Finally, the approach is tested on street samples from forensic seizures. Overall, this system allows for the on-site identification of ketamine by law enforcement agents in an easy-to-use and rapid manner on cargos and seizures, thereby disrupting the distribution channel and avoiding the illicit drug reaching the end-user.Mass spectrometry imaging (MSI) is an established analytical tool capable of defining and understanding complex tissues by determining the spatial distribution of biological molecules. Three-dimensional (3D) cell culture models mimic the pathophysiological environment of in vivo tumors and are rapidly emerging as a valuable research tool. Here, multimodal MSI techniques were employed to characterize a novel aggregated 3D lung adenocarcinoma model, developed by the group to mimic the in vivo tissue. Regions of tumor heterogeneity and the hypoxic microenvironment were observed based on the spatial distribution of a variety of endogenous molecules. Desorption electrospray ionization (DESI)-MSI defined regions of a hypoxic core and a proliferative outer layer from metabolite distribution.  https://www.selleckchem.com/products/r-hts-3.html  Targeted metabolites (e.g., lactate, glutamine, and citrate) were mapped to pathways of glycolysis and the TCA cycle demonstrating tumor metabolic behavior. The first application of imaging mass cytometry (IMC) with 3D cell culture enabled single-cell phenotyping at 1 μm spatial resolution. Protein markers of proliferation (Ki-67) and hypoxia (glucose transporter 1) defined metabolic signaling in the aggregoid model, which complemented the metabolite data. Laser ablation inductively coupled plasma (LA-ICP)-MSI analysis localized endogenous elements including magnesium and copper, further differentiating the hypoxia gradient and validating the protein expression. Obtaining a large amount of molecular information on a complementary nature enabled an in-depth understanding of the biological processes within the novel tumor model. Combining powerful imaging techniques to characterize the aggregated 3D culture highlighted a future methodology with potential applications in cancer research and drug development.Unlabeled and deuterium-labeled dimeric lignin model compounds with β-O-4 linkages were evaporated and ionized using negative ion mode electrospray ionization, transferred into a linear quadrupole ion trap, isolated, and subjected to collision-activated dissociation (CAD; MS2 experiments). The elemental compositions of the fragment ions were determined by using a high-resolution Orbitrap mass analyzer, and their structures were examined using further CAD experiments (MS n experiments wherein n = 2-5). Data analysis was facilitated by determining the fragmentation pathways for several deprotonated model compounds. The structures of the key fragment ions of several pathways were determined by comparison of the CAD mass spectra measured for undeuterated and deuterated analogues and for deprotonated authentic compounds. Some of the proposed reaction mechanisms were tested by examining additional deprotonated synthetic model compounds. Quantum chemical calculations were used to delineate the most likely reaction pathways and reaction mechanisms. This work provides basic information needed for the design of tandem mass spectrometry-based CAD sequencing strategies for mixtures of lignin degradation products.A method for the detection and quantification of nanoplastics (NPTs) at environmentally relevant concentrations was developed. It is based on conjugating nanoplastics with functionalized metal (Au)-containing nanoparticles (NPs), thus making them detectable by highly sensitive inductively coupled plasma mass spectrometry (ICP-MS) operated in single particle (SP) mode. The selectivity of the method was achieved by the coupling of negatively charged carboxylate groups present at the surface of nanoplastics with a positively charged gelatin attached to the custom-synthesized AuNPs. The adsorbed Au produced a SP-ICP-MS signal allowing the counting of individual nanoplastic particles, and hence their accurate quantification ( less then 5% error). Polystyrene (PS) particle models with controlled surface functionalization mimicking the nanoplastics formed during natural degradation of plastic debris were used for the method development. The nanoplastic number concentration quantification limit was calculated at 8.4 × 105 NPTs L-1 and the calibration graph was linear up to 3.5 × 108 NPTs L-1. The method was applied to the analysis of nanoplastics of up to 1 μm in drinking, tap, and river water. The minimum detectable and quantifiable size depended on the degree of functionalization and the surface available for labeling. For a fully functionalized nanoplastic, the lower size detectable by this strategy is reported as 135 nm. In this study, authors use the recommendation for the definition of nanoplastics as plastic particles with sizes ranging between 1 nm and 1 μm, although it has not been accepted by a dedicated organization.Enzyme-linked immunosorbent assays (ELISA) for the detection of soluble epoxide hydrolase (sEH), a key enzyme in the metabolism of fatty acids and a biomarker, may increasingly represent an important diagnostic tool. However, there is a lack of ELISAs for mouse sEH quantification, thus resulting in a bottleneck in understanding the pathogenesis of many diseases related to sEH based on mouse models. In this work, nanobodies recognizing mouse sEH were obtained through rebiopanning against mouse sEH in the previous phage display library of human sEH. Later, we developed four ELISAs involving a combination of anti-mouse sEH polyclonal antibodies (pAbs) and nanobodies. It was found that the double antibodies worked as dual filters and had a huge impact on both the sensitivity and selectivity of sandwich immunoassays. The switch from anti-human sEH pAbs to anti-mouse sEH pAbs led to over a 100-fold increase in the sensitivity and a dramatic decrease of the limit of detection to a picogram per milliliter range in format B (pAb/biotin-VHH/streptavidin-poly-horseradish peroxidase). Moreover, we found that the four sandwich ELISAs might demonstrate excellent selectivities to mouse sEH, despite the antibodies alone showing significant cross-reactivity to the matrix, indicating the enhanced selectivity of double antibodies as dual filters. Eventually, for the first time, the ELISA (format B) was successfully used to measure the mouse sEH level in cancer cells with ultralow abundances. The ELISAs proposed here represent a sensitive tool for tracking sEH in various biological processes and also provide deep insights into developing sandwich immunoassays against various targets in terms of both the sensitivity and selectivity.