Abstracts, Last Names M-Z
Abstracts are listed alphabetically by the last name of the speaker. Abstracts and speakers are subject to change; check this page regularly for additions and updates.
Further Adventures in Fluorescence
Charles Mazel — NIGHTSEA
As a developer of equipment for viewing and documenting fluorescence, NIGHTSEA encounters diverse opportunities and challenges in applying the technique. In the past year, we have worked with subjects including microplastics, planaria, cement, fingerprints, and bathroom towels. We have added fluorescence to platforms ranging from underwater vehicles to high-end digital microscopes at magnifications up to 2000x. This talk will review some of these experiences, what we have learned, and what we have developed.
The Curious Case of Asbestos Dental Tape
James R. Millette — Millette Technical Consulting
In 1976, after a review of death certificates, Menck and Henderson concluded in an article published in the Journal of Occupational Medicine that “Occupational groups found to be at excess risk (of asbestos disease) who have not been previously implicated included roofers, dental technicians….” Asbestos had been used in dental lining tape from the 1930s until the 1980s. The inner surface of a crucible or ring used in the “lost wax method” of casting dental prostheses was lined with the asbestos tape prior to casting at a high temperature. In 1977, dentists at the Army Institute of Dental Research in Washington used scanning electron microscopy (SEM) to find that asbestos fibers are released when ring liner was torn from a roll of asbestos by each of two laboratory workers. Our lab tests using polarized light microscopy (PLM), phase contrast microscopy (PCM), SEM, and transmission electron microscopy (TEM) showed chrysotile contents ranging from 40% to 95% in two brands of dental tape. Glove box testing of tearing the tape showed levels from 0.5 to 4 F/cc (fibers per cubic centimeter). Full chamber tests were 0.66 – 4.6 F/cc. Tests showed that more than 60,000 asbestos fibers (>5 µm long) were released during a single tear.
The Curious Case of the Yellowing Labels: An Investigation into the Discoloration of Package Labels
Brendan Nytes — Microtrace LLC
As a microanalytical laboratory, we encounter many different types of samples, with discolorations being one of them. They are typically easier to observe using the unaided eye and are often barely visible, if at all, by light microscopy. A seasoned microscopist understands that discolorations are a challenging endeavor that is often not straightforward. In some cases, they are just simply fine iron oxide particles imparting an amber color to a material. In other cases, the discoloration is the result of a diffuse color that is not composed of discrete particles. The use of extractions, fluorescence, and microanalytical techniques become essential in the identification of theses discolorations.
In this case example, we will discuss the presence of a yellow discoloration that developed on the surface of labels in a warehouse. The curious part was that the yellow discoloration was not uniformly present, seemed to develop randomly, and only appeared on labels in one particular warehouse.
A Survey of Analytical Considerations for the Elemental Analysis and Forensic Comparison of Automotive Paints by SEM-EDS
Christopher S. Palenik, Ethan Groves, and Lina T. Michely — Microtrace LLC
There is no doubt that the forensic comparison of paint based upon elemental analysis is probative, but the present ASTM guide on the forensic comparison of paint samples by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) offers little guidance on the impact that sample preparation, analytical parameters, and data evaluation have on the results. While both the theoretical underpinnings for the elemental analysis of materials by SEM-EDS and a practical approach to the comparison of paints have been well established, the theoretical and practical have never been married. For example, paint samples are often prepared with little attention to how sample preparation may impact analytical results; the analysis of a given paint layer is conducted with limited considerations for the impact of analytical parameters; and the criteria for associating or excluding samples is based on a subjective comparison of data with little understanding of significance. This talk will discuss various theoretical factors that should be considered in addition to the practical limitations that exist. Data from experiments will be presented to illustrate the impact such considerations may have on the interpretation and conclusions formed from the EDS analysis of paints.
The Burning Rock
Skip Palenik — Microtrace LLC
On a cold Thursday in Chicago, January 2018, a construction crew working on an empty lot on which a school was being built in the South Loop, was surprised when the walls of a trench they had just dug began to smoke. Smoking sewers are not an unusual site in the city during winter. The crew assumed this was due to the condensation of steam, until a backhoe was digging in the same area later in the day, and a piece of gravel that fell off the shovel began to emit white smoke, which suddenly became incandescent and burst into flame. At this point, the site was closed and an environmental firm was brought in to evaluate the safety of the situation. They had a rush analysis performed on the item at a local laboratory, which issued a five-page report (three of which were their credentials and certifications), showing the presence of several dozen elements and their quantities (by ICP-OES), in addition to a two-sentence result of their microscopical examination on one of the pages indicating that the sample looked like “wet drywall.” Because the report did not, understandably, solve the problem, we received a call to see what we might be able to do on Friday afternoon. The item was delivered to our laboratory early Saturday morning by a messenger from the environmental firm, and we began our analysis of it.
This presentation will describe the course of the analysis that we undertook that weekend, which led to the surprising solution to the problem and permitted work to begin at the site again on Monday. It will also explain why the substance responsible for the incident did not appear among the list of elements (amounting to almost half of the periodic table) in the report of the first analysis. This also helped illustrate the speaker’s warning that not all laboratories are the same.
The Technician: A Short-Lived 1940s Forensic Science Journal
William A. Randle — Missouri State Highway Patrol Crime Lab
John E. Davis was a well-known forensic scientist and director at the Oakland Police Department Crime Laboratory. What is not so well known is that he started his career at the Missouri State Highway Patrol Lab in Jefferson City, MO, and at that time, he also edited, published, and contributed to an early forensic science journal called The Technician, published from May 1943 to April 1944. This journal was unique for its time because it was written specifically for laboratory technicians working as forensic scientists and criminalists. This talk will present the lost volumes of The Technician and also provide some information about Mr. Davis.
The “Green” Movement and Paper Fiber Usage
Walter J. Rantanen — SGS-IPS Testing
The “Go Green” movement is promoted and embraced by environmental activists and supporters. This concept had also been adopted by many companies to encourage customers to use digital contact or records to replace the paper hard copy. Within the paper industry there have been fiber-type changes and sustainability claims to accommodate the “Green” narrative. In certain paper products, there are marketing labels claiming tree-free, non-wood plant fiber; natural fiber; cellulose fiber; recycled fiber; post-consumer waste fiber; sustainably sourced furnish; and other terms. Some claims specify fiber types that may be popular with many consumers such as bamboo, hemp, wheat straw, and cotton. Some of these claims may be suspect or partial truths. Light microscopy is usually the best method to confirm, refute, or understand the claimed contents in paper products.
Solving Problems with Chemical Microscopy
John A. Reffner — John Jay College, CUNY
Happiness lies in the joy of achievement and the thrill of creative effort. Microscopy provides true happiness by providing the means to observe the micro world, creating beautiful images, and for solving problems. I’ll share a few examples of the joy I have achieved and the thrill of creative effort that I have experienced. For instance, I became my daughter’s hero when, aided by a magnifying glass and needle-nose tweezers, I skillfully removed a small glass fragment from her foot. In another example, I was introduced by Dr. Roy P. Allen to his method for differentiating carbon blacks by their color. Carbon black rubber samples were made as reference standards. These were used to analyze other black rubber samples. Small fragments of each rubber and a small drop of mineral oil was placed on a microscope slide. A second slide placed on top. Pressure forced the two pieces of black rubber to come together. For rubbers containing the same carbon black, the colors were indistinguishable. I was happy when I applied this technique to solve a problem involving a conducting carbon black. I hope sharing my experiences will stimulate open discussion of favorite stories from the audience of chemical microscopists.
Discriminating Glass Fragments Using Micro-XRF Spectrometry with Polycapillary Optics
Bruce Scruggs — EDAX, Inc.
Glass fragment analysis is a common problem found in forensic and industrial laboratories. The typical issue is to compare glass fragments from a known source to an unknown source and show that the unknown fragments are either elementally consistent or inconsistent with the known fragments. There are various characterization tests available, including optical methods, physical methods, and elemental analysis. Micro-XRF spectrometry has been widely used for elemental analysis because it is non-destructive, it has acceptable detection limits, and data acquisition can be run unattended.
XRF intensity ratios are commonly used in U.S. forensic labs according to ASTM E2926-13 for window glass fragment comparisons. The method is commonly implemented using one set of spectral acquisition conditions to collect XRF spectra. This presentation demonstrates the use of multiple acquisition conditions to optimize data collection over different energy ranges. The analysis is facilitated by using polycapillary X-ray optics with spot sizes <100 μm FWHM, while generating high signal intensities for improved detection limits. The goal for this collection methodology is to eliminate spectral artifacts that may complicate comparisons of desired trace elements while maintaining good detection limits for the most important elements involved in the comparisons.
Development of Modern Microcrystal Tests for Controlled Drugs, Diverted Pharmaceuticals, and Bath Salts: Project Update
Sebastian B. Sparenga — McCrone Research Institute
Beginning in 2016, McCrone Research Institute began a research project, awarded by the National Institute of Justice (2015-IJ-CX-K010), to discover and develop microcrystal tests for a number of emerging drugs and pharmaceuticals that were seeing a marked increase in abuse. After two years of research, successful microcrystal tests for 10 additional drugs have been developed. Each new microcrystal test includes recommended protocols and morphologies of crystals including photomicrographs, infrared spectra of microcrystal precipitates, potential interferences, and optical crystallographic properties of the resultant microcrystals and will be included in A Modern Compendium of Microcrystal Tests for Illicit Drugs and Diverted Pharmaceuticals, originally published by McCrone in 2015. This presentation will discuss the current progress and examine what is still needed for project completion.
Measurement of Nanoparticle Size Using Transmission Electron Microscopy
Jacob M. Spry and Richard S. Brown — MVA Scientific Consultants
This presentation addresses challenging tasks associated with achieving quality measurements of various nanoparticles using transmission electron microscopy (TEM). Critical to the imaging and sizing process is the preparation of the sample prior to transfer to a TEM grid. Preparing nanomaterials in such a way that will minimize agglomeration and allow for reliable sizing of individual nanoparticles is critical. Various methods will be discussed, such as the media and physical separation methods utilized for nanoparticle dispersion, additional agents that can be added to suspensions to further improve dispersion quality, and methods used to transfer nanoparticle suspensions to TEM grids. TEM imaging methods will also be explained, including selection of quality regions for imaging, identifying a suitable magnification for sizing, and maximizing image quality for accurate particle sizing. Finally, image sizing will be discussed, including software utilized for nanoparticle sizing, criteria considered when sizing nanoparticles, and discerning particles compared to potential particle agglomerates during the sizing process. Examples of various nanoparticle TEM preparations will be shown, to illustrate the various challenges.
Creating an Aqueous Precipitation and Crystal Table for Microcrystal Tests of Common Illicit Drugs
Casey Turney — University of Illinois at Chicago Forensic Science Program; and McCrone Research Institute
Microcrystal tests are chemical precipitation tests using a variety of aqueous reagents to identify various drugs using a polarized light microscope. Thirty-four microcrystal test methods were checked for unique microcrystal formation with 21 different drugs. These tests were selected from A Modern Compendium of Microcrystal Tests for Illicit Drugs and Diverted Pharmaceuticals, published by McCrone Research Institute. The results were tabulated for easy access and for use as an identification tool in forensic science laboratory settings. Of the 21 drugs in the table, two of the microcrystal test results using picric acid and dilituric acid reagents for methylphenidate and pseudophedrine, respectively, are difficult to interpret and additional microscopical characterization or alternate microcrystal tests may be required for their identification.
Problems in Raman and FTIR Spectral Library Searches
Lawrence Wayne — Forensic Analytical Laboratories, Inc.
Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) frequently rely on search libraries to identify an unknown substance. While analysts are usually familiar with the inherent limitations of the use of spectral libraries, their use is based on the assumption that the libraries have been prepared, examined, and labeled properly. Examination of many available libraries, private and commercial, has revealed library spectra that are either poorly collected or mislabeled entirely. This may result in misattribution or misidentification of an unknown substance. Examples of poor quality and incorrectly labeled spectra will be presented, together with suggested methods to reduce the possibility of misidentification due to poor library quality.
Image Acquisition and Analysis of Soybean Stem Sections
Aryeh Weiss — Faculty of Engineering, Bar Ilan University, Ramat Gan, Israel
Anne Alerding — Department of Biology, Virginia Military Institute, Lexington
Soybeans are among the major agricultural crops planted in the United States, with a total production of 4.39 billion bushels in 2017. Over the last decade, production research efforts have been unable to create soybean cultivars that consistently surpass 40 bushels per acre in Virginia fields. Improving yields requires new directions in production research. As part of this work — and in order to understand the influence of plant tissue morphology on new branch growth (cell and cell wall synthesis) and seed abortions — we are studying the growth of tissues in the stem using brightfield and fluorescence imaging. In these studies, tiled, large-area transmitted light and fluorescence images of histoslides of stem cross-sections were acquired, stitched, and analyzed using the Fiji version of ImageJ.
In this talk, acquisition and subsequent image processing workflows will be presented, and the following topics will be discussed:
1. Segmentation of brightfield color images, using color deconvolution.
2. Acquisition of large area fluorescence, and the advantages of fluorescence over brightfield imaging.
3. Segmentation of the fluorescence images, using spectral unmixing.
4. A tool that can be used to determine optimal combinations of objective magnification and numerical aperture, relay optics magnification, and camera properties.
Product Discoloration: Analysis of an Unknown Red Colorant
Katie M. White and Christopher S. Palenik — Microtrace LLC
In the manufacturing industry, unwanted discoloration can result from many different mechanisms, including charring, chemical change, and transfer of a liquid or fine particles. Regardless, our analytical approach typically begins with a microscopical examination of the sample. When discrete colored particles are observed and suspected to be pigment, Raman spectroscopy is an ideal analytical tool for characterization. In situ analysis can be particularly useful for pigments, but interferences with the sample matrix may require further isolation of the colorant for analysis.
Some discolorations are submitted to us as complete unknowns, and we rely on our spectral reference library to determine possible sources for the colorant. In other cases, clients come to us with a suspected source in mind, but before a definitive association can be made, the known colorants must be characterized and compared to the unknown sample.
This presentation will discuss our analysis of a discolored chemical product submitted to our laboratory for identification and comparison to a known source. It will also demonstrate the importance of subtle differences when comparing Raman spectra. Additional case examples involving pigment identification will be highlighted.