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Matrix-Assisted Laser Desorption-Ionization Imaging Mass Spectrometry for Direct Tissue AnalysisA summary of the most recent advances in sample preparation, instrumentation, and data-processing techniques for MALDI-IMS
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Generic UHPLC Method for the Simultaneous Analysis of Compounds with a Wide Range of PolaritiesAppropriate analytical methods are required to evaluate the presence, metabolism, degradation, and removal of specific compounds in complex mixtures. There is an increasing demand to analyze samples with a wide range of polarities in a variety of applications, including environmental analysis, biomarker discovery, and proteomics. Multiple analyses on complementary columns are often needed to cover the separation of all compounds with a large difference in polarity. This article describes a generic method involving an ultrahigh-pressure liquid chromatography (UHPLC) system equipped with two external switching valves to connect hydrophilic interaction liquid chromatography (HILIC) and reversed-phase LC columns in series for the sequential analysis of polar and apolar compounds. The method was successfully applied to separate 32 pharmaceutical compounds with a wide range of polarities, which could be useful for analyzing pharmaceutical compounds in the environment.
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Magnetic Nanoparticles for Solid-Phase ExtractionMagnetic nanoparticles (m-NPs) are becoming important in analytical chemistry as sorbents in dispersive solid-phase extraction (d-SPE) because they simplify the extraction process and save time as a result of their isolation from the sample matrix by an external magnetic field. Many synthetic processes have been developed to fabricate these nanomaterials and an additional coating step is usually included at the end of the synthesis to improve their stability and to avoid the formation of agglomerates. A wide variety of coatings have been used for this purpose to improve selectivity. This manuscript provides an overview of the different synthesis methods, coatings, and applications of m-NPs as sorbents in d-SPE.
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Magnetic Nanoparticles for Solid-Phase ExtractionMagnetic nanoparticles (m-NPs) are becoming important in analytical chemistry as sorbents in dispersive solid-phase extraction (d-SPE) because they simplify the extraction process and save time as a result of their isolation from the sample matrix by an external magnetic field. Many synthetic processes have been developed to fabricate these nanomaterials and an additional coating step is usually included at the end of the synthesis to improve their stability and to avoid the formation of agglomerates. A wide variety of coatings have been used for this purpose to improve selectivity. This manuscript provides an overview of the different synthesis methods, coatings, and applications of m-NPs as sorbents in d-SPE.
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Nanomaterials Have Come to Stay: An Overview of their Use as Sorbents in Sample PreparationThis article reviews how nanomaterials are being used in a variety of sample preparation techniques, such as dispersive solid-phase extraction (dSPE), solid-phase microextraction (SPME), stir-bar sorptive extraction (SBSE), and matrix solid-phase dispersion (MSPD).
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Contemporary Analysis of Chiral MoleculesThe first high performance liquid chromatography (HPLC) column for enantioselective chromatography was introduced commercially in 1981. This chromatographic mode has now become the method of choice for the analysis of chiral pharmaceutical compounds, making previous approaches, such as optical rotation, almost completely obsolete. However, supercritical fluid chromatography (SFC) has been gaining increasing recognition as a complementary technique to HPLC for pharmaceutical enantioselective analysis. Gas chromatography (GC) and capillary electrophoresis (CE) remain very useful for particular applications.
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The Role of Liquid Chromatography–Mass Spectrometry in the Characterization of Therapeutic Monoclonal AntibodiesA review of the central role LC–MS plays in characterizing mAbs and biosimilars, including highlights of top-down and middle-up approaches to measure the intact masses of mAbs and their subunits, the current state of peptide mapping techniques, and glycoprofiling methods.
Latest:
The Role of Liquid Chromatography–Mass Spectrometry in the Characterization of Therapeutic Monoclonal AntibodiesA review of the central role LC–MS plays in characterizing mAbs and biosimilars, including highlights of top-down and middle-up approaches to measure the intact masses of mAbs and their subunits, the current state of peptide mapping techniques, and glycoprofiling methods.
Latest:
The Role of Liquid Chromatography–Mass Spectrometry in the Characterization of Therapeutic Monoclonal AntibodiesA review of the central role LC–MS plays in characterizing mAbs and biosimilars, including highlights of top-down and middle-up approaches to measure the intact masses of mAbs and their subunits, the current state of peptide mapping techniques, and glycoprofiling methods.
Latest:
The Role of Liquid Chromatography–Mass Spectrometry in the Characterization of Therapeutic Monoclonal AntibodiesA review of the central role LC–MS plays in characterizing mAbs and biosimilars, including highlights of top-down and middle-up approaches to measure the intact masses of mAbs and their subunits, the current state of peptide mapping techniques, and glycoprofiling methods.
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Analysis of Pesticides in Citrus Oil Using PTV Backflush with GC–MS-MS Triple Quadrupole for High Sample ThroughputInternational regulations on maximum residue levels (MRLs) of pesticides in food cover hundreds of individual contaminants at the 10 ppb or below range. The analysis of citrus oil for pesticide contamination holds specific challenges.
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Profiling Nonionic Surfactants Applied in Pharmaceutical Formulations Using Comprehensive Two-Dimensional LC with ELSD and MS DetectionComprehensive two-dimensional liquid chromatography (2D-LC) was used for detailed profiling of various nonionic ethoxylated surfactants applied in pharmaceutical formulations. Hydrophilic-interaction chromatography (HILIC) and reversed-phase liquid chromatography (LC) were used as the first and second dimensions, respectively. Detection was performed with evaporative light-scattering detection (ELSD) for general profiling and with single-quadrupole mass spectrometry (MS) for structure elucidation of individual peaks and for class-type confirmation of peak-groups.
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Evaluation of QuECheRS, Cartridge SPE Cleanup, and Gas Chromatography Time-of-Flight Mass Spectrometry for the Analysis of Pesticides in Dietary SupplementsThe authors evaluate a method for detecting pesticide residues in dandelion root powder.
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Matrix-Assisted Laser Desorption-Ionization Imaging Mass Spectrometry for Direct Tissue AnalysisA summary of the most recent advances in sample preparation, instrumentation, and data-processing techniques for MALDI-IMS
Latest:
Matrix-Assisted Laser Desorption-Ionization Imaging Mass Spectrometry for Direct Tissue AnalysisA summary of the most recent advances in sample preparation, instrumentation, and data-processing techniques for MALDI-IMS
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Comparing Multivariate Eluent Design Spaces for Systematic Characterization of (U)HPLC ColumnsPresenting a novel chromatographic modelling method to establish QbD-compliant comparative testing of eluent design spaces.
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UHPLC or HPLC? The Choice is YoursSergio Guazzotti speaks to Janet Kelsey about the advantages of UHPLC over HPLC and issues to consider when selecting this technique.
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Effects of Column Inner Diameter and Packed Bed Heterogeneities on Chromatographic PerformanceIn recent years industry has been moving to columns with smaller and smaller inner diameters - moving from 4.6 mm and 3.0 mm i.d. columns to 2.1 mm, 1.0 mm, and even smaller. While small inner diameter columns have some clear advantages, they also bring challenges. Reduction of extracolumn volumes must be given greater consideration by both customers and manufacturers. This article focuses on the sources of band broadening within high performance liquid chromatography (HPLC) columns with an emphasis on eddy dispersion. The physical mechanisms of dispersion are discussed and a review of the current literature as it pertains to small inner diameter columns is presented.
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Matrix-Assisted Laser Desorption-Ionization Imaging Mass Spectrometry for Direct Tissue AnalysisA summary of the most recent advances in sample preparation, instrumentation, and data-processing techniques for MALDI-IMS
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The Current and Future State of Top-Down Protein Sequencing by ESI-Tandem Mass SpectrometryIn this column, we introduce the basics of today’s approaches for doing intact protein dissociation with mass spectrometry (MS), or top-down sequencing (that is, rather than the more conventional peptide-based “bottom-up” sequencing where future improvements might occur, advantages and limitations of using top-down sequencing, possible applications, and why it has become such an important and pursued research area for many.
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HPLC–MS Characterization of 99.5% Pure Compounds Using Miniaturized Mass DetectorDetecting impurities in any chemical reaction is becoming increasingly important to detect those present at low levels (for example, 0.5%).
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HPLC–MS Characterization of 99.5% Pure Compounds Using Miniaturized Mass DetectorDetecting impurities in any chemical reaction is becoming increasingly important to detect those present at low levels (for example, 0.5%).
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UHPLC Instrument Variations and Approaches to Ease the Method Transfer ProcessUltrahigh-pressure liquid chromatography (UHPLC) instruments from different manufacturers and instruments with different configurations can produce significant variations in chromatographic separation. The variety in instrument configuration increases the complexity of the method development process, which now requires a more thorough evaluation of the effect of instrument variations on the method. The studies presented here determined the typical interinstrument variations in dwell volume, extracolumn dispersion, and mixing efficiency as measured by mobile-phase compositional accuracy. Additionally, the dwell volume and extracolumn dispersion were independently and systematically varied to evaluate the resulting impact on resolution for a small-molecule test mixture during gradient elution. To account for these interinstrument variations, dwell volume and wash-out volume method translation and adjustment techniques were evaluated.
Latest:
UHPLC Instrument Variations and Approaches to Ease the Method Transfer ProcessUltrahigh-pressure liquid chromatography (UHPLC) instruments from different manufacturers and instruments with different configurations can produce significant variations in chromatographic separation. The variety in instrument configuration increases the complexity of the method development process, which now requires a more thorough evaluation of the effect of instrument variations on the method. The studies presented here determined the typical interinstrument variations in dwell volume, extracolumn dispersion, and mixing efficiency as measured by mobile-phase compositional accuracy. Additionally, the dwell volume and extracolumn dispersion were independently and systematically varied to evaluate the resulting impact on resolution for a small-molecule test mixture during gradient elution. To account for these interinstrument variations, dwell volume and wash-out volume method translation and adjustment techniques were evaluated.
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One-Dimensional Simultaneous Achiral and Chiral AnalysisHaving a mixed-mode column that can provide both achiral and chiral resolution in one-dimension (1D) would significantly improve impurity profile understanding and reduce testing workload.
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Improved Analysis of Preservatives in Cosmetics Using a Unique Core-Shell PhasePhenomenex Application Note
