On April 25th, 2012 we hosted a live webinar titled “Laboratory Methods for the Examination of Foreign Particulate Matter.” During the webinar our presenters, David Exline, Senior V.P. and Antonio Scatena, Scientist at Gateway Analytical, discussed current methods of particulate isolation, laboratory testing methods for identifying foreign particulates and the company’s forensic approach to source determination. During the webinar we received a number of questions, below is a sample of the Q&A session at the end of the webinar.
Here is a sample of the Q&A from this webinar, with David Exline and Antonio Scatena:
Q: What is difference between characterization and identification?
A: In my opinion, characterization refers to the general classification of materials, and often times a determination of the actual type of material such as nylon or even to sub-classification such as nylon 6 or nylon 66. The classification of a paint particle to include its type, such as acrylic or latex, can be achieved leading to potential sources such a architectural paints. Metals can also be characterized as not just steel, but may be sub-classified as to specific type. In the event that a particular particle can be associated to a specific source, then this would be classified as identification.
Q: Can you provide suggestions on sample shipment? How to avoid breakage or contamination during shipping and handling?
A: Sample isolation and preservation is critical to the analysis. We recommend isolating a particulate in welled microscope slides, cover it with a normal microscope slide and tape it together. This allows the particle to be preserved for initial particle inspection, but also allows for easy removal for more in-depth testing without crushing or losing the samples. Secondary containment of the slides into slide holders should be employed for shipping.
Q: How much PLM do you use to ID unknowns? If you read McCrone’s writings, most identifications can be done with PLM, has this been your experience?
A: My experience is that PLM is a vital tool for particle characterization and the information gained is crucial to the initial characterization of the material. However, more intensive analytical testing is recommended for a complete multi-analytical characterization that provides additional information about the sample and provides supporting analytical testing data to confirm PLM but also provides important support documentation for identification purposes.