When explosives are encountered on the battlefield, the use of portable GC–MS is valuable for the detection and confirmatory identification of pre- and post-detonation threats. In addition, this technique provides information about the source of explosives based on the detection and identification of trace-level chemicals in the sample. The data presented here confirm this capability.
Size-exclusion chromatography (SEC), with the use of ammonium acetate buffer, can be coupled on-line to electrospray ionization MS for the characterization of size variants of therapeutic monoclonal antibodies (mAbs). A quadrupole time-of-flight (QTOF) MS system was employed, and the MS method was optimized to achieve favorable sensitivity for high-mass detection, while maintaining the structural integrity of the aggregates (or high molecular weight species) and fragments (or low molecular weight species).
Food quality differences are dependent on botanical and geographical origins of primary food ingredients as well as storage and handling. Quality assessment for food materials, including cocoa and olive oil, is demonstrated by applying two-dimensional gas chromatography (GC×GC) combined with time-of-flight mass spectrometry (TOF-MS) and pattern recognition.
Drug discovery using high-throughput screening of discreet compounds, and the discovery of natural products with pharmacological mechanisms of action, rely on bioassay-guided fractionation analysis. Recent applications of affinity selection–mass spectrometry (AS-MS) are useful for exploring the discovery of ligands to membrane-bound proteins and RNA targets.
Per- and polyfluoroalkyl substances (PFAS) are found in firefighting foams and consumer products. They are ubiquitous in the environment and are an emerging human health concern. This work compares the 2009 and 2018 revised US Environmental Protection Agency (EPA) LC–MS/MS methods of analysis for PFAS in drinking water.
In the human food supply, public confidence is affected by contaminants and misreporting of nutritional information. This article highlights three events that required development of new mass spectrometry methods, including the detection of pesticides (such as fipronil and glyphosate), and the detection and quantification of fat-soluble vitamins.
In late-stage pharmaceutical development a new generation of high-resolution mass spectrometers and ion mobility mass spectrometers operate as orthogonal separation techniques and have greatly increased the ability to resolve impurities and increase the level of analytical information gained from a single analysis.
In this study, atmospheric pressure photoionization (APPI) is compared to the default ionization method, electrospray ionization (ESI), for solution-phase samples. These mass spectrometry methods are compared and optimized relative to artificial wastewater for the detection and quantitation of pharmaceuticals frequently found as environmental contaminants.
An arsenic speciation method using LA–ICP-MS was developed to provide a more accurate procedure for the determination of arsenic species in marine oils. It was validated for the analysis of five arsenic species in krill oil, and should also prove useful when quantitating inorganic arsenic species in other marine oils.
Method setup and optimization steps are explored to illustrate how an ICP-MS/MS method can be defined and tested to ensure consistent performance. Users can benefit from improved interference removal performance without the complex method development inherent in the use of ion-molecule reaction chemistry
A simple analytical method, requiring no sample pretreatment, was developed for determination of chromium, iron, nickel, and zinc in mouthwash by inductively coupled plasma‒optical emission spectrometry (ICP-OES). This method allowed the study of potential migration by iron, chromium, and nickel from stainless steel containers.
Our annual review of products introduced at Pittcon or during the previous year
Complex isobaric and polyatomic spectral interferences can be mitigated using triple quadrupole ICP-MS (ICP-MS/MS) with a collision–reaction cell (CRC). This configuration allows for the multielement characterization and detection of smaller nanoparticle sizes.
The structural complexity of monoclonal antibodies (mAbs) challenges the capabilities of even the most advanced chromatography and mass spectrometry techniques. This study examines the use of micro-pillar array columns in combination with mass spectrometry for peptide mapping of both mAbs and antibody–drug conjugates (ADCs).
Under a suitable thermal oxidation regime, vegetable oils yield a mixture of volatile and semivolatile organics that exhibit very high antimicrobial activities against a variety of microbial species. Volatile and semivolatile products were characterized with GC–MS using electron ionization and chemical ionization. The thermal oxidation of vegetable oils resulted in the formation of an array of shortand medium-chain acids, aldehydes, and ketones that act synergistically to yield a potent antimicrobial disinfectant.
Since glycans are responsible for bioactivity, solubility, immunogenicity, and clearance rate from circulation, it is vital to have a detailed map of glycans in therapeutic glycoproteins. Detailed glycoprotein structural analysis must be able to identify the peptide sequence where the glycans are attached as well as the structure of the glycan portion, including oligosaccharide sequence and glycosyl linkages. This article details methods for mass spectrometry experiments on both released glycans (“glycomics”), as well as on intact glycopeptides (“glycoproteomics”) using electron transfer dissociation, high-energy collision dissociation, and collisioninduced dissociation fragmentation pathways, which are needed to fully elucidate the structure of glycoproteins.
In this study, general extract screening of food storage materials was done with nontargeted analytical methods to understand what analytes could potentially leach into food or beverages. GC and mass spectral deconvolution effectively separated analytes within the complex mixture and TOF-MS provided full mass range spectral data for identification. This workflow can be used for confident characterization of components present as extractables from food packaging materials.
There is growing interest in the determination of endogenous proteins in biological samples for diagnostic purposes, because a concentration increase or decrease of such proteins can allows us to monitor the state of a pathological condition such as cancer. Immunocapture LC–MS/MS analysis combines the workflow of conventional immunological assays with LC–MS analysis. This article describes typical challenges, such as cross reactivity and the mass spectrometer’s dynamic range, as well as the advantages of isoform differentiation and multiplexing.
Interest in connecting ion mobility spectrometry (IMS) to GC and especially to LC is now growing. One favorable property of IMS is that it can work with ambient pressure and can be easily connected to a gas or liquid chromatograph. Analytical applications of GC–MS and LC–MS are very different and encompass investigations into food, medical science, environment, drugs of abuse, chemical warfare agents, and explosives.
In drug development, quantitative determination of a candidate drug and its metabolites in biofluids is an important step. The standard technique for quantitative metabolite profiling is radiolabeling followed by HPLC with radiodetection, but there are disadvantages to this approach, including cost and time, as well as safety and ethical concerns related to administering radiolabeled compounds to humans. Frank Vanhaecke and his research group at Ghent University have been developing an alternative technique, and he recently spoke to us about this work.
We present a brief review of this year’s ASMS conference, which took place June 4–8 in Indianapolis, Indiana.
Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Mass spectrometry is chirally blind, and so cannot directly distinguish the two enantiomers of chiral molecules. Here we discuss how enantiomers may be differentiated by Mass Spectrometry correlated with PhotoElectron Circular Dichroism (MS-PECD) using an electron–ion coincidence imaging spectrometer. Following an ionizing circular polarized laser pulse, ions and electrons are detected in coincidence on their respective time- and position sensitive detectors. The MS-PECD asymmetry measured on electrons tagged by the mass of their corresponding parent ion directly reveals that the compound with identified mass is chiral without the need for any prior enantiomeric separation or enantiomer-selective complexation. MS-PECD enables direct enantiomeric excess measurement of multi-component chiral samples in a table-top mass spectrometer.
Our annual review of new spectroscopy products introduced at Pittcon, or during the previous year.
A simple method for extraction and concentration of trace organic compounds found in water for gas chromatography-mass spectrometry (GC-MS) analysis was developed. The method used 25 and 45 mL glass vials with a 5-10 µm thick polymer coatings for extraction of analytes from 20 and 40 mL water samples, respectively. Analytes were subsequently transferred from the polymer coating into an organic solvent, which was reduced in volume to 200-400 µL for analysis. A 10-20 µL sample from the vial was transferred to a tiny coiled stainless steel wire filament using a micro-syringe, or by dipping the coil into the sample. After air evaporation of the solvent, the coil was inserted into the heated injection port of a portable GC-MS system where the analytes were desorbed. Injection using the coiled wire filament eliminated sample discrimination of high boiling point compounds, and minimized system contamination caused by sample matrix residues. The GC-MS contained a new resistively heated column bundle that allowed elution of low-volatility compounds in less than 4 min. Analyses of organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyl congeners, pyrethroid insecticides, phthalate esters, and n-alkanes in water and wastewater samples were accomplished for low ppb concentrations in less than 10 min total analysis time.
