Isolating contaminant particulate begins with the use of an optical stereo zoom microscope. Visual inspection of an adulterated sample, in comparison to a reference sample, usually reveals a great deal about the contaminant, especially if it is particulate in nature. For example, metal contamination may occur as large pieces easily visible to the unaided eye, or as gray, brown, or orange (and sometimes green) spots in the product. The contaminant material can be isolated from the product under magnification using custom tools for handling microscopic size samples. A microscopic subsample can then be mounted on a suitable substrate for further analyses and identification. Continuing with the metal particulate example, inspection of the discolored samples with scanning electron microscopy (SEM) and X-ray microanalysis using an energy or wavelength dispersive spectrometer system (EDS or WDS), may reveal that the discolored areas contain micrometer sized particles of metal, even gauging the extent to which they have oxidized. X-ray microanalysis can establish the alloy type, allowing the manufacturer to narrow the search based on the product’s exposure to machinery composed of different alloys. This method of isolation and analysis is so powerful that sometimes the source of contamination can be traced to non-standard replacement parts installed by unqualified repair technicians.
In instances where polymers or other organic compounds are the contaminants, isolating these particles and pressing them out onto potassium bromide crystals for microscopy-based infrared spectroscopy yields amazing identification success.
When additional information is required, other methods provide a wide range of information about the nature of the particulate. These methods include micro X-ray diffraction, Raman microspectroscopy, transmission electron microscopy, electron spectroscopy for chemical analysis, and some mass spectrometry methods geared toward surface analysis.
Once particulate contaminants are isolated and fully characterized with multiple microscopy-based methods, it is generally easier to deduce how the contaminants came to be in the sample. This knowledge allows the product producer to correct the contamination issue at its source.
Collaborating with a Forensic Laboratory
Manufacturers and producers have a couple options when it comes to addressing their FSMA contamination identification requirements. The first is to construct an in-house laboratory capable of meeting the requirements in terms of competency, training and accreditation. The second is to utilize the services of third-party laboratories that are already accredited and ready to meet the quality requirements necessary for successful scrutiny by the FDA. Although many U.S. contract laboratories advertise compliance to current Good Manufacturing Practices (cGMP), a growing number of companies are operating at a global level and, therefore, need facilities that meet global standards. As such, meeting ISO standards is becoming a widely accepted and recognized quality program. ISO/IEC 17025:2005 covers the general requirements for the competence of testing and calibration laboratories, which includes elements beyond cGMP requirements. For ISO accreditation, a laboratory develops their quality program and then becomes accredited after inspection and approval by an ISO-recognized inspection company. With this system, manufacturers and producers can easily select an accredited laboratory to conduct their contaminant analysis and rest assured that the samples were analyzed using methods meeting the globally recognized ISO quality standard.
FSMA mandates more stringent measures to identify food product contaminants and their sources, established through testing. Forensic or investigational analysis has a recognized history of successfully helping the pharmaceutical industry meet similar FDA requirements for contamination. Many contaminants are actually particulate-scale materials that can be easily identified and their origin subsequently established using multiple microscopy methods. When contamination is an issue, using an ISO 17025 accredited laboratory can simplify meeting the full FSMA requirements.
Dr. Schwandt is a senior research scientist and director of industrial services at McCrone Associates, Inc., and co-teaches several courses at Hooke College of Applied Sciences, LLC, Westmont, Ill. Reach him at firstname.lastname@example.org.