduce contaminants or adulterants, and their manifestation might seriously affect the safety of the final product. Microscopy-based methods can provide imaging that conveys much more information about how the contamination came to be present in the product rather than simple concentration values, and can also identify the contaminant. Establishing the physical state of the contaminant is also essential to determining a proper analytical approach, ultimately providing results to mitigate future occurrences.

Diagnosing a Method

The characteristics and morphology of a solid phase contaminant help establish its source and create an early, formal record. The first distinction should be whether a contaminant is mixed indiscernibly into the final product or whether it occurs as discrete particles. In the U.S., the Food and Drug Administration (FDA) prescribes various bulk analytical methods for raw ingredients and final products. When a solution introduces elemental or organic compounds to the product or a process mixes these contaminants at the molecular level, bulk analysis methods are appropriate. FDA determines relative safe exposure levels for trace concentrations of these compounds. Unfortunately, bulk analysis methods are destructive and provide minimal clues as to the source of contamination.

In contrast, when contaminants exist as particles discrete from the product, an opportunity opens to characterize, identify and find an explanation for these contaminants before destructive analyses. In many instances, further bulk analyses are not even required.

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