Springer Science and Business Media LLC

SIMS depth profiling experiments have been used to elucidate the layered structure, the impurity distribution, and current induced changes in polymeric light emitting diodes (LEDs). In the first investigated system (ITO/PPV/Al), a poly-p-phenylene-vinylene (PPV) layer has been deposited onto an indium/tin oxide (ITO) glass support, and covered by an aluminium top electrode. A well defined aluminium oxide interlayer has been found in between the polymer and the Al overlayer. Furthermore, an enrichment of chlorine has been detected at both electrode-polymer interfaces, a residue from the polymer preparation process. This observation points to a chemical reaction between the electrodes and elimination products that are liberated during the thermal decomposition of the polymer precursor. In the second system, three different polymeric layers have been spin-coated onto an ITO substrate, i.e. a pure poly-methylphenylsilane (PMPS) layer, a second PMPS layer doped with an organic dye, and finally a polystyrene (PS) layer containing an oxadiazole derivative. By the addition of a bromine containing label into the first layer, it can be shown that the two PMPS layers have been diffusing into each other, whereas the PMPS and the PS regions have remained well separated. As found with the single layer devices, the formation of an interfacial oxide layer between the PS layer and the Al top electrode has been observed. Investigations of driven multilayer LEDs have provided evidence for drastic current-induced degradation effects.

The detection and interpretation of gunshot residues (GSR) plays an important role in the investigation of firearm-related events. Commonly, the analysis focuses on inorganic particles incorporating elements derived from the primer. However, recent changes in ammunition formulations and possibility that particles from non-firearm sources can be indistinguishable from certain primer particles challenge the standard operational protocol and call for adjustments, namely the combination of inorganic and organic GSR analysis. Two protocols for the combined collection and subsequent analysis of inorganic and organic GSR were developed and optimised for 15 compounds potentially present in organic GSR (OGSR). These protocols were conceptualised to enable OGSR analysis by ultrahigh-performance liquid chromatography (UHPLC) coupled with UV detection and triple quadrupole tandem mass spectrometry (confirmation) and IGSR analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). Using liquid extraction, the extraction recoveries from spiked swabs and stubs were ~80 % (50–98 % for swabs, 64–98 % for stubs). When the mixed OGSR standard was applied to the hands and recovered in the way that is usual for IGSR collection, GSR stubs performed significantly better than swabs (~30 %) for the collection of OGSR. The optimised protocols were tested and compared for combined OGSR and inorganic GSR analysis using samples taken at a shooting range. The most suitable protocol for combined collection and analysis of IGSR and OGSR involved collection using GSR stubs followed by SEM-EDX analysis and liquid extraction using acetone followed by analysis with UHPLC.

A real-time automated process control tool for coffee roasting is presented to consistently and accurately achieve a targeted roast degree. It is based on the online monitoring of volatile organic compounds (VOC) in the off-gas of a drum roaster by proton transfer reaction time-of-flight mass spectrometry at a high time (1 Hz) and mass resolution (5,500 m/Δm at full width at half-maximum) and high sensitivity (better than parts per billion by volume). Forty-two roasting experiments were performed with the drum roaster being operated either on a low, medium or high hot-air inlet temperature (= energy input) and the coffee (Arabica from Antigua, Guatemala) being roasted to low, medium or dark roast degrees. A principal component analysis (PCA) discriminated, for each one of the three hot-air inlet temperatures, the roast degree with a resolution of better than ±1 Colorette. The 3D space of the three first principal components was defined based on 23 mass spectral profiles of VOCs and their roast degree at the end point of roasting. This provided a very detailed picture of the evolution of the roasting process and allowed establishment of a predictive model that projects the online-monitored VOC profile of the roaster off-gas in real time onto the PCA space defined by the calibration process and, ultimately, to control the coffee roasting process so as to achieve a target roast degree and a consistent roasting.

Mass spectrometry (MS)–based analysis of complex biological samples is essential for biomedical research and clinical diagnostics. The separation prior to MS plays a key role in the overall analysis, with separations having larger peak capacities often leading to more identified species and improved confidence in those identifications. High-resolution ion mobility (IM) separations enabled by Structures for Lossless Ion Manipulation (SLIM) can provide extremely rapid, high-resolution separations and are well suited as a second dimension of separation following nanoscale liquid chromatography (nanoLC). However, existing sample handling approaches for offline coupling of separation modes require microliter-fraction volumes and are thus not well suited for analysis of trace biological samples. We have developed a novel nanowell-mediated fractionation system that enables nanoLC-separated samples to be efficiently preconcentrated and directly infused at nanoelectrospray flow rates for downstream analysis. When coupled with SLIM IM-MS, the platform enables rapid and high-peak-capacity multidimensional separations of small biological samples. In this study, peptides eluting from a 100 nL/min nanoLC separation were fractionated into ~ 60 nanowells on a microfluidic glass chip using an in-house–developed robotic system. The dried samples on the chip were individually reconstituted and ionized by nanoelectrospray for SLIM IM-MS analysis. Using model peptides for characterization of the nanowell platform, we found that at least 80% of the peptide components of the fractionated samples were recovered from the nanowells, providing up to ~tenfold preconcentration for SLIM IM-MS analysis. The combined LC-SLIM IM separation peak capacities exceeded 3600 with a measurement throughput that is similar to current one-dimensional (1D) LC-MS proteomic analyses.