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Method Translation in Gas ChromatographyThe advantages of using software to optimize GC methods with practical examples for pesticide analysis are described.
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Nanometer Internal Diameter Fused Silica Capillary TubingScientists employ fused silica capillary tubing routinely in a wide range of analytical applications, encompassing GC, CE, capillary LC, and CEC. It has proven as an ideal substrate for interfacing in hyphenated techniques.
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Control of Matrix Effects in Bioanalytical MS–MS Using On-line Multidimensional Solid-Phase ExtractionThe authors discuss a solid-phase extraction (SPE) clean-up procedure for drugs present in biofluids.
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Volatile Organic Compounds in Wastewater: Performance of US EPA Method 624 on Modern GC–MS and Purge and Trap InstrumentationUS EPA wastewater method 624 Purgeables was originally published as 40 CFR Part 136 Appendix A in the mid 1980s.
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Accelerated Discovery and Quantitation of Lipids in Complex ExtractsThe authors discuss analytical methods for lipidomics.
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Quantifying an Anthrax LF Inhibitor in Human Plasma by HPLC-MS-MSThis article describes the method development and performance characteristics of the validated LFI assay and evaluates stability in human plasma.
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Mass Analysis from Kilodaltons to Megadaltons Using Macroion Mobility SpectrometryMass spectrometry (MS) has advanced to analyze ever-larger biomolecules with the invention of soft ionization techniques like electrospray ionization (ESI). Although ESI has provided a method of generating ions of high mass, mass spectrometers generally suffer both lower sensitivity and lower resolution as the mass-to-charge ratio of an ion increases. To extend the mass range of ionized macromolecules beyond the limits of MS, macroion mobility spectrometry utilizes ion mobility sizing to characterize charge-reduced ESI-generated macroions from >5 kDa to beyond megadalton masses. One prominent application of macroion mobility spectrometry, highlighted here, is the high sensitivity analysis of intact proteins, antibodies, and conjugates in which molecular masses range from antibody light-chain fragments to high mass immunoglobulin multimers.
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Quantifying an Anthrax LF Inhibitor in Human Plasma by HPLC-MS-MSThis article describes the method development and performance characteristics of the validated LFI assay and evaluates stability in human plasma.
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Using pH-LC to Control Selectivity of Acidic and Basic Compounds on Gemini-NXThe use of mobile phase pH to control analyte ionization states (pH-LCâ„¢) in reversed phase HPLC separations is a highly effective way to change selectivity. The ionized species of an analyte is shown to have higher polarity (less hydrophobicity) than the neutral species, which results in a loss of expected retention for that analyte. This can be attributed to less interaction with the hydrophobic stationary phase and greater affinity with the aqueous portion of the mobile phase. Ionized species also participate in ionic interactions with exposed and activated silanols, which impact peak shape and reproducibility.
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Towards Merging Targeted and Untargeted Analysis of the Lipidome, Metabolome, and ExposomeTomas Cajka previews his keynote lecture at HPLC 2019, where he will introduce an LC−MS workflow (LIpids, Metabolites and eXposome compounds [LIMeX]) for simultaneous extraction of complex lipids, polar metabolites, and exposome compounds that combines LC–MS targeted and untargeted analysis.
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Understanding the Behaviour of Pharmaceutical PolymersThis article discusses GPC and gives examples of the use of the technique in excipient analysis.
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Separation Science: The State of the Art: Multidimensional Gas Chromatography Moves ForwardIn this extended special feature to celebrate the 35th anniversary edition of LCGC Europe, key opinion leaders from the separation science community explore contemporary trends in separation science and identify possible future developments.
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Evaluation of Modified QuEChERS for Pesticide Analysis in CannabisWhile systems for growing, production and sale of cannabis and cannabis related products are well established, regulation and enforcement of quality and safety testing have lagged behind. However, state governments and private labs are focusing on product safety testing with special emphasis on pesticide analysis. This is partially the result of various product recalls, media attention and concern from patient advocacy groups. We evaluated a modified QuEChERS LC-MS/MS method for analysis of multiresidue pesticides. The AOAC QuEChERS method was used for a reduced 1.5 g amount of plant material and processed with a universal dSPE formulation. LC-MS/MS analysis used constant polarity switching ESI and monitored at least two transitions per analyte. Matrix-matched calibration was used for quantitation and both method and instrument internal standards were used. Analyte recovery validation was performed according to FDA guidelines by testing three matrices at three fortification levels in triplicate for over 200 pesticides. For the large majority of pesticides, in all three matrices and at all three fortification levels, recovery was between 70-120%.
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Simultaneous Quantitation of 2- and 4-Methylimidazole in Carbonated DrinksThe chemicals 2- and 4-methylimidazole (2-MI and 4-MI) are by-products produced during the manufacturing of caramel coloring ingredients used to darken food products such as carbonated beverages and soy sauce.
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Microemulsion HPLCMicroemulsion-based HPLC (MELC) is a recent development offering reduced sample preparation times for complex samples and generic separation conditions applicable to a wide range of solutes. This article introduces the concepts of MELC and discusses the possible benefits and future applications.
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Advances in TOF-MS-Based Screening for Food Safety Residue Analysis with a Positive ApproachMass spectrometry plays an increasingly significant role in the analysis of residues and contaminants in food. Here we will illustrate how the combination of ultrahigh-pressure liquid chromatography (UHPLC) and high-resolution time-of-flight-mass spectrometry (TOF-MS) is used to generate a screen of veterinary drug residues in products of animal origin. The use of UHPLC–TOF-MS and dedicated, workflow directed software allows rapid screening for large numbers of residues and automated quantification of positive samples. In addition, we illustrate how the data generated using MSE acquisition mode enable critical structural information to be collected, which offers additional selectivity and confirmatory data for compound identification and facilitates elucidation of the structure of newly discovered compounds.
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Interaction of Dichloromethane Solvent with n-Alkylamines Analyzed by Electron Ionization GC–MSThe analysis of amines by gas chromatograph ;mass spectrometry (GC–MS) using electron ionization (EI) has always been a challenge
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Optimization of Sample Preparation for Pesticide Analysis in Oil-Based Cannabis Products Using LipiFiltr®This application note outlines the performance benefits achieved with UCT’s LipiFiltr® cleanup cartridge for the analysis of pesticides in oil-based cannabis products using LC–MS/MS analysis.
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“Truly Natural”: Fully Automated Stir-Bar Sorptive Extraction with Enantioselective GC–MS Quantitation of Chiral Markers of Peach AromaA simple, automated, and fast method to quantify complex odorants in foods is described using stir-bar sorptive extraction (SBSE) combined with fast enantioselective GC–MS analysis. The total analytical method takes only 30 minutes and does not require any sample pretreatment.
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Increasing Productivity of ADME Studies Using Accurate Mass TechnologyA new time-of-flight mass spectrometer was evaluated for performing simultaneous metabolic stability measurement and metabolite identification with ultrahigh-pressure liquid chromatography. Six representative compounds (clomipramine, diclofenac, imipramine, haloperidol, verapamil, and midazolam) were incubated in rat liver microsomes at a more physiologically relevant substrate concentration (1 ?M). High-resolution full-scan and product-ion spectra were acquired in a single injection using generic methodology. Quantitative clearance of the parent was measured using the full-scan data. Major metabolites were identified using the accurate mass product ion spectra. High scanning speed allowed for a sufficient number of data points to be collected across the chromatographic peak for quantitative analysis. Sensitivity was sufficient for obtaining meaningful kinetics with a 1 ?M initial substrate concentration.
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Mass-Directed Preparative SFC: An Orthogonal Tool with Reduced Liquid Solvent Usage for High Throughput PurificationIn recent years, improving productivity and cost-savings have become major initiatives in pharmaceutical discovery and development.
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High Sensitivity Native Mass Spectrometry with Cation Exchange ChromatographyThe utility of native high-resolution mass spectrometry (HRMS) in intact protein characterization is rapidly growing because of advances in both ion-exchange chromatography (IEC) as well as MS-compatible buffer systems. MS is a critical component of biotherapeutic characterization, but its combination with traditional chromatographic separations, such as size-exclusion chromatography (SEC) and IEC, has been slow because of the predominant use of high salt mobile phases, which are incompatible with MS. Recently reported methods using cation-exchange chromatography (CEX) with volatile buffer systems for pH gradient elution has given researchers the ability to use these chromatographic techniques with MS detection. In this article a robust, MS-compatible buffer system for high sensitivity IEC with pH gradient elution for charge variant analysis of intact monoclonal antibodies (mAbs) is described.
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Application of a GPC-LC–MS/MS Method for the Determination of 31 Mycotoxins in Edible OIlsGel Permeation Chromatography (GPC) is widely used for sample clean up in mycotoxin analysis. The most commonly described methods use GPC columns packed with SX-3 BioBeads suitable for cleaning Zearalenone, Aflatoxins, and Trichothesenes from edible oils and fatty matrices. Separation of Fumonisins from the oil fraction are inadequate with this column.
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The Power of Planar ChromatographyHigh performance thin-layer chromatography (HPTLC) offers many advantages over conventional separation techniques when applied to complex samples. The Column interviewed Gertrud Morlock from Justus Liebig University Giessen in Germany, on her current research, which involves hyphenating HPTLC with multiple analytical techniques.
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Gradient Performance Tests for Reversed-Phase and Biochemical Applications using High Salt BuffersIn gradient mode, the quality of the analysis will be influenced by the performance of the proportioning and mixing of the eluents at any time during a given chromatogram.
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A Hydrophilic Interaction Chromatography Method for the Purity Analysis of CytosineCytosine (chemical name 4-amino-2-hydroxypyrimidine) is a pyrimidine derivative with a hetereocyclic aromatic ring and two substituents (amine and keto groups) attached and is a polar compound of significant biological and pharmaceutical interest. In response to the intended use of bulk cytosine as a raw material in pharmaceutical manufacturing, a method for the determination of the purity of cytosine was developed.
