Pressure-Sensitive Adhesive Combined with Paper Spray Mass Spectrometry for Low-Cost Collection and Analysis of Drug Residues

Illicit drug use causes over half a million deaths worldwide every year. Drugs of abuse are commonly smuggled through customs and border checkpoints and, increasingly, through parcel delivery services. Improved methods for detection of trace drug residues from surfaces are needed. Such methods should be robust, fieldable, sensitive, and capable of detecting a wide range of drugs. In this work, commercially produced paper with a pressure-sensitive adhesive coating was utilized for the collection and analysis of trace drug residues by paper spray mass spectrometry (MS). This modified substrate was used to combine sample collection of drug residues from surfaces with rapid detection using a single paper spray ticket. The all-in-one ticket was used to probe different surfaces commonly encountered in forensic work including clothing, cardboard, glass, concrete, asphalt, and aluminum. A total of 10 drugs (acetyl fentanyl, fentanyl, clonazolam, cocaine, heroin, ketamine, methamphetamine, methylone, U-47700, and XLR-11) were evaluated and found to be detectable in the picogram range using a benchtop mass spectrometer and in the low nanogram range using a portable ion trap MS. The novel approach demonstrates a simple yet effective sampling strategy, allowing for rapid identification from difficult surfaces via paper spray mass spectrometry.

Discovery of treatment for nerve agents targeting a new metabolic pathway

The inhibition of acetylcholinesterase is regarded as the primary toxic mechanism of action for chemical warfare agents. Recently, there have been numerous reports suggesting that metabolic processes could significantly contribute to toxicity. As such, we applied a multi-omics pipeline to generate a detailed cascade of molecular events temporally occurring in guinea pigs exposed to VX. Proteomic and metabolomic profiling resulted in the identification of several enzymes and metabolic precursors involved in glycolysis and the TCA cycle. All lines of experimental evidence indicated that there was a blockade of the TCA cycle at isocitrate dehydrogenase 2, which converts isocitrate to α-ketoglutarate. Using a primary beating cardiomyocyte cell model, we were able to determine that the supplementation of α-ketoglutarate subsequently rescued cells from the acute effects of VX poisoning. This study highlights the broad impacts that VX has and how understanding these mechanisms could result in new therapeutics such as α-ketoglutarate.

Proteomic and Metabolomic Profiling Identify Plasma Biomarkers for Exposure to Ultra-low Levels of Carfentanil

Despite the recent epidemic of fentanyl abuse, there are few validated assays capable of rapidly detecting these compounds. In order to improve the ability to detect carfentanil at physiologically relevant concentrations, we developed a systems biology approach to discover host-based markers which are specifically amplified upon exposure in a rabbit model. For this work, two "omics" pipelines utilizing mass spectrometry were developed and leveraged. First, a proteomics pipeline was developed to interrogate the blood plasma for protein-based biomarkers. Due to the incredible dynamic range of the plasma protein content, a multi-dimensional fractionation technique was used to partition and more accurately investigate the circulating plasma proteome. Isobaric tandem mass tags were integrated into the workflow to make quantitative assessments across all animals for an extended time course post-exposure. In addition to the proteomics efforts, blood plasma was also processed through an untargeted metabolomics pipeline. This approach allows for the identification of >800 small molecule features. By processing and analyzing data sets in parallel, we were able to identify a unique fingerprint of protein and metabolite perturbations that manifest following exposure to carfentanil.

On-substrate derivatization for detection of highly volatile G-series chemical warfare agents via paper spray mass spectrometry

RATIONALE

The analysis of chemical warfare agents (CWAs) from ambient atmosphere presents an analytical challenge due to their ease of degradation and volatility. Herein is described a method for derivatizing CWAs directly onto a paper spray substrate prior to analysis. This derivatization allows for much longer times of analysis without sample degradation and with little to no sample preparation.

METHODS

Derivatization was performed using 2-[(dimethylamino)methyl] phenol both in-vial and directly on paper spray cartridges. Solution studies were carried out over time and samples were analyzed via liquid chromatography/tandem mass spectrometry (LC/MS/MS) operated in positive ion mode. Paper spray substrates impregnated with the derivatizing agent prior to CWA vapor capture were also analyzed over time using a mass spectrometer operated in positive ion mode.

RESULTS

Use of 2-[(dimethylamino)methyl] phenol as a paper spray substrate dopant enables derivatization of G-series compounds into lower volatility complexes. The reaction occurs in solution and in the vapor phase. This new technique effectively traps and captures G-series agents for analysis while extending the time for which the compound remains absorbed. The complex is highly suitable for direct analysis via paper spray mass spectrometry.

CONCLUSIONS

Derivatization of paper spray substrates was shown to greatly increase the time for analysis of CWAs. This technique, combined with the vapor phase capture stage outlined previously, allows for rapid, quantitative CWA detection by paper spray ionization with little or no sample preparation.

On-substrate Enzymatic Reaction to Determine Acetylcholinesterase Activity in Whole Blood by Paper Spray Mass Spectrometry

Currently, all assays measuring acetylcholinesterase (AChE) activity following a suspected nerve agent exposure leverage methodologies that fail to identify the agent. This limits the overall effectiveness and ability to administer proper countermeasures. As such, there is an urgent need to identify novel, rapid, and more comprehensive approaches to establish AChE activity, including identification of the toxicant. Paper spray mass spectrometry was used to monitor the activity of acetylcholinesterase, both in-solution and on modified hydrophobic paper surface. Hydrophobic paper surfaces were prepared using vaporized trichloro(3,3,3-trifluoropropyl)silane. In both approaches, mixtures of diluted human whole blood with and without VX were mixed with a non-endogenous AChE specific substrate, 1,1-dimethyl-4-acetylthiomethylpiperidinium (MATP+). Formation of the cleaved MATP+ product was monitored over time and compared to MATP+ to determine relative AChE activity. This on-substrate assay was effective at determining AChE activity and identifying the toxicant; however, determination of AChE activity in-solution proceeded at a slower rate. The on-substrate assay serves as a pioneering example of an enzymatic reaction occurring on the surface of a paper spray ionization ticket. This work broadens the range of applications relating to paper spray ionization-based clinical diagnostic assays. Graphical Abstract ᅟ.

Metal-Organic Framework Modified Glass Substrate for Analysis of Highly Volatile Chemical Warfare Agents by Paper Spray Mass Spectrometry

Paper spray mass spectrometry has been shown to successfully analyze chemical warfare agent (CWA) simulants. However, due to the volatility differences between the simulants and real G-series (i.e., sarin, soman) CWAs, analysis from an untreated paper substrate proved difficult. To extend the analytical lifetime of these G-agents, metal-organic frameworks (MOFs) were successfully integrated onto the paper spray substrates to increase adsorption and desorption. In this study, several MOFs and nanoparticles were tested to extend the analytical lifetimes of sarin, soman, and cyclosarin on paper spray substrates. It was found that the addition of either UiO-66 or HKUST-1 to the paper substrate increased the analytical lifetime of the G-agents from less than 5 min detectability to at least 50 min.

Genetic and biochemical studies of phosphatase activity of PhoR

In Escherichia coli, PhoR is the histidine kinase of the phosphate regulon. It has been postulated that PhoR may function as a phospho-PhoB phosphatase. Experiments with four precise phoR deletion mutants supported this hypothesis and suggested that this activity resides within the histidine phosphorylation domain. This biochemical activity was confirmed by using a separately expressed histidine phosphorylation domain.