Screening and Quantification of Aliphatic Primary Alkyl Corrosion Inhibitor Amines in Water Samples by Paper Spray Mass Spectrometry

Direct analysis and identification of long chain aliphatic primary diamine Duomeen O (n-oleyl-1,3-diaminopropane), corrosion inhibitor in raw water samples taken from a large medium pressure water tube boiler plant water samples at low LODs (<0.1 pg) has been demonstrated for the first time, without any sample preparation using paper spray mass spectrometry (PS-MS). The presence of Duomeen O in water samples was confirmed via tandem mass spectrometry using collision-induced dissociation and supported by exact mass measurement and reactive paper spray experiments using an LTQ Orbitrap Exactive instrument. Data shown herein indicate that paper spray ambient ionization can be readily used as a rapid and robust method for in situ direct analysis of polymanine corrosion inhibitors in an industrial water boiler plant and other related samples in the water treatment industry. This approach was applied for the analysis of three complex water samples including feedwater, condensate water, and boiler water, all collected from large medium pressure (MP) water tube boiler plants, known to be dosed with varying amounts of polyamine and amine corrosion inhibitor components. Polyamine chemistry is widely used for example in large high pressure (HP) boilers operating in municipal waste and recycling facilities to prevent corrosion of metals. The samples used in this study are from such a facility in Coventry waste treatment facility, U.K., which has 3 × 40 tonne/hour boilers operating at 17.5 bar

Polymerization-based signal amplification for paper-based immunoassays

Diagnostic tests in resource-limited settings require technologies that are affordable and easy to use with minimal infrastructure. Colorimetric detection methods that produce results that are readable by eye, without reliance on specialized and expensive equipment, have great utility in these settings. We report a colorimetric method that integrates a paper-based immunoassay with a rapid, visible-light-induced polymerization to provide high visual contrast between a positive and a negative result. Using Plasmodium falciparum histidine-rich protein 2 as an example, we demonstrate that this method allows visual detection of proteins in complex matrices such as human serum and provides quantitative information regarding analyte levels when combined with cellphone-based imaging. It also allows the user to decouple the capture of analyte from signal amplification and visualization steps.Bill & Melinda Gates Foundation (Award 51308)United States. Defense Advanced Research Projects Agency (HR0011-12-2-0010)National Science Foundation (U.S.). Graduate Research FellowshipBurroughs Wellcome Fund (Career Award at the Scientific Interface

Dried Blood Spheroids for Dry-State Room Temperature Stabilization of Microliter Blood Samples

It is well-known that 2D dried blood spots on paper offer a facile sample collection, storage, and transportation of blood. However, large volume requirements, possible analyte instability, and difficult sample recovery plague this method, lowering confidence in analyte quantification. For the first time, we demonstrate a new approach using 3D dried blood spheroids for stabilization of small volume blood samples, mitigating these effects without cold storage. Blood spheroids form on hydrophobic paper, preventing interaction between the sample and paper substrate, eliminating all chromatographic effects. Stability of the enzyme alanine transaminase and labile organic compounds such as cocaine and diazepam were also shown to increase in the spheroid by providing a critical radius of insulation. On-surface analysis of the dried blood spheroids using paper spray mass spectrometry resulted in sub-ng/mL limits of detection for all illicit drugs tested, representing 1 order of magnitude improvement compared with analysis from 2D dried blood spots

Ion generation, ion collection and ionic reactions outside the mass spectrometer

Traditionally, the formation, deposition and reactions of molecular ions are conducted in high vacuum environment, or at least, at reduced pressure. In this thesis, molecular ions are considered as ordinary organic molecules and they are generated, transmitted and reacted with vapors or adsorbates on surfaces, all in the ordinary open environment. For example, ion soft landing was successfully implemented under ambient conditions. In ambient ion soft landing, ions generated by electrospray ionization are passed pneumatically through a heated metal drying tube, their polarity is selected using ion deflectors, and the dry selected ions are deposited onto a selected surface at a specified location. Unlike the corresponding vacuum soft-landing experiment, where ions are mass-selected and soft-landed within a mass spectrometer, here the ions to be soft-landed are selected through the choice of a compound that gives predominantly one ionic species upon ambient ionization. No mass analysis is performed during the soft landing experiment. The purified ions were typically used for surface preparation and modification. However, when utilized as reagents for organic reactions (e.g., pyrylium cation conversion into pyridinium cation) in a solvent-free environment, the ionic species provided a regioselective route to the expected reaction product when employing bifunctional reagents (e.g., D-lysine and ethanolamine) compared with the corresponding bulk solution-phase reaction conditions. Charged microdroplets associated with incompletely dried ions could also be selected for surface reactions by choice of the temperature of the drying tube inserted between the ion source and the electrical ion deflectors. This reaction condition allowed at least one order of magnitude increase in reaction rate compared with the bulk solution phase reaction conducted using the same quantities of starting reagents. The droplet reaction condition was further developed in three different ways: (i) nanoelectrospray emitter array, (ii) contained-electrospray apparatus and (iii) electrospray synthetic apparatus with high efficient product collection system. These are envisioned to impact the field of synthetic chemistry at larger scales due to the dramatic reaction rate enhancements. Several reaction systems have been studied under the charged microdroplet condition including [3,3]-sigmatropic rearrangement (e.g., Borsche-Drecsel cyclization), C-N (e.g., Girard condensation) and C-C (e.g., Claisen-Schmidt condensation) bonds formation. The droplet reaction was extended to thin film reactions which represent an alternative version of limited-volume reactors. The aza-Michael addition and the Mannich condensation were observed to occur in thin films deposited on ambient surfaces. Fundamentals of ion generation in the ambient environment were also studied, particularly the mechanism of desorption electrospray ionization (DESI). Critical evidence based on studies of surfactants and non-aqueous solvents has been provided for the proposed DESI (droplet pick-up) mechanism

Assessment of creatinine concentration in whole blood spheroids using paper spray ionization–tandem mass spectrometry

AbstractAccurate quantification of blood creatinine is important to estimate the glomerular filtration rate. Existing techniques using liquid chromatography tandem mass spectrometry (LC–MS/MS) have a high accuracy and eliminate most interferences encountered in routine enzymatic and Jaffé methods. However, they require laborious and time-consuming sample treatment and data acquisition. The aim of this study is to develop a fast and simple method to enable a direct analysis of whole blood creatinine with performance measures that are comparable to conventional LC–MS/MS. 5μL whole blood is formed as a three-dimensional spheroid on hydrophobic silanized paper substrates which then undergoes paper-spray ionization—tandem mass spectrometry (PSI–MS/MS). The method is validated using real human samples and compared with LC–MS/MS. PSI–MS/MS whole blood analysis exhibited a lower limit of quantification of 2.5 μg/mL, precision ≤ 6.3%, recovery in the range of 88–94% and excellent linearity (R2 &gt; 0.99; 2.5—20 μg/mL) covering the normal range for creatinine levels. Creatinine levels were comparable to those measured by LC–MS/MS with small deviations of less than 0.3 μg/mL. This simple, fast and accurate microsampling technique for direct analysis of creatinine from whole blood shows promise for routine clinical screening and monitoring. This approach can be readily extended for other analytes of interest and, due to inherent advantages relating to cost, storability, speed, and simplicity, it can be especially advantageous for use in resource-limited settings.</jats:p

Mass Spectrometry for Paper-Based Immunoassays: Toward On‑Demand Diagnosis

Current analytical methods, either point-of-care or centralized detection, are not able to meet recent demands of patient-friendly testing and increased reliability of results. Here, we describe a two-point separation on-demand diagnostic strategy based on a paper-based mass spectrometry immuno­assay platform that adopts stable and cleavable ionic probes as mass reporter; these probes make possible sensitive, interruptible, storable, and restorable on-demand detection. In addition, a new touch paper spray method was developed for on-chip, sensitive, and cost-effective analyte detection. This concept is successfully demonstrated via (i) the detection of <i>Plasmodium falciparum</i> histidine-rich protein 2 antigen and (ii) multiplexed and simultaneous detection of cancer antigen 125 and carcinoembryonic antigen

Reactive Charged Droplets for Reduction of Matrix Effects in Electrospray Ionization Mass Spectrometry

A new quantitative contained-electrospray (ES) process is described here that employs a movable ES emitter to control the reactivity of charged microdroplets by varying their exposure time with acid vapor. The method allows elimination of ion suppression effects caused by the presence of various surface active compounds that coelute with the analyte. For mixtures, contained-ESI mass spectrometric analysis produces relative ion intensities that reflect the true concentrations of analytes in solution. The mechanism for this effect has been elucidated and ascribed to the generation of fine initial droplets in the presence of a high abundance of protons; together, these two factors eliminate competition for charge and space during ion formation. Examples of analytes tested include steroids, phospholipids, phosphopeptides, and sialylated glycans. At least 1 order of magnitude improvement in detection limits, sensitivity, and accuracy of detection was observed when compared to conventional electrospray

Charge inversion under plasma-nanodroplet reaction conditions excludes Fischer esterification for unsaturated fatty acids: a chemical approach for type II isobaric overlap

The fusion of nonthermal plasma with charged nanodroplets enables selective esterification of saturated fatty acids, which is utilized to overcome challenges associated with type II isobaric overlap in direct infusion mass spectrometry.</jats:p

Determining Surface Energy of Porous Substrates by Spray Ionization

We have developed a new spray-based method for characterizing surface energies of planar, porous substrates. Distinct spray modes (electrospray versus electrostatic-spray), from the porous substrates, occur in the presence of an applied DC potential after wetting with solvents of different surface tension. The ion current resulting from the spray process maximizes when the surface energy of the porous substrate approaches the surface tension of the wetting solvent. By monitoring selected ion current (e.g., benzoylecgonine, m/z 290→168) with a mass spectrometer or total ion current with an ammeter, the solvent surface tension yielding the maximum ion current was determined to indicate the surface energy of the solid. Detailed evaluations using polymeric substrates of known surface energies enabled effective calibration of the approach that resulted in the correct estimation of the surface energy of hydrophobic paper substrates prepared by gas-phase silanization. A three-parameter empirical model suggests that the experimentally observed ion current profile is governed by differential partitioning of analyte controlled by the interfacial forces between the wetting solvent and the porous substrate.This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Langmuir, copyright © American Chemical Society after peer review. To access the final edited and published work see 10.1021/acs.langmuir.9b02419. Posted with permission.</p