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Austin, TX, United States

Ernst T.,Trace Evidence Unit | Berman T.,Orlando Regional Operations Center | Eckert-Lumsdon T.,U.S. Army | Olsson K.,Johnson County Crime Laboratory | And 5 more authors.
X-Ray Spectrometry | Year: 2014

Micro X-ray fluorescence (μ-XRF) spectrometry using an energy dispersive X-ray (EDS) detector is capable of detecting certain major, minor, and trace elements that permit potential discrimination of glass fragments in forensic cases on the basis of differences in elemental composition. Often, elements used for discrimination are present at concentrations near the detection limit of the EDS system, and the decision whether to utilize these minor peaks in a comparative analysis has generally been left to the discretion of the examiner. The use of signal-to-noise ratios (SNRs) of spectral peaks provides additional objectivity in peak identification/label decisions and in the selection of elements in semiquantitative ratio comparisons. In addition, the use of SNRs enables calculations of limits of detection and limits of quantitation and the monitoring of instrument performance, and facilitates performance comparisons of different μ-XRF configurations. This paper demonstrates a practical method for applying the concepts of SNR, limits of detection, and limits of quantitation to μ-XRF generated EDS-based spectra, discusses the implications of such determinations, addresses spectral features that must be considered when making the calculations, and illustrates the application of these concepts to the example of forensic examination and comparison of glass samples. © 2012 John Wiley & Sons, Ltd.

Cowan J.M.,Breath Alcohol Laboratory | Burris J.M.,Crime Laboratory | Hughes J.R.,Breath Alcohol Laboratory | Cunningham M.P.,Breath Alcohol Laboratory
Journal of Analytical Toxicology | Year: 2010

The relationship between normal body temperature, end-expired breath temperature, and blood alcohol concentration (BAC)/breath alcohol concentration (BrAC) ratio was studied in 98 subjects (84 men, 14 women). Subjects consumed alcohol sufficient to produce a BrAC of at least 0.06 g/210 L 45-75 min after drinking. Breath samples were analyzed using an Intoxilyzer 8000 specially equipped to measure breath temperature. Venous blood samples and body temperatures were then taken. The mean body temperature of the men (36.6°C) was lower than the women (37.0°C); however, their mean breath temperatures were virtually identical (men: 34.5°C; women: 34.6°C). The BAC exceeded the BrAC for every subject. BAC/BrAC ratios were calculated from the BAC and BrAC analytical results. There was no difference in the BAC/BrAC ratios for men (1:2379) and women (1:2385). The correlation between BAC and BrAC was high (r = 0.938, p < 0.0001), whereas the correlations between body temperature and end-expired breath temperature, body temperature and BAC/BrAC ratio, and breath temperature and BAC/BrAC ratio were much lower. Neither normal body temperature nor end-expired breath temperature was strongly associated with BAC/BrAC ratio.

Oostdik K.,Promega Corporation | French J.,Michigan State Police | Yet D.,Michigan State Police | Smalling B.,Sorenson Forensics | And 14 more authors.
Forensic Science International: Genetics | Year: 2013

As short tandem repeat markers remain the foundation of human identification throughout the world, new STR multiplexes require rigorous testing to ensure the assays are sufficiently robust and reliable for genotyping purposes. The PowerPlex® 18D System was created for the direct amplification of buccal and blood samples from FTA® storage cards and reliably accommodates other sample materials. The PowerPlex® 18D System allows simultaneous amplification of the 13 CODIS loci and amelogenin along with four additional loci: Penta E, Penta D, D2S1338, and D19S433. To demonstrate suitability for human identification testing, the PowerPlex® 18D System was tested for sensitivity, concordance, inhibitor tolerance, and performance with thermal cycling and reaction condition variation following SWGDAM developmental validation guidelines. Given these results, PowerPlex® 18D System can confidently be used for forensic and human identification testing.

Cope D.J.,Crime Laboratory | Dupras T.L.,University of Central Florida
International Journal of Paleopathology | Year: 2011

The present study evaluates a fetal skeleton (B532) from the Romano-Byzantine period Kellis 2 cemetery (circa A.D. 50-A.D. 450), in the Dakhleh Oasis, Egypt. This skeleton displays abnormal skeletal characteristics consisting of severe bowing of the long bones. Differential diagnoses using macroscopic and radiographic analyses indicate that this individual's pathological condition was caused by osteogenesis imperfecta (IO), possibly Type IIB/III, or Type IV OI, corroborating with characteristics reported in the clinical literature. Due to the severe bowing of the long bones, traditional aging methods could not be used for this individual. Baysian estimates of age indicate this individual was a fetus of approximately 38 weeks gestation. Although this condition has been diagnosed previously in the archeological literature, this burial represents the youngest aged example of osteogenesis imperfecta reported to date. © 2012 Elsevier Inc..

Kauppila T.J.,Aalto University | Flink A.,Aalto University | Pukkila J.,Crime Laboratory | Ketola R.A.,University of Helsinki
Rapid Communications in Mass Spectrometry | Year: 2016

Rationale Fast methods that allow the in situ analysis of explosives from a variety of surfaces are needed in crime scene investigations and home-land security. Here, the feasibility of the ambient mass spectrometry technique desorption atmospheric pressure photoionization (DAPPI) in the analysis of the most common nitrogen-based explosives is studied. Methods DAPPI and desorption electrospray ionization (DESI) were compared in the direct analysis of trinitrotoluene (TNT), trinitrophenol (picric acid), octogen (HMX), cyclonite (RDX), pentaerythritol tetranitrate (PETN), and nitroglycerin (NG). The effect of different additives in DAPPI dopant and in DESI spray solvent on the ionization efficiency was tested, as well as the suitability of DAPPI to detect explosives from a variety of surfaces. Results The analytes showed ions only in negative ion mode. With negative DAPPI, TNT and picric acid formed deprotonated molecules with all dopant systems, while RDX, HMX, PETN and NG were ionized by adduct formation. The formation of adducts was enhanced by addition of chloroform, formic acid, acetic acid or nitric acid to the DAPPI dopant. DAPPI was more sensitive than DESI for TNT, while DESI was more sensitive for HMX and picric acid. Conclusions DAPPI could become an important method for the direct analysis of nitroaromatics from a variety of surfaces. For compounds that are thermally labile, or that have very low vapor pressure, however, DESI is better suited. © 2016 John Wiley & Sons, Ltd.

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