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Solvent Selection in Countercurrent Chromatography Using Small-Volume Hydrostatic ColumnsHow to use small columns to test potential biphasic liquid systems for use in large-scale countercurrent chromatography separations
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Dual Flow ChromatographyDual flow chromatography (DFC) separations are performed with back and forth flow for rapid method development, design of experiments (DOE), quality-by-design (QbD), or high-throughput chromatographic purification. Although different than conventional unidirectional flow through chromatography, chromatographic principles still control the separations. Selectivity coefficients and Langmuir adsorption isotherms control the separation chemistry properties of the column and dictate the mobile phase conditions needed to achieve separation. However, the kinetic rates of diffusion and interaction of mobile phase molecules with the stationary phase, column channeling, and other column properties are not germane to the practice of DFC. Chromatographic conditions developed with DFC can be scaled to any size, including laboratory and industrial preparative columns.
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Simultaneous Determination of Plant Growth Regulators in Bean Sprouts by UHPLC Coupled with MS/MSA rapid and sensitive ultrahigh-pressure liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method was developed to simultaneously determine six plant growth regulators in bean sprouts with a simple preparation. Analyte extraction from samples was effectively performed using liquid–liquid extraction (LLE) by acetonitrile. Chromatographic separation was conducted on a C18 reversed-phase column with gradient elution. The analytes were detected by tandem quadrupole MS after negative electrospray ionization by multiple reaction monitoring. The developed method was validated by testing method specificity, matrix effect, sensitivity, linearity, accuracy, and precision.
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Analysis of Near 400 Pesticides in Tea via LC–MS/MS: Simple Sample Preparation and APCI to Improve Analyte CoverageThis method greatly facilitates the analysis of a large number of pesticides.
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Simultaneous Determination of Plant Growth Regulators in Bean Sprouts by UHPLC Coupled with MS/MSA rapid and sensitive ultrahigh-pressure liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method was developed to simultaneously determine six plant growth regulators in bean sprouts with a simple preparation. Analyte extraction from samples was effectively performed using liquid–liquid extraction (LLE) by acetonitrile. Chromatographic separation was conducted on a C18 reversed-phase column with gradient elution. The analytes were detected by tandem quadrupole MS after negative electrospray ionization by multiple reaction monitoring. The developed method was validated by testing method specificity, matrix effect, sensitivity, linearity, accuracy, and precision.
Latest:
Simultaneous Determination of Plant Growth Regulators in Bean Sprouts by UHPLC Coupled with MS/MSA rapid and sensitive ultrahigh-pressure liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method was developed to simultaneously determine six plant growth regulators in bean sprouts with a simple preparation. Analyte extraction from samples was effectively performed using liquid–liquid extraction (LLE) by acetonitrile. Chromatographic separation was conducted on a C18 reversed-phase column with gradient elution. The analytes were detected by tandem quadrupole MS after negative electrospray ionization by multiple reaction monitoring. The developed method was validated by testing method specificity, matrix effect, sensitivity, linearity, accuracy, and precision.
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Superheated Water as an Extraction Solvent in Sample PreparationPressurized high temperature or superheated water is a green extraction solvent used in food, environmental, and traditional medicine studies for the extraction of non-polar and polar analytes including essential oils and spices, agrochemicals, pharmaceuticals, and petrochemicals.
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HPLC 2024 PreviewA look at what’s in store for chromatographers who attend HPLC 2024 in Denver, Colorado, USA from 20–25 July 2024.
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Whither Gas Chromatography? New Tools ~ New SolutionsWe might well ask “Where is gas chromatography (GC) heading?” For many analysts, the answer may be just “more of the same,” reflecting that GC is mature and that most analysis tasks and sample types have been tried and tested. In this scenario, any changes to the basic method may be marginal—sample introduction, and maybe a new detector? But beneath this status quo is an undercurrent of passion, excitement, and power.
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The LCGC Blog: Historical (Analytical) Chemistry LandmarksThe American Chemical Society’s National Historic Chemical Landmarks program highlights sites and people that are important to the field of chemistry. How are analytical chemistry and separation science recognized within this program?
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My Mentors, Colleagues, and Friends in Separation Science and Technology, Part IIThis final installment of Klaus Unger's personal reflections and scientific activities covers from 1990 until his retirement in 2010.
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The LCGC Blog: Celebrating Women in Separation Chemistry at Pittcon 2024In this edition of The LCGC Blog, Emanuela Gionfriddo discusses the two world-class scientists and trailblazer women in separation chemistry and the awards they received at Pittcon 2024.
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Data HandlingA snapshot of key trends and developments in the data handling sector according to selected panelists from companies exhibiting at Analytica 2018.
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2017 Salary Survey: Increase in Workload, But Still OptimisticWe present our analysis of LCGC’s first reader survey on salary, workload, job satisfaction, and the job market in general. The survey shows that workloads and stress levels have increased for many. Nevertheless, most view the employment outlook as good, if not excellent, and indicate a high level of satisfaction with their present jobs.
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Real-Time Monitoring of Volatile Organic Compounds in Ambient Air Using Direct Injection Mass Spectrometry (Sept 2024)In this article, the results of a DIMS air monitoring campaign in Auckland, New Zealand, are described. Real-time SIFT–MS measurements were obtained at three sites over a period of several weeks. At each site, SIFT–MS provided effective on-site analysis to sub-ppbV levels with better than 1-min time resolution.
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High-Throughput, Routine, and Comprehensive Proteome AnalysisSee how the µPAC™ capLC LC–MS column can help increase sample throughput, and at the same time maintain the highest separation efficiency and sensitivity.
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SFC–GCxGC to Analyse Matrices from Petroleum and CoalSFC–GCxGC is shown to be useful in fossil fuel analysis. Practical examples for the analysis of complex matrices are described.
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Liquid Chromatography–Atmospheric Pressure Photoionization-Mass Spectrometry Analysis of the Nonvolatile Precursors of Rancid Smell in MayonnaiseFor lipid-containing food products like mayonnaise, determining nonvolatile lipid oxidation products, the precursor compounds for rancidity, makes it possible to predict product shelf life at an earlier stage in product development. A method based on normal-phase liquid chromatography with atmospheric pressure photoionization-mass spectrometry (LC–APPI-MS) was developed for this purpose.
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Determination of PBDEs in River Water Utilizing Automated SPE in Conformance with EU Standards at IRSAPolybrominated diphenyl ethers (PBDEs) are a worldwide contamination problem. Structurally similar to polychlorinated biphenyl (PCBs), these compounds are long-lived in the environment and can bioaccumulate throughout the food chain. The health hazards of these chemicals have attracted increasing scrutiny and, as such, a great deal of research and regulations have been implemented to manage and control them.
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Analyzing Multisegmented Block Copolymers by SEC-MALS-IV“Click” chemistry is a class of efficient and selective reactions that is characterized by quantitative yields, tolerance to a broad range of functional groups, facile experimental setup, and minimal synthetic workup. This class of reactions combines particularly well with controlled radical polymerization methods, such as atom transfer radical polymerization (ATRP), and the two techniques have been prolifically employed for the synthesis of a wide variety of novel polymeric materials, including (multi) block copolymers, stars, brushes, and gels. This note describes the analysis of multisegmented block copolymers prepared by click-coupling of block copolymers synthesized by ATRP.
