Direct soil analysis by paper spray mass spectrometry: Detection of drugs and chemical warfare agent hydrolysis products

Chromogenic Detection of the Organophosphorus Nerve Agent Simulant DCP Mediated by Rhodium(II,II) Paddlewheel Complexes

Organophosphorus nerve agents (OPNAs) pose a great threat to humanity. Possessing extreme toxicity, rapid lethality, and an unassuming appearance, these chemical warfare agents must be quickly and selectively identified so that treatment can be administered to those affected. Chromogenic detection is the most convenient form of OPNA detection, but current methods suffer from false positives. Here, nitrogenous base adducts of dirhodium(II,II) acetate were synthesized and used as chromogenic detectors of diethyl chlorophosphate (DCP), an OPNA simulant. UV-vis spectrophotometry was used to evaluate the sensitivity and selectivity of the complexes in the detection of DCP. Visual limits of detection (LOD) for DCP were as low as 1.5 mM DCP, while UV-vis-based LODs were as low as 0.113 μM. The dirhodium(II,II) complexes were also tested with several potential interferents, none of which produced a visual color change that could be mistaken for OPNA response. Ultimately, the Rh2(OAc)4(1,8-diazabicyclo[5.4.0]undec-7-ene)2 complex showed the best combination of detection capability and interferent resistance. These results, when taken together, show that dirhodium(II,II) paddlewheel complexes with nitrogenous base adducts can produce instant, selective, and sensitive detection of DCP. It is our aim to further explore and apply this new motif to produce even more capable OPNA sensors.

Ambient ionisation mass spectrometry for drug and toxin analysis: A review of the recent literature

Ambient ionisation mass spectrometry (AIMS) is a form of mass spectrometry whereby analyte ionisation occurs outside of a vacuum source under ambient conditions. This enables the direct analysis of samples in their native state, with little or no sample preparation and without chromatographic separation. The removal of these steps facilitates a much faster analytical process, enabling the direct analysis of samples within minutes if not seconds. Consequently, AIMS has gained rapid popularity across a diverse range of applications, in particular the analysis of drugs and toxins. Numerous fields rely upon mass spectrometry for the detection and identification of drugs, including clinical diagnostics, forensic chemistry, and food safety. However, all of these fields are hindered by the time-consuming and laboratory-confined nature of traditional techniques. As such, the potential for AIMS to resolve these challenges has resulted in a growing interest in ambient ionisation for drug and toxin analysis. Since the early 2000s, forensic science, diagnostic testing, anti-doping, pharmaceuticals, environmental analysis and food safety have all seen a marked increase in AIMS applications, foreshadowing a new future for drug testing. In this review, some of the most promising AIMS techniques for drug analysis will be discussed, alongside different applications of AIMS published over a 5-year period, to provide a summary of the recent research activity for ambient ionisation for drug and toxin analysis.

Green Assessment of Analytical Procedures for the Determination of Pharmaceuticals in Sewage Sludge and Soil

The main difficulties when analyzing pharmaceutically active compounds (PhACs) in solid environmental samples is the complexity of the samples and the low concentration levels of such pollutants. Most efforts are focused in achieving good analytical performance parameters such as high recoveries or low detection limits without considering if the methods are environmentally friendly. In this work, the main tools proposed for assessing the greenness of analytical methodologies (Analytical Eco-scale, Green Analytical Procedure Index (GAPI), and Analytical GREEnness metric (AGREE)) have been applied to nine analytical procedures that include recent important analytical tendencies. The three metrics identified the paper spray ionization method as the greenest procedure since it used untreated samples for direct mass spectrometry analysis. Using Analytical Eco-scale, most of the evaluated procedures were rated as "acceptable green". However, the use of internal standards resulted key in the environmental impact of the method which provided contradictory results versus other metrics. GAPI found greenness similarities between most of selected methods, hindering a greenness classification. AGREE allowed the weighting of each evaluation criterion providing a greenness ranking. The application of each metric detecting their weaknesses and strengths was discussed. The incorporation of validation analytical features in greenness metrics was a gap revealed.

Ultra-low current electrospray ionization of chloroform solution for the analysis of perfluorinated sulfonic acids

RATIONALE

Femtoamp and picoamp electrospray ionization (ESI) characteristics of a nonpolar solvent were explored. The direct ESI mass spectrometry analysis of chloroform extract solution enabled rapid analysis of perfluorinated sulfonic acid analytes in drinking water.

METHODS

Neat chloroform solvent and extracts were directly used in a typical wire-in ESI setup using micrometer emitter tips. Ionization currents were measured with femtoamp sensitivity while ramping the spray voltage from 0 to -5000 V. Methanol was used as a comparison to illustrate the characteristics of electrospraying chloroform. The effects of spray voltage and inlet temperature were studied. A liquid-liquid extraction workflow was developed to analyze perfluorooctanoate sulfonate (PFOS) in drinking water using an ion-trap mass spectrometer.

RESULTS

The ionization onset of chloroform solution was 41 ± 17 fA at 300 V. The ionization current gradually increased with voltage while remaining below 100 pA when using voltages up to -5000 V. The ion signal of PFOS was significantly enhanced to improve the limit of detection (LoD) to 25 ppt in chloroform. Coupled with a liquid-liquid extraction workflow, LoD of 0.38-5.1 ppt and a quantitation range of 5-400 ppt were achieved for perfluorinated sulfonic compounds in 1-ml water samples.

CONCLUSIONS

Femtoamp and picoamp modes expand the solvent compatibility range of ESI and can enable quantitative analysis in parts per trillion (ppt) concentrations.

PAMAM-Functionalized Paper as a New Substrate for the Paper Spray Mass Spectrometry Measurement of Proteins

Paper surface functionalization with polyamidoamine (PAMAM) dendrimers has been developed for increased sensitivity analysis of proteins by paper spray mass spectrometry (PS-MS). PAMAM is a branched polymeric compound with an ethylenediamine core linked to repeating PAMAM units that generates an outer surface rich in primary amines. These positively charged amine groups can interact electrostatically with negatively charged residues (e.g., aspartate, glutamate) on the protein surface. PAMAM inner amide moieties can also promote hydrogen bonding with protein surface oxygens, making PAMAM a useful material for protein extraction. PAMAM-functionalized PS-MS paper strips were used to extract proteins from biofluids, dipped in acetonitrile to remove unbound constituents, dried, and then measured with PS-MS. The use of this strategy was optimized and compared with unmodified paper strips. PAMAM-functionalized paper substrates provided sixfold greater sensitivity for albumin, 11-fold for hemoglobin, sevenfold for insulin, and twofold for lysozyme. The analytical performance of the functionalized paper substrate was evaluated through the analysis of albumin in urine, achieving linearity with R² > 0.99, LOD of 1.1 μg mL^-1, LOQ of 3.8 μg mL^-1, precision better than 10%, and relative recovery 70-83%. The method was applied to quantify urinary albumin from nine anonymous patient samples (concentrations ranged from 6.5 to 77.4 μg mL^-1), illustrating its potential for the diagnosis of microalbuminuria. These data demonstrate the utility of paper modification with the PAMAM dendrimer for sensitive PS-MS analysis of proteins, opening a path for further applications in clinical diagnosis through the analysis of disease-related proteins.

Toxic effects and bioaccumulation of pinacolyl methylphosphonate acid in zebrafish following soman exposure to a water environment

Soman has been shown to be highly neurotoxic and can be easily degraded to produce pinacolyl methylphosphonate acid (PMPA). Thus, the perniciousness of PMPA deserved serious attention after soman was exposed to the environment. However, the toxicity of PMPA was not clearly elucidated to date. In this regard, the objective of this study was to determine if PMPA could pose an environmental risk after soman exposure to a water environment. In this study, the toxicity and bioaccumulation assessments of PMPA were carried out on zebrafish. Histological examination was used to assess the toxicity of PMPA in zebrafish and revealed that PMPA has chronic toxicity in view of tissue injury. The contents of PMPA in whole zebrafish and tissues were determined after soman exposure. The result showed that PMPA bioaccumulated in the whole zebrafish and tissue, especially the liver and intestinal tissues. This is the first report showing that the hydrolyzate of a G-series chemical nerve agent could accumulate in organisms. This study offers novel insights into the environmental risk assessments associated with soman exposure to a water environment.

Potential of desorption electrospray ionization and paper spray ionization with high-resolution mass spectrometry for the screening of sports doping agents in urine

In this work, desorption electrospray ionization and paper spray ionization both with high-resolution mass spectrometry (DESI-HRMS and PSI-HRMS) were explored for the fast and direct analysis of stimulants and diuretics in urine samples. The analysis was performed at a resolution of 70 000 FWHM (m/z 200) using a quadrupole-Orbitrap mass spectrometer in full scan acquisition mode, detecting stimulants and diuretics in positive and negative ion modes, respectively. The most critical parameters affecting the desorption and ionization efficiencies of compounds were optimized, paying particular attention to the optimization of the spray solvent for PSI-HRMS analysis and to the selection of the DESI sample substrate. For stimulants, the PSI-HRMS method performed better than DESI-HRMS, allowing the direct analysis of raw urine samples with better signal-to-noise ratios than DESI. However, results obtained for diuretics were not as satisfactory as we expected. The PSI-HRMS method was applied to the screening of 52 stimulants for doping control purposes, providing satisfactory detectability for most of them at the Minimum Reporting Level (MRL) in less than 2 minutes for each single analysis. Despite the advantages offered by the PSI-HRMS method, in this study is also included a discussion on the limitations observed because of the presence of interference for some compounds.

Rapid Screening and Quantitation of Drugs of Abuse by Both Positive and Negative Modes via Coated Blade Spray-Mass Spectrometry

Solid-phase microextraction (SPME)-direct mass spectrometry (MS) has proven to be an efficient tool for the rapid screening and quantitation of target compounds at trace levels. However, it is challenging to perform screening using both positive and negative modes in one analytical run without compromising scanning speed and detection sensitivity. To take advantage of the special geometry of a coated blade spray (CBS) blade, which consists of two flat sides coated with the same SPME coating, we developed a CBS-MS method that enables desorption and ionization to be performed in positive ionization mode on one side of a coated blade and negative ionization mode on the other side of the same blade. By simply flipping the blade 180°, MS analysis in both ionization modes on different sides can be completed in 40 s. Combining this approach with an automated Concept 96-blade-based SPME system allowed analysis for one sample in positive and negative modes to be completed in less than 1 min. The workflow was optimized by using a biocompatible polyacrylonitrile as an undercoating layer and a binder of polyacrylonitrile/hydrophilic-lipophilic balance (HLB) particles, which enabled the rapid analysis of 20 drugs of abuse in saliva samples in both positive and negative modes. The proposed method provided low limits of quantification (between 0.005 and 10 ng/mL), with calibration linear correlation coefficients ⩾ 0.9925, accuracy between 72% and 126%, and relative precision < 15% for three validation points.

Insects as Chemical Sensors: Detection of Chemical Warfare Agent Simulants and Hydrolysis Products in the Blow Fly Using LC-MS/MS

In this work, blow flies were investigated as environmental chemical sample collectors following a chemical warfare attack (CWA). Blow flies sample the environment as they search for water and food sources and can be trapped from kilometers away using baited traps. Three species of blow flies were exposed to CWA simulants to determine the persistence and detectability of these compounds under varying environmental conditions. A liquid chromatography mass spectrometry (LC-MS/MS) method was developed to detect CWA simulants and hydrolysis products from fly guts. Flies were exposed to the CWA simulants dimethyl methylphosphonate and diethyl phosphoramidate as well as the pesticide dichlorvos, followed by treatment-dependent temperature and humidity conditions. Flies were sacrificed at intervals within a 14 day postexposure period. Fly guts were extracted and analyzed with the LC-MS/MS method. The amount of CWA simulant in fly guts decreased with time following exposure but were detectable 14 days following exposure, giving a long window of detectability. In addition to the analysis of CWA simulants, isopropyl methylphosphonic acid, the hydrolysis product of sarin, was also detected in blow flies 14 days post exposure. This work demonstrates the potential to obtain valuable samples from remote or access-restricted areas without risking lives.

Rapid, in situ detection of chemical warfare agent simulants and hydrolysis products in bulk soils by low-cost 3D-printed cone spray ionization mass spectrometry

Chemical warfare agents (CWAs) are toxic chemicals that have been used as disabling or lethal weapons in war, terrorist attacks, and assasinations. The Chemical Weapons Convention (CWC) has prohibited the use, development, production, and stockpiling of CWAs since its initiation in 1997, however, the threat of deployment still looms. Detection of trace CWAs post-deployment or post-remediation, in bulk matrices such as soil, often requires lengthy sample preparation steps or extensive chromatographic separation times. 3D-printed cone spray ionization (3D-PCSI), an ambient ionization mass spectrometric (MS) technique, provides a rapid, simple, and low-cost method for trace CWA analysis in soil matrices for both in-laboratory and in-field detection. Described here is the utilization of conductive 3D-printed cones to perform both rapid sampling and ionization for CWA simulants and hydrolysis products in eight solid matrices. The analysis of trace quantities of CWA simulants and hydrolysis products by 3D-PCSI-MS coupled to both a commercial benchtop system and a field-portable MS system is detailed. Empirical limits of detection (LOD) for CWA simulants on the benchtop MS ranged from 100 ppt to 750 ppb and were highly dependant on solid matrix composition, with the portable system yielding similar spectral data from alike matrices, albeit with lower sensitivity.

Electric field-assisted multiphase extraction to increase selectivity and sensitivity in liquid chromatography-mass spectrometry and paper spray mass spectrometry

In this work, for the first time, chromatographic paper was used for a multiphase extraction assisted by an electric field (MPEF) and directly coupled to paper spray mass spectrometry (PS-MS). Using this approach, five tricyclic antidepressants (TCAs) were determined in oral fluid. Firstly, the MPEF conditions were optimized using liquid chromatography-mass spectrometry (LC-MS/MS). The effects of the chromatographic paper and the types of electrolyte used in the acceptor phase, the organic solvent type and the amount used in the donor phase, the extraction time, and the applied electric potential were all investigated. After optimization, the analytes were extracted from the donor solution (sample and acetonitrile 1:1 (v/v)) over a period of 10 min at 300 V, crossing the free liquid membrane (1-octanol) and reaching the acceptor phase (chromatographic paper wetted with 400 mmol L^-1 acetic acid). The method using LC-MS/MS was validated, demonstrating a linear range from 2 to 12 ng mL^-1, with detection and quantification limits of 0.13-0.25 and 0.44-0.84 ng mL^-1, respectively, an intraday precision of less than 20%, and no matrix effect observed. The optimized MPEF conditions were then applied to determine TCAs by PS-MS and for this analysis cyclobenzaprine was used as an internal standard. The easy, fast and direct approach of coupling MPEF with PS-MS analysis, as well as the pre-concentration and the low standard deviation of replicates (less than 20%), demonstrates that this method can be useful for screening in clinical and toxicological analysis.

Paperspray Ionization Mass Spectrometry as a Tool for Predicting Real-Time Optimized Dosing of the Chemotherapeutic Drug Melphalan

BACKGROUND

Melphalan, an important component of hematopoietic stem cell transplantation (HSCT) preparative regimens, is associated with significant toxicity and large between patient variability in pharmacokinetics making it difficult to calculate the optimal dose for pediatric patients. Paperspray (PS) ionization generates gas phase analyte ions directly from a dried blood spot without the need for prior sample preparation or chromatography. With these advantages, a validated PS-MS/MS assay was developed and applied to the 'real-time' determination of melphalan pharmacokinetics (PK).

METHODS

Melphalan was quantified by stable-labeled isotope dilution analysis in whole blood by PS-MS/MS. Blood samples were obtained at timed intervals from patients during HSCT after administration of a very low (test) dose of melphalan to avoid toxicity. Pharmacokinetics parameters were calculated using WinNonlin v.6.4. From these data, the optimal therapeutic dose was estimated and full dose PK repeated.

RESULTS

PS-MS/MS method was linear over a large dynamic range (25-50 000 ng/mL), intra- and interassay reproducibility of quality control samples was <15% CV. With essentially no prior sample preparation, PS-MS/MS measurement of blood melphalan concentrations showed excellent correlation (R2 = 0.959, n = 62) with a validated electrospray-LC-MS/MS method. Trapezoidal area under the curves calculated for 5 patients administered low dose melphalan showed a high linear correlation (R2 = 0.981) between the PS-MS/MS and LC-MS/MS methods. The faster PS approach permitted real-time PK evaluation of individual patients.

CONCLUSIONS

A validated PS-MS/MS assay for melphalan in patients undergoing HSCT is described that facilitates pharmacokinetic-guided individualized precision dosing with immediate bedside dose adjustments to improve outcomes by balancing toxicity and efficacy of melphalan.

Sample preparation and instrumental methods for illicit drugs in environmental and biological samples: A review

Detection of illicit drugs in the environmental samples has been challenged as the consumption increases globally. Current review examines the recent developments and applications of sample preparation techniques for illicit drugs in solid, liquid, and gas samples. For solid samples, traditional sample preparation methods such as liquid-phase extraction, solid-phase extraction, and the ones with external energy including microwave-assisted, ultrasonic-assisted, and pressurized liquid extraction were commonly used. The sample preparation methods mainly applied for liquid samples were microextraction techniques including solid-phase microextraction, microextraction by packed sorbent, dispersive solid-phase extraction, dispersive liquid-liquid microextraction, hollow fiber-based liquid-phase microextraction, and so on. Capillary microextraction of volatiles and airborne particulate sampling were primarily utilized to extract illicit drugs from gas samples. Besides, the paper introduced recently developed instrumental techniques applied to detect illicit drugs. Liquid chromatograph mass spectrometry and gas chromatograph mass spectrometry were the most widely used methods for illicit drugs samples. In addition, the development of ambient mass spectrometry techniques, such as desorption electrospray ionization mass spectrometry and paper spray mass spectrometry, created potential for rapid in-situ analysis.

The current role of mass spectrometry in forensics and future prospects

Mass spectrometry (MS) techniques are highly prevalent in crime laboratories, particularly those coupled to chromatographic separations like gas chromatography (GC) and liquid chromatography (LC). These methods are considered "gold standard" analytical techniques for forensic analysis and have been extensively validated for producing prosecutorial evidentiary data. However, factors such as growing evidence backlogs and problematic evidence types (e.g., novel psychoactive substance (NPS) classes) have exposed limitations of these stalwart techniques. This critical review serves to delineate the current role of MS methods across the broad sub-disciplines of forensic science, providing insight on how governmental steering committees guide their implementation. Novel, developing techniques that seek to broaden applicability and enhance performance will also be highlighted, from unique modifications to traditional hyphenated MS methods to the newer "ambient" MS techniques that show promise for forensic analysis, but need further validation before incorporation into routine forensic workflows. This review also expounds on how recent improvements to MS instrumental design, scan modes, and data processing could cause a paradigm shift in how the future forensic practitioner collects and processes target evidence.

2D MS/MS Spectra Recorded in the Time Domain Using Repetitive Frequency Sweeps in Linear Quadrupole Ion Traps

Ion trap mass spectrometers have emerged as powerful on-site analytical platforms, in spite of limited mass resolution, due to their compatibility with ambient ionization methods and ready implementation of tandem mass spectrometry (MS/MS). When operated at constant trapping voltage, ions can be activated at their secular frequencies and all MS/MS experiments can be performed, including the two-dimensional tandem mass scan (2D MS/MS scan) in which all precursor ions and their subsequent product ions are both identified and correlated. In the new method of performing this 2D MS/MS experiment presented here, the precursor ions are excited by a nonlinear (inverse Mathieu q) frequency sweep while the resulting product ions are identified by their ejection time within a repeating orthogonally applied nonlinear (inverse Mathieu q) frequency sweep. This resulting compact representation contains the total fragmentation behavior of a collection of ionized compounds and captures detailed chemical information efficiently (typically in 1 s). The approach is implemented using a simple single mass analyzer instrument. This methodology was tested on three different multicomponent mixtures: drugs of abuse, peptides, and fentanyl analogs. The data are compared with those obtained by more common MS/MS scan methods.

Paper-based sorptive phases for microextraction and sensing

The simplification of the analytical procedures, including cost-effective materials and detectors, is a current research trend. In this context, paper has been identified as a useful material thanks to its low price and high availability in different compositions (office, filter, chromatographic). Its porosity, flexibility, and planar geometry permit the design of flow-through devices compatible with most instrumental techniques. This article provides a general overview of the potential of paper, as substrate, on the simplification of analytical chemistry methodologies. The design of paper-based sorptive phases is considered in-depth, and the different functionalization strategies are described. Considering our experience in sample preparation, special attention has been paid to the use of these phases under the classical microextraction-analysis workflow, which usually includes a chromatographic separation of the analytes before their determination. However, the interest of these materials extends beyond this field as they can be easily implemented into spectroscopic and electrochemical sensors. Finally, the direct analysis of paper substrates in mass spectrometry, in the so-called paper-spray technique is also discussed. This review is more focused on presenting ideas rather than the description of specific applications to draw a general picture of the potential of these materials.