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Are You Sure You Understand USP <621>?In this column, we look at the current version and the update of USP <621> on high-performance liquid chromatography (HPLC) that becomes effective 1st May 2025.
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The Application of Multiplexed Microemulsion Electrokinetic Chromatography for the Rapid Determination of log POW Values for Neutral and Basic CompoundsThis article illustrates the use of multiplexed microemulsion electrokinetic chromatography with UV detection to develop a rapid approach for obtaining log POW values of neutral and basic compounds.
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Optimizing Column Lifetime of TSK-GEL Size Exclusion ColumnsColumn lifetime is a more and more important issue when developing an analytical method for HPLC. Besides sample treatment, column cleaning and storage, operational parameters of the analytical method will have an influence on column lifetime. This question may not always be addressed early enough in the methods development process.
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Determination of PAHs in Combustion-Related Samples via Multidimensional Chromatographic MethodsGas chromatography–mass spectrometry (GC–MS), reversed-phase LC with stop-flow fluorescence (FL), and constant energy synchronous fluorescence spectroscopy (CESFS) are explored to determine PAH isomers in three combustion-related standard reference materials.
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My 50+ Years in ChromatographyThe former "Milestones in Chromatography" editor returns to give readers the story of his time in the field.
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Stationary Phases for Planar Separations — Plates for Modern TLCThe authors provide the latest information on new stationary phases for modern TLC and high performance TLC (HPTLC), along with helpful hints on how to get the most out of this flexible form of chromatography.
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Factors and Parameters that Directly Affect Recovery of Collected Fractions in Preparative HPLCPurification of synthetic, natural and biological compounds in any quantity usually requires the use of preparative HPLC.
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Analysis of Fructose, Glycine and Triglycine using UV/vis Detection and Evaporative Light-Scattering DetectionThe development of a method for the simultaneous determination of glycine, triglycine and fructose using UV/vis and evaporative light-scattering is presented. The study formed part of a research project dealing with the recovery of functional peptides from aqueous streams on an industrial scale using absorption or related technologies.
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Influence of Na+- and K+- Concentration in Solvents on Mass Spectra of Peptides in LC/ESI–MSIn this article, the authors examine the concentration-dependent influence of Na+- and K+ ions on mass spectra of peptides, with human gastrin as a model peptide using LC/ESI–MS as the selected ionization technique.
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GC Analysis of Trihalomethanes in Drinking Water — A Rapid and Direct Quantitative MethodThe authors describe a GC assay of trihalomethanes in drinking water.
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Analysis of Fructose, Glycine and Triglycine using UV/vis Detection and Evaporative Light-Scattering DetectionThe development of a method for the simultaneous determination of glycine, triglycine and fructose using UV/vis and evaporative light-scattering is presented. The study formed part of a research project dealing with the recovery of functional peptides from aqueous streams on an industrial scale using absorption or related technologies.
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Directions in Automated Sample Preparation of ProteinsThe guest authors discuss current procedures for protein sample preparation, protein analysis, and automation.
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Analysis of Combinatorial Natural Products by HPLC and CEIn this article the authors report on a combinatorial natural product discovery methodology that uses a viral vector system to transfer secondary metabolite-related enzymes from C. roseus to tobacco cell cultures. Using high-resolution separation techniques, including HPLC, CE and MS, they describe the analysis of secondary metabolite patterns.
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Simultaneous Determination of Chelating Agents by Ion-Suppression and Ion-Pair Chromatography in WastewaterChelating agents such as NTA, CDTA and DTPA are considered by ANDRA (the French national agency for radioactive waste management) as compounds to be investigated because they may enhance the release of radioactive isotopes in the environment.
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Estimation of Triterpenes in Wines, Spirits, and Oak Heartwoods by LC–MSThe authors report the use of LC–MS for monitoring triterpenes in oak heartwoods, wines, and spirits.
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Tandem GC–MS Analysis of Pesticides in Food Oils by Large Volume Injection with a Back-flush OptionAs the global sourcing of foodstuffs becomes more common, the number of pesticide analyses performed continues to increase to test these sources for compliance with various regulations. The sheer number of analyses dictates that utilized methods must be reliable, robust and inexpensive.
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Benchmarking for Analytical Methods: The Horwitz CurveAnalytical chemists are concerned with the quality of their methods and results. An important question in this context is whether the precision of a newly developed and validated method is up to standard. In other words: is the precision of the newly developed method comparable to what could be expected? This article looks at how the Horwitz equation can answer this. It also describes the results of an extensive study involving 10000 laboratories which indicates that the relative reproducibility approximately doubles for every 100-fold decrease in concentration and that, surprisingly, it does not depend on the type of material or method.
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On-line Supercritical Fluid Extraction-Capillary Gas Chromatography for the Analysis of DieselDirect coupling of SFE with GC has advantages over the off-line alternative.
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Analysis of Combinatorial Natural Products by HPLC and CEIn this article the authors report on a combinatorial natural product discovery methodology that uses a viral vector system to transfer secondary metabolite-related enzymes from C. roseus to tobacco cell cultures. Using high-resolution separation techniques, including HPLC, CE and MS, they describe the analysis of secondary metabolite patterns.
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A Chromatographic Screening Method to Identify Agents that Reverse Intrinsic Drug Resistance in Colon Cancer CellsConjugation catalysed by the UDP-glucuronosyltransferase (UGT) superfamily of drug-metabolizing enzymes is an important mechanism of anticancer drug resistance in colon cancer cells. The mechanism manifests itself by a reduction in the intracellular concentrations of the parent drug through increased export of the glucuronide metabolites to the extracellular compartment. Modulation by an inhibitor of UGT inhibits the formation of metabolites and restores intracellular concentrations of the drug. This article describes a screening method using HT29 human colon cancer cells and based on HPLC methodology that allows the identification of effective modulators of the glucuronidation mechanism of drug resistance. A rapid solid-phase sample preparation technique using C2-bonded 40 ?m silica particles was developed for the extraction of cell lysates and culture media without degradation of unstable parent compounds and their glucuronides or artefactual in situ formation of metabolites.
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System Suitability and Validation for Chiral Purity Assays of Drug SubstancesMeasurement of chiral purity is a necessary means of quality control for drug substances that exhibit chiral centers. This article describes a simple and practical approach to setting up system suitability and validation for chiral purity assays.
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The Application of Multiplexed Microemulsion Electrokinetic Chromatography for the Rapid Determination of log POW Values for Neutral and Basic CompoundsThis article illustrates the use of multiplexed microemulsion electrokinetic chromatography with UV detection to develop a rapid approach for obtaining log POW values of neutral and basic compounds.
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Analysis of Biodiesels Using LC–MSPreliminary studies of biodiesel samples by a high speed LC–MS system using electrospray ionization and a patented cone-wash feature demonstrate that LC–MS reduces the analysis time to 20 minutes and reveals information about higher molecular weight compounds in biodiesel while still detecting many low molecular weight chemicals, including FAMEs, at high sensitivity.
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Factors and Parameters that Directly Affect Recovery of Collected Fractions in Preparative HPLCPurification of synthetic, natural and biological compounds in any quantity usually requires the use of preparative HPLC.
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Simplifying Mass Spectrometry Through New Ionization Technology: Application to Drugs and Clinical AnalysesA newly discovered method, matrix-assisted ionization (MAI), is described for generating gas-phase ions from volatile and nonvolatile compounds. The method is both simple and sensitive.
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Selecting the Best Curve FitIn this month's column, the authors present a relatively simple method for selecting the appropriate curve-fitting function and thus ensure that the requirements of current guidelines can be met.
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Forensic Drug Screening by LC–MS Using Accurate Mass MeasurementBecause of progress in liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS) instrumentation, data processing and reporting, the measurement of compounds' accurate masses is becoming routine practice in screening analysis based on target databases. As such databases of monoisotopic masses can be easily updated with recent data from the literature; rapid characterization of new compounds and metabolites is possible without the need for primary reference standards. This approach has already been established in comprehensive toxicological urine screening and in analysis of drugs-of-abuse in seized street drug samples. Currently, a mass accuracy within 5 ppm can be routinely achieved, and confirmation via a numerical isotopic pattern match (SigmaFit) is provided by a new generation LC/TOF-MS instrument.
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Experimental Proofs of a Correlation Between the Coefficients for the Slope of the Response Line and the Response Factor of an ELSDThe authors describe a study that was conducted to evaluate the correlation between the slope of the response line and the response factor of an ELSD that are ordinarily regarded as independent numerical coefficients.
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Automation of Sample Preparation for GenomicsThe guest authors review the commonly used sample preparation procedures for genomic nucleic acid purification and introduce the automation choices for high-throughput genomic sample preparation.
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Advances in Sample Preparation: Removing Phospholipids from Biological SamplesAdvances in Sample Preparation: Removing Phospholipids from Biological Samples
