Electrochemiluminescence (ECL) is a highly sensitive detection technique; however, its inherently low selectivity is a significant challenge in analytical and sensing applications. In this study, we developed a system for the specific determination of the pharmaceutical bromhexine (BH). In this system, ECL was combined with a molecularly imprinted polymer (MIP) capable of molecular recognition. A BH-template-based MIP-modified electrode, synthesized by electrolytic polymerization, was prepared. Interestingly, the MIP-modified electrode robustly immobilized the template molecule via peroxidation during electrolytic synthesis. The sensitivity was approximately three times that without further oxidation. X-ray absorption fine structure measurements were performed using synchrotron radiation to characterize interactions between the analyte and the polymer. From the results, a complex mechanism involving hydrogen bonding, π-π interactions, and halogen-π interactions was inferred between the analytical chemical species and the polymer. The fabricated MIP-modified electrode was applied to determine BH in commercially available pharmaceuticals, prescription drugs, and biological urine samples. The results were compared with those from liquid chromatography-mass spectrometry. This system shows potential for development into a selective sensor.

Fingerprint testing is routine for personal identification, but damaged prints, such as those exposed to heat in fire cases, are difficult to visualize. Currently, there is no method available to visualize severely heat-damaged fingerprints. We developed a visualization technique using synchrotron radiation (SR) soft-X-ray photoemission electron microscopy (PEEM). Fingerprints on silicon, stainless steel, aluminum, brass, and glass were heated at 400 degrees C for an hour and then examined. Ridge patterns could not be seen by optical microscopy, laser microscopy, or scanning electron microscopy, except on silicon. Even then, SR PEEM revealed ridge patterns by detecting sodium particles (similar to 1 mu m) clustered into 10 mu m spots. Multiple images were combined to successfully produce a clear 5 mm-wide ridge pattern. For the glass substrate, prior titanium vapor deposition prevented electric discharge, resulting in a clear ridge pattern observation by SR PEEM. Unlike conventional methods, SR soft-X-ray PEEM detects sodium sensitively and specifically, producing clear ridge patterns in heat-damaged fingerprints, which is promising for advanced criminal fingerprint testing.

Two kinds of globotriaosyl (Gb3) trisaccharides (1 and 2) with an azido (−N = N = N) group at the end of an aglycon oligoethylene glycol group (EG3 for 1 and EG12 for 2) were prepared. Each of the Gb3 products was immobilized on a silicon nitride (SiN) chip with a Huisgen coupling reaction. The derived Gb3/SiN chips were applied as sensor chips in a microfluidic flow system using reflectometric interference spectroscopy (RIfS). When examined with Escherichia coli O157 Shiga toxin (Stx1) as the target toxin and bovine serum albumin (BSA) as the negative control, the microfluidic RIfS analysis has indicated that Gb3/SiN chips with the elongated EG12 group can suppress a non-selective adhesion of BSA more effectively than those with an EG3 linker. A spike and recovery test using a Japanese cucumber salad has indicated that chromophoric substances contained in foods interfere with the direct RIfS detection of Stxs. This problem was circumvented by a centrifugal filtration process for each of the test samples in advance of the RIfS detection. The pretreated samples make clear RIfS responses to the target Stx1 bound on the surface of the Gb3/EG12/SiN chip with a detection sensitivity in a 0.1 0.5 µg/mL range by LOD. One analysis completes within 25 min after the centrifugal filtration process. The microfluidic RIfS detection of Stx1 also applies to test samples taken from an E. coli selective cultivation medium (EC broth), meaning that it will provide a promising tool for determining STEC and other Stxs-producing bacteria that may contaminate various foods other than the Japanese salad.

The identification of single acrylic fibers is critical in forensic science. Spinning solvents and dyes containing zinc are used to produce acrylic fibers. However, the information has not been used to identify acrylic single fibers for forensic purposes. This study aimed to discriminate between single acrylic fibers by focusing on zinc. A single type of red acrylic fiber from the Forensic Science Fiber Collection (Microtrace LLC, USA) was used as the standard sample. In contrast, nine commercially available colored acrylic fibers were used as samples. Owing to the limited beam time of synchrotron radiation X-ray analysis, total reflection X-ray fluorescence (TXRF) was used as a trace element screening method. Nanobeam synchrotron radiation X-ray fluorescence (SR-XRF) imaging of thinned acrylic single-fiber cross-sections was conducted to visualize the distribution of trace elements within a single fiber. X-ray absorption fine structure (XAFS) analysis was conducted to investigate the chemical states of zinc in the single acrylic fibers. The nanobeam SR-XRF imaging enabled the visualization of zinc derived from dyes and spinning solvents in single-fiber cross-sections. The images were classified into three distinct patterns. Two types of X-ray absorption near edge structure (XANES) spectra of the zinc absorption edge, reflecting the difference in the chemical state of zinc, were obtained from the acrylic single-fiber sample. In conclusion, the distribution and chemical state of zinc were found to be powerful indicators for distinguishing single acrylic fibers.

BACKGROUND:Hexahydrocannabinol (HHC) and its analogs are recent additions to semi-synthetic cannabinoids in the recreational drug market. Here, the metabolism of 18 HHC analogs was compared to gain a comprehensive understanding of the structure-metabolism relationship of HHC analogs and to identify urinary biomarkers. Additionally, an authentic urine sample obtained from a suspected hexahydrocannabiphorol (HHCP) user was analyzed. METHODS:Both 9(R)- and 9(S)-epimers of HHC and 8 analogs were separately incubated with human liver microsomes (HLMs) for 1 h. The resulting products and the urine sample were analyzed by liquid chromatography-high-resolution mass spectrometry in an untargeted approach. RESULTS:The metabolites were generated by hydroxylation, dehydrogenation, ketone formation, carboxylation, or hydrolysis, either alone or in combination. Concerning the HHC homologs, for 9(R)-epimers, metabolites with multiple biotransformations, e.g., dihydroxy metabolites, were generally more abundant, and the percentage of hydroxy metabolites tended to increase for the longer side-chain homologs, while the reverse was observed for dihydroxy metabolites. For 9(S)-epimers, a metabolite hydroxylated at the methylcyclohexyl moiety was by far the most abundant metabolite, with similar behaviors among hexahydrocannabivarin, hexahydrocannabutol, and HHC, and between hexahydrocannabihexol and HHCP. Acetylated analogs initially underwent hydrolysis to produce almost identical metabolic profiles as the non-acetylated analogs. Methyl ether analogs did not appear to show any particular metabolic trend. In the clinical urine sample, 3 HHCP (di-)hydroxylated metabolites were detected, matching the HLM results. CONCLUSIONS:The revealed structure-metabolism relationship could serve as a reference for investigating the metabolism of similar cannabinoids, while the identified biomarkers could facilitate drug testing.

Codeine is a common analgesic drug that is a pro-drug of morphine. It also has a high risk of abuse as a recreational drug because of its extensive distribution as an OTC drug. Therefore, sensitive and selective screening methods for codeine are crucial in forensic analytical chemistry. To date, a commercial analytical kit has not been developed for dedicated codeine determination, and there is a need for an analytical method to quantify codeine in the field. In the present work, potential modulation was combined with electrochemiluminescence (ECL) for sensitive determination of codeine. The potential modulated technique involved applying a signal to electrodes by superimposing an AC potential on the DC potential. When tris(2,2'-bipyridine) ruthenium(II) ([Ru(bpy)(3)](2+)) was used as an ECL emitter, ECL activity was confirmed for codeine. A detailed investigation of the electrochemical reaction mechanism suggested a characteristic ECL reaction mechanism involving electrochemical oxidation of the opioid framework. Besides the usual ECL reaction derived from the amine framework, selective detection of codeine was possible under the measurement conditions, with clear luminescence observed in an acidic solution. The sensitivity of codeine detection by potential modulated-ECL was one order of magnitude higher than that obtained with the conventional potential sweep method. The proposed method was applied to codeine determination in actual prescription medications and OTC drug samples. Codeine was selectively determined from other compounds in medications and showed good linearity with a low detection limit (150 ng mL(-1)).

A number of synthetic cannabinoids have been appearing in the recreational drug market for more than a decade. Recent additions are so-called semi-synthetic cannabinoids, and they structurally closely resemble the main psychoactive component of cannabis, Δ9-tetrahydrocannabinol. Knowledge of new (semi-)synthetic cannabinoids is essential to help identify them in authentic forensic case samples. Therefore, the aim of the study was to examine two commercially available electronic cigarette liquid products claiming to contain cannabinoids and characterize the structures of the main compounds. The liquid products were analyzed by gas chromatography-mass spectrometry (GC-MS), GC-quadrupole time-of-flight mass spectrometry (GC-QTOF-MS), and liquid chromatography-high-resolution mass spectrometry (LC-HRMS). In product A, typical cannabinoids (cannabidiol, cannabigerol, and cannabinol) and terpenes (α-caryophyllene and β-caryophyllene) were identified by comparison with reference materials. An unknown peak was isolated by semi-preparative high-performance LC, analyzed by nuclear magnetic resonance (NMR) spectroscopy, and identified to be Δ9-tetrahydrocannabihexol acetate (Δ9-THCH-O). To the authors' knowledge, this is the first report of the identification of Δ9-THCH-O in commercially available products. Another compound estimated as cannabihexol acetate was also detected. In product B, cannabidiol, cannabinol, α-caryophyllene, and β-caryophyllene were identified, while two unknown peaks were estimated as tetrahydrocannabidiol isomers. Despite products A and B being labeled to contain "60% HHCPM" and "80% 10-OH-HHC," respectively, no such compounds were detected. The findings of this study could help detect Δ9-THCH-O in case samples and highlight the need to keep monitoring commercial products to identify new drugs, while warning that the package labels cannot be trusted.

The wireless power transfer (WPT) technique is a unique safe electric power supply system. In this study, we designed a simple analytical system that combines electrochemiluminescence (ECL) measurement with WPT for illegal stimulant methamphetamine (MA) detection. The WPT-ECL system, which consists of a commercially available inexpensive driving coil and a commonly available enameled wire, was used to screen MA with an easy procedure. The prototype WPT-ECL measurement system observed a clear ECL response by incorporating an inexpensive rectifying diode, and MA was determined in the range to 500 mu M with the detection limit of ca. 15 mu M (S/N =3). The MA detection protocol under WPT-ECL measurement was characterized; it was expected to be a simple and cost-effective analytical technique without complex circuitry, such as full-wave rectification. The proposed WPT-ECL system was applied to an actual urine sample. MA addition and recovery experiments on three volunteer urine samples showed good reproducibility with an RSD of less than 6 %, resulting in good agreement with the LC-MS results. The WPT-ECL system was expected to enable non-specialist investigators to simple detection procedures of MA, with the aim of practical application to forensic toxicology analytical scenes.

Botulinum neurotoxins (BoNTs), ricin, and many other biological toxins are called AB toxins possessing heterogeneous A and B subunits. We propose herein a quick and safe sensing approach to AB toxins based on their unique quaternary structures. The proposed approach utilizes IgG antibodies against their A-subunits in combination with those human cell-membrane glycolipids that act as the natural ligands of B-subunits. In practice, an IgG antibody against the A-subunit of a target toxin is selected from commercially available sources and immobilized on the surface of Au nanoparticles to constitute a multivalent IgG/Au nanoconjugate. The derived IgG/Au conjugate is used in the pretreatment process of test samples for deactivating biological toxins in the form of a ternary toxin/antibody/Au complex. This process is implemented in advance to reduce the risk of handling biological toxins in laboratory work. On the other hand, the human glycolipid is immobilized on a tiny glass plate and used as a biosensor chip. The biosensor chip is set in the chamber of a flow sensing system using localized surface plasmon resonance (LSPR) spectrometry available in portable size at relatively low cost. In principle, the LSPR sensing system enables us to perform a rapid and selective detection for different kinds of biological toxins if the human glycolipid is correctly selected and installed in the sensing system. In the present LSPR sensing approach, a target AB toxin may have been deactivated during the pretreatment process. The test sample containing the deactivated AB toxin becomes a real target to be analyzed by the sensing system. In the present, we describe the concept of employing the commercially available IgG antibody in the pretreatment process followed by a typical procedure for converting it into the multivalent antibody/Au nanoconjugate and its preliminary applications in the LSPR detection of a ricin homologue (RCA120) and BoNTs in different serotypes. The tested LSPR sensing approach has worked very well for the ricin homologue and certain serotypes of botulinum neurotoxins like BoNT/A, indicating that the prior deactivation process at their A-domains causes no significant damage to the function of their B-domains with respect to determining the host cell-membrane glycolipid. The experimental results also indicated that LSPR responses from these pretreated AB toxins are significantly amplified. That is obviously thanks to the presence of Au nanoparticles in the multivalent IgG/Au nanoconjugate. We suggest in conclusion that the proposed LSPR sensing approach will provide us with a safe and useful tool for the study of biological AB toxins based on their unique quaternary protein structures.

Poly(1,2-difluoroethylene) (PVLF, -[CHFCHF](n)-), a member of representative fluorine polymers, was synthesized about half a century ago by the gamma-ray-irradiated radical polymerization reaction as well as by the emulsion polymerization reaction (Durrell et al.). The thus-polymerized PVLF was reported to be atactic and amorphous according to the analysis of its F-19-NMR data and X-ray diffraction data (not given). In the present report, we have successfully synthesized PVLF by a different type of radical polymerization reaction in solution. The newly measured F-19-NMR spectral profile was essentially the same as that before. The solution-cast and melt-quenched samples were almost amorphous as known from the X-ray diffraction measurements. However, once the samples were heat-treated above the glass transition temperature (about 100 degrees C), sharp X-ray diffraction peaks were observed to appear. The differential scanning calorimetry (DSC) data exhibited a clear endothermic peak at around 200 degrees C, corresponding to the melting point. In addition, the thermal, mechanical, and physicochemical properties of this newly synthesized PVLF sample have been investigated by means of wide-angle X-ray diffraction, small-angle X-ray scattering, infrared absorption spectra, DSC, and viscoelastic data. All these experimental data revealed that PVLF is a semicrystalline polymer, not totally amorphous as had been reported before, and it exhibits various characteristic behaviors. PVLF had been forgotten because of its long-time misunderstanding as an amorphous polymer species. However, the present study has allowed PVLF to become a new member of crystalline fluorine polymers.

In the recreational drug market, synthetic cannabinoids with a new acetamide linker structure emerged, most likely to circumvent the law. As the knowledge of drug metabolites is vital for proving drug consumption, the phase I metabolism of the newly emerging cannabinoids, ADB-FUBIATA, AFUBIATA, CH-FUBIATA, and CH-PIATA, was investigated. Each drug (10 μmol/L) was incubated with human liver microsomes for 1 h, and the samples, after dilution, were analyzed by liquid chromatography–high-resolution mass spectrometry. All drugs were metabolized via hydroxylation and N -dealkylation, while AFUBIATA and CH-PIATA additionally underwent ketone formation. The metabolites AF7 (hydroxylated at the indole/adjacent methylene) of ADB-FUBIATA, A16 (hydroxylated at the adamantane) of AFUBIATA, CF15 (hydroxylated at the cyclohexane) of CH-FUBIATA, and CP9 (hydroxylated at the pentane) of CH-PIATA were the most abundant metabolites by considering the peak areas on the chromatograms, and are recommended for urinalysis. The structure–metabolism relationship was also discussed, which generally agreed well with previously reported metabolic pathways of other synthetic cannabinoids. However, the preferred hydroxylation site of ADB-FUBIATA, the indole/adjacent methylene, clearly differed from that of ADB-FUBICA, the 3,3-dimethylbutanamide moiety, despite their structures differing only by a methylene group, emphasizing that metabolic predictions of new drugs should not replace in vitro experimental analyses, albeit helpful.

Glycolipid chips having a double layer of Au nanoparticles are proposed for detection of biological toxins. The sugar-modified chips constitute an under and an upper layer of Au nanoparticles of 20-80 nm diameter on glass plates, and Au nanoparticles of each layer are linked with 1,8-octanedithiol by a self-assembled monolayer (SAM) technique. A tris-sialo glycosphingolipid, ganglioside GT1b, having lipoic amide at the sphingosine part was immobilized on the Au outside surface of the upper layer, and botulinum toxin (type A heavy chain) was detected by localized surface plasmon resonance (LSPR). The GT1b-Cer-coated chip having a double layer of Au nanoparticles enhanced the toxin detection by LSPR more than those with single monolayers. The LSPR response changed according to the sizes of Au nanoparticles in each under and upper layer. The combination of 60 and 40 nm Au nanoparticles in the under and upper layer, respectively, gave the best result, which enabled the toxin detection at concentrations below 5 ng/mL with the portable LSPR device.

The quantitative evaluation of the drug mixing condition was conducted for application in the forensic discrimination of drug powders using micro Fourier transform infrared (FT-IR) spectroscopy. Bromhexine hydrochloride (BHCl) and p-hydroxybenzoic acid (PHBA) were used as the simulated drug and additive, respectively. Equal masses of two chemicals were (1) simply mixed, (2) homogenized using agate mortar, or (3) dissolved in methanol and dried, and then (4) homogenized using agate mortar. The mixed powders dispersed on BaF2 plates were subjected to mapping analysis of micro FT-IR spectroscopy using synchrotron radiation (SR) or globar light in transmission mode with aperture sizes of 2.5 x 2.5 and 10 x 10μm2, and x-y scanning steps of 2.5 and 10 μm, respectively. The areas of the vibration bands specific to BHCl (C-N bending) and PHBA (C=O stretching) were converted to the molar contents (CBHCl, CPHBA), and the relative content ratio (RCR: CPHBA/[CBHCl + CPHBA]) was used as one mixing parameter. The resulting two-dimensional distribution map provided the relative spatial localizations of the two species, and frequency histograms with a horizontal axis of RCR were plotted to evaluate the RCR distribution. The percentage frequency of the extreme value in which RCR was 0 or 1 (%EV) was used as one mixing index. After excluding the extreme values, the coefficient of variation (CV) of the RCR distribution was used as another mixing index. The differentiation among four mixing modes could be evaluated from the standpoint of %EV and CV, and the discrimination capacity by SR instrument was superior to that by globe light instrument.

Synthetic cannabinoids are one of the most popular classes of recreational drugs and following China's class-wide ban on the existing synthetic cannabinoids, a new series of synthetic cannabinoids, known as "OXIZID", with major structural modifications to circumvent the law have started to be found on the drug market. Although the structures of newly emerging drugs of abuse need to be characterized for forensic (and subsequently even clinical testing) purposes, these characterizations are often impeded by the fact that synthesizing reference standards can be demanding and/or nuclear magnetic resonance spectroscopy requires a relatively large amount of sample (i. e., milligrams). Here, we report the structure determination of six synthetic cannabinoids, OXIZIDs (BZO-POXIZID, 5F-BZO-POXIZID, BZO-4en-POXIZID, and BZO-HEXOXIZID), AKB48, and JWH-424, using the crystalline sponge method via single crystal X-ray diffraction (SC-XRD). The crystal structures for all but BZO-HEXOXIZID are reported for the first time. The crystalline sponge method successfully revealed the structures of the six cannabinoids by soaking only 1-5 mu L solution containing 1-5 mu g drug into a porous crystal and subjecting the soaked crystal to SC-XRD. Among them, the structure determination of JWH-424 (an oily and non-crystalline compound) demonstrated the ability of the method to allow not only the visualization of three-dimensional structures but also the structure determination of non-crystalline compound. Therefore, the crystalline sponge method has great potential for an effective structural determination of synthetic cannabinoids, especially when the cannabinoids cannot readily be crystallized.

Discrimination of single fibers is important in forensic investigation. Conventional microscopic observation and analytical methods such as micro-Fourier transform-infrared spectroscopy, a suitable technique for polymer component identification, can discriminate single white fibers made from different polymers. Polyesters contain metal compounds derived from polymerization catalysts, transesterification catalysts, and matting agents. Here we propose a forensic method for discriminating white-based polyester single fibers. The X-ray intensity ratios, distribution of metal elements, and chemical states are identified by semi-microbeam X-ray fluorescence (XRF) spot analysis, nanobeam XRF imaging, and X-ray absorption fine structure analysis (XAFS) utilizing synchrotron radiation, respectively. The analytical specimens were white-based polyester single fibers from the standard forensic fiber collection (Microtrace LLC, USA) and commercially available polyester products. Semi-microbeam XRF spot analysis detected metallic elements such as Ti, Mn, Co, Ge, and Sb derived from polymerization catalysts, transesterification catalysts, and matting agents. The X-ray intensity ratios of Ti/Mn, Ti/Ge, Ti/Sb, and Mn/Sb were obtained with good reproducibility but those of Ti/Co, Mn/Co, and Co/Sb, which are related to cobalt, were lowly reproducible in some samples. The poor reproducibility of the cobalt-related X-ray intensity ratios was attributed to uneven distributions of the metallic elements in the polyester single fibers, as visualized by nanobeam XRF imaging. The images showing elemental heterogeneity have proven to be good markers for identification. The XAFS results showed that three types of Ti compounds and two types of cobalt compounds are utilized in different applications of polyester single fibers; moreover, the chemical states are useful indices of single-fiber discrimination.

A new class of synthetic cannabinoids termed OXIZIDs has recently emerged on the recreational drug market. In order to continue the detection of new drugs in biological specimens, the identification of metabolites is essential. The aim of this study was to elucidate the metabolites of BZO-4en-POXIZID produced in human liver microsomes (HLMs) and human hepatocyte incubations and to compare the results with closely related analogs using the same experimental setup. Each drug was incubated for 1 h in HLM and BZO-4en-POXIZID was also incubated in human hepatocytes for up to 3 h. Subsequently, the incubates were analyzed by liquid chromatography-high-resolution mass spectrometry. BZO-4en-POXIZID metabolites were obtained in the incubation with HLMs and human hepatocytes, via the metabolic pathways of dihydrodiol formation, hydroxylation, reduction of the alkene bond and glucuronidation. The major metabolic pathway was found to be dihydrodiol formation at the pentenyl tail moiety. BZO-POXIZID, 5 F-BZO-POXIZID, BZO-HEXOXIZID and BZO-CHMOXIZID underwent similar metabolism to those reported in the literature, via the metabolic pathways of N-dealkylation, hydroxylation, ketone formation and oxidative defluorination (to alcohol or carboxylic acid). The results suggest that OXIZIDs are mainly metabolized at the N-alkyl moiety and the major metabolic pathways are hydroxylation when the N-alkyl moiety is a simple hydrocarbon, whereas functional-group-specific pathways (dihydrodiol formation and oxidative defluorination) are preferred when the moiety contains specific functional groups (alkene or fluoro), as has been observed for other synthetic cannabinoids. The major metabolites generated via these major metabolic pathways should serve as useful analytical targets for urine analysis. Furthermore, the higher abundance of glucuronidated metabolite suggests that enzymatic hydrolysis of glucuronides may be necessary for urine analysis to increase phase I metabolite concentration and improve detection.

Abstract The adsorption structure and photocatalytic decomposition of nerve agent, O-ethyl S-[2-diisopropylaminoethyl] methylphosphonothionate (VX) on powdery TiO2 film experimentally studied by using in-situ attenuated total reflection - infrared Fourier transform spectroscopy (ATR-FTIR) at ambient condition. Characteristic IR frequency of VX molecules adsorbed at the surface of TiO2 was observed. The results showed that VX molecule at the surface of TiO2 was immediately oxidized to ethyl methylphosphonic acid (EMPA) and diisopropylaminoethanthiol (DESH) by the P-S cleavage. C-N cleavage by the photocatalysis was also observed simultaneously with appearance of the characteristic IR frequencies as secondary amin species. The oxidation of an aliphatic function group of VX molecule was then accompanied by the decomposition of the skeletal structure as P-S and C-N of VX. Rarely EA2192 production by the TiO2 photocatalysis has experimentally verified by this ATR-FTIR analysis. The plausible adsorption structure and the photocatalytic reaction mechanism of VX at the surface of the TiO2 photocatalyst are also elucidated.

Automotive glasses are important forensic evidence often recovered from crime scenes. Black ceramic prints on automotive glasses contains various elements in high concentrations. A portable X-ray fluorescence spectrometer (pXRF) allows an instant and nondestructive analysis of various elements. In this study, the Bruker Tracer 5 g was used as the pXRF equipment. The NIST SRM612 glass standard was used to determine the limit of detection (LODs) of a pXRF and its optimal conditions. The acceleration voltages of 15, 30, and 50 kV were appropriate for measuring Si K-alpha (1.740 keV)-Ni K-alpha (7.473 keV), Cu K-alpha (8.042 keV)-Pb L-alpha (10.552 keV), and after Bi K-alpha (10.839 keV), respectively. The pXRF was used to compare 37 black ceramic prints on automotive glasses from the known source. The samples were divided into two groups: the Pb type and the Bi type. The samples were compared in pairs. The most appropriate and effective indicators for discriminating between the Pb and Bi type of black ceramic prints on automotive glasses were Zr K-alpha/Pb L-alpha and Cu K-alpha/Cr K-alpha for the Pb type, and Zr K-alpha/Bi L-alpha and Cu K-alpha/Cr-alpha for the Bi type, respectively. The samples were compared with other elements detected by pXRF to further discriminate them. 98.9% of all pairs were successfully discriminated. Results showed that black ceramic prints on automotive glasses are able to be discriminated by pXRF.

Gel permeation chromatography (GPC)/size exclusion chromatography was developed for the forensic discrimination of polyester fibers. Fibers were dissolved with 1,1,1,3,3,3-hexafluoro-2-propanol and chloroform, and applied to liquid chromatography (LC) using tandemly coupled two styrene-divinylbenzene co-polymer GPC columns, chloroform mobile phase, 254 nm light absorbance monitoring, and using the polystyrene standards as molecular weight (MW) calibration reference compounds. Polyester polymers were eluted as the main tailing peaks followed by small low-MW peaks that included cyclic ethylene terephthalate trimer, which was assigned by LC-mass spectrometry and Fourier transform infrared spectroscopy. Fibers were discriminated using the GPC parameters of weight average MW (Mw), Mw/number average MW (polydispersity index, PDI), and percentage peak area of low-MW peak (PPAL). Reproducible GPC was achieved through controlled injection amount (3-16 mu g fiber). Inter-sample coefficient of variance (CV) in Mw, PDI, and PPAL for one poly(ethylene terephthalate) (PET) fiber was measured as 0.01, 0.02 and 0.016, respectively, and used as configurated CV for the discrimination between fiber pairs. The normalized variances for Mw, PDI, and PPAL were summed, and the square root was calculated. A value exceeding 2 indicated significant discrimination in the three-dimensional 2 s criteria. A comparison of 37 PET fibers (Microtrace Forensic Fiber Reference Collection, commercial polyester shirts, in-house manufactured PET yarns) was executed for GPC. Only 5.1% of the combinations could not be discriminated between the two different fibers. Site differences in the commercial PET shirts were found, where fibers taken from the neck sites were significantly different from those of the chest and sleeve.