Screening for Forensically Relevant Drugs Using Data-Independent High-Resolution Mass Spectrometry.

Forensic and clinical laboratories are expected to provide a rapid screening of samples for a wide range of analytes; however, the ever-changing landscape of illicit substances makes analysis complicated. There is a great need for untargeted methods that can aid these laboratories in broad-scope drug screening. Liquid chromatography hyphenated with high-resolution mass spectrometry (LC-HRMS) has become a popular technique for untargeted screening and presumptive identification of drugs of abuse due to its superior sensitivity and detection capabilities in complex matrices. An untargeted extraction and data acquisition method was evaluated for the broad screening of high-priority drugs of abuse in whole blood. A total of 35 forensically relevant target analytes were identified and extracted at biologically relevant low and high (10× low) concentrations from whole blood using supported liquid extraction. Data-independent acquisition was accomplished using ultraperformance liquid chromatography and a quadrupole time-of-flight mass spectrometry. Results were acceptable for screening assays, with limits of detection at or below the recommended low-concentration cutoffs for most analytes. Analyte ionization varied from 30.1 to 267.6% (average: 110.5%) at low concentrations and from 8.6 to 383.5% (average: 93.6%) at high concentrations. Extraction recovery ranged from 8.5 to 330.5% (average: 105.3%) at low concentrations and from 9.4 to 127.5% (average: 82.7%) at high concentrations. This variability was also captured as precision, ranging from 4.7 to 135.2% (average: 36.5%) at low concentrations and from 0.9 to 59.0% (average: 21.7%) at high concentrations. The method described in this work is efficient and effective for qualitative forensic toxicology screening, as demonstrated by analysis of 166 authentic suspected impaired driver and postmortem specimens. That said, it is critical that laboratories establishing untargeted LC-HRMS screening assays be aware of the strengths and limitations across diverse drug categories and chemical structures.

Pharmacology of R-(-)-Methamphetamine in Humans: A Systematic Review of the Literature.

Methamphetamine exists as two stereoisomers: S-(+)-methamphetamine ((+)-MAMP) and R-(-)-methamphetamine ((-)-MAMP). The (+)-MAMP stereoisomer is a well-known central nervous system stimulant, available as a pharmaceutical and clandestine drug of abuse. However, the (-)-MAMP stereoisomer is less well understood despite commercial availability for over 30 years as an over-the-counter (OTC) nasal decongestant in the Vicks Vapor Inhaler (a product of Procter & Gamble). Recently, several generic versions have become available, decreasing the cost and increasing the availability of (-)-MAMP-containing nasal sprays to consumers. Despite widespread commercial availability and use in the United States, a paucity of literature exists on the pharmacology of (-)-MAMP in humans. This knowledge gap is problematic, given the difficulty in separating (-)-MAMP and (+)-MAMP isomers in laboratory assays for workplace drug testing, suspected impaired drivers, post-mortem investigations, and assessment of drug involvement in crimes. In response, this systematic review of the literature coalesces and summarizes available knowledge of (-)-MAMP pharmacology in humans. It was found that available knowledge relies heavily on urine drug and metabolite concentrations, systematic pharmacokinetics studies are lacking, and existing knowledge has been derived from a total of 99 unique participants. The impacts of highlighted gaps in the literature are discussed, focusing on forensic toxicology and law enforcement, and future research directions are suggested.

Monitoring the Activation of Open Metal Sites in [FexM3-x(µ3-O)] Cluster-Based Metal-Organic Frameworks by Single-Crystal X-ray Diffraction.

While trinuclear [FexM3-x(µ3-O)] cluster-based metal-organic frameworks (MOFs) have found wide applications in gas storage and catalysis, it is still challenging to identify the structure of open metal sites obtained through proper activations and understand their influence on the adsorption and catalytic properties. Herein, we use in situ variable-temperature single-crystal X-ray diffraction to monitor the structural evolution of [FexM3-x(µ3-O)]-based MOFs (PCN-250, M = Ni2+, Co2+, Zn2+, Mg2+) upon thermal activation and provide the snapshots of metal sites at different temperatures. The exposure of open Fe3+ sites was observed along with the transformation of Fe3+ coordination geometries from octahedron to square pyramid. Furthermore, the effect of divalent metals in heterometallic PCN-250 was studied for the purpose of reducing the activation temperature and increasing the number of open metal sites. The metal site structures were corroborated by X-ray absorption and infrared spectroscopy. These results will not only guide the pretreatment of [FexM3-x(µ3-O)]-based MOFs but also corroborate spectral and computational studies on these materials.

Comparison of Breath- and Blood-Alcohol Concentrations in a Controlled Drinking Study.

In this work, 114 volunteers were dosed with 80-proof liquor to produce peak blood-alcohol concentration (BAC) or breath-alcohol concentration (BrAC) of 0.040-0.080 g/100 mL blood or g/210 L breath. This was followed by a 30 minute deprivation period before simultaneous blood and breath samples were collected and the alcohol concentration quantified. BAC was determined by gas chromatography with flame ionization detection and BrAC by a dual-sensor Intox EC/IR II instrument. Paired Student t-tests showed that differences between paired blood- and breath-alcohol results differed significantly. Results from these two measurement methods are highly correlated and, on average, measured BAC was 11.3% greater than BrAC. There were 10 instances of BrAC being greater than the corresponding BAC, and the average difference between these two values was 0.0059 g/100 mL. Agreement plots of coupled BAC and BrAC revealed a mean bias of 0.00754 g/100 mL and 95% limits of agreement (LOA) at -0.00705 and 0.0221 g/100 mL. Once BrAC values were truncated to the hundredths place as required by Wisconsin state statute, only three participants had greater BrAC than corresponding BAC, with an average difference between these values of 0.008 g/100 mL. Agreement plots with truncated BrAC values gave a mean bias of 0.0120 g/100 mL and 95% LOA at -0.00344 and 0.0275 g/100 mL. Data showed that typically, blood samples had greater alcohol concentrations than corresponding breath values. Differences were exacerbated by Wisconsin's statutory requirement that reported breath alcohol measurements be truncated to the hundredths place, whereas blood has no corresponding mandate.

Estimating Uncertainty in Wisconsin's Evidential Breath Alcohol Measurements.

Breath alcohol measurement accuracy and precision quantification is a critical component of impaired driving prosecution and is required for laboratory accreditation. The Chemical Testing Section of Wisconsin's Department of Transportation conducted a bottom-up study to quantify uncertainty of breath alcohol measurements conducted on Intoximeter's EC/IR II instrument. After an exercise in combined uncertainty source identification, individual input values were either reported from National Institute of Standards and Technology traceable reference materials or quantified using instrument data from 2014 to 2018. From input values, an expanded uncertainty value of 4.58 × 10-3 g/210L was found that encompasses all identified sources with a 95% confidence interval.

Erratum: High performance platinum single atom electrocatalyst for oxygen reduction reaction.

This corrects the article DOI: 10.1038/ncomms15938.

High performance platinum single atom electrocatalyst for oxygen reduction reaction.

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

Amorphous boron nanorod as an anode material for lithium-ion batteries at room temperature.

We report an amorphous boron nanorod anode material for lithium-ion batteries prepared through smelting non-toxic boron oxide in liquid lithium. Boron in theory can provide capacity as high as 3099 mA h g-1 by alloying with Li to form B4Li5. However, experimental studies of the boron anode have been rarely reported for room temperature lithium-ion batteries. Among the reported studies the electrochemical activity and cycling performance of the bulk crystalline boron anode material are poor at room temperature. In this work, we utilized an amorphous nanostructured one-dimensional (1D) boron material aiming at improving the electrochemical reactivity between boron and lithium ions at room temperature. The amorphous boron nanorod anode exhibited, at room temperature, a reversible capacity of 170 mA h g-1 at a current rate of 10 mA g-1 between 0.01 and 2 V. The anode also demonstrated good rate capability and cycling stability. The lithium storage mechanism was investigated by both sweep voltammetry measurements and galvanostatic intermittent titration techniques (GITTs). The sweep voltammetric analysis suggested that the contributions from lithium ion diffusion into boron and the capacitive process to the overall lithium charge storage are 57% and 43%, respectively. The results from GITT indicated that the discharge capacity at higher potentials (>∼0.2 V vs. Li/Li+) could be ascribed to a capacitive process and at lower potentials (<∼0.2 V vs. Li/Li+) to diffusion-controlled alloying reactions. Solid state nuclear magnetic resonance (NMR) measurement further confirmed that the capacity is from electrochemical reactions between lithium ions and the amorphous boron nanorod. This work provides new insights into designing nanostructured boron materials for lithium-ion batteries.

High-performance oxygen reduction catalysts in both alkaline and acidic fuel cells based on pre-treating carbon material and iron precursor.

We demonstrate a new and simple method for pre-treating the carbon material and iron precursor to prepare oxygen reduction reaction (ORR) catalysts, which can produce super-high performance and stability in alkaline solution, with high performance in acid solution. This strategy using cheap materials is simply controllable. Moreover, it has achieved smaller uniform nanoparticles to exhibit high stability, and the synergetic effect of Fe and N offered much higher performance in ORR than commercial Pt/C, with high maximum power density in alkaline and acid fuel cell test. So it can make this kind of catalysts be the most promising alternatives of Pt-based catalysts with best performance/price.

Direct synthesis of bimetallic Pd3Ag nanoalloys from bulk Pd3Ag alloy.

We report a transformative, all inorganic synthesis method of preparing supported bimetallic Pd(3)Ag alloy nanoparticles. The method involves breaking down bulk Pd(3)Ag alloy into the nanoparticles in liquid lithium, converting metallic Li to LiOH, and transferring Pd(3)Ag nanoparticles/LiOH mixture onto non-water-soluble supports, followed by leaching off the LiOH with water under ambient conditions. The size of the resulting Pd(3)Ag nanoparticles was found narrowly distributed around 2.3 nm characterized by transmission electron microscope (TEM). In addition, studies by X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) spectroscopy, and X-ray absorption near edge structure (XANES) spectroscopy showed that the resulting Pd(3)Ag nanoparticles inherited similar atomic ratio and alloy structure as the starting material. The synthesized Pd(3)Ag nanoparticles exhibited excellent catalytic activity toward hydrogenation of acrolein to propanal.