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Purification of synthetic, natural and biological compounds in any quantity usually requires the use of preparative HPLC.

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A 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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In 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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Because 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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The 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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The 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 Samples

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The 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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An evaporative light scattering (ELS) detector is a powerful detection tool if the solutes are less volatile than the eluent. Three main processes occur successively: nebulization, evaporation of the liquid chromatographic (LC) effluent and measurement of the light scattering by the residual particles. This leads to a non-linear calibration curve such as, A= a.m b where A is the peak area,m the sample mass and b the response coefficient measured as the slope of Log A = b>Log m + Log a.

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The authors report the use of LC–MS for monitoring triterpenes in oak heartwoods, wines, and spirits.

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Screening for important factors during method optimization or in robustness testing involves two-level screening designs, such as fractional factorial and Plackett–Burman designs, as described in Part 1. This second part on screening designs discusses the experimental protocol for executing these designs and the data analysis of their results.

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An isocratic HPLC method for the determination of phenol and nitrophenols (4-nitrophenol, 2-nitrophenol, 4,6-dinitro-o-cresol and 2,4-dinitrophenol) has been developed and validated using 2-chlorophenol as internal standard (IS) and a monolithic column in tap water samples. Prior to HPLC, the method requires solid-phase extraction (SPE) using polymeric Lichrolut EN cartridges. The method development involved the study of methanol and acetonitrile as organic modifiers, pH and flow-rate using a Chromolith RP-18e (150 mm × 4.6 mm I.D.) column. After comparing the performance of the separations obtained with both organic modifiers, the optimum separation of these compounds was achieved using 50 mM acetate buffer (pH 5.0)-acetonitrile (80:20, v/v) as mobile phase, 3 mL min-¹ flow-rate and UV detection at maximum absorbance wavelength. Under these conditions, all analytes were separated (Rs > 2.0) in an analysis time of less than 3.5 min and the most important validation parameters were evaluated. The recoveries obtained in the accuracy test for all phenols studied were in the 90–112% range using a preconcentration factor of 40, and the intraday and interday precisions [expressed as coefficient of variation (CV)] were smaller than 15%. Finally, the proposed method was applied to wastewater samples from several industries.

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Purification of synthetic, natural and biological compounds in any quantity usually requires the use of preparative HPLC.

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Akzo Nobel

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An evaporative light scattering (ELS) detector is a powerful detection tool if the solutes are less volatile than the eluent. Three main processes occur successively: nebulization, evaporation of the liquid chromatographic (LC) effluent and measurement of the light scattering by the residual particles. This leads to a non-linear calibration curve such as, A= a.m b where A is the peak area,m the sample mass and b the response coefficient measured as the slope of Log A = b>Log m + Log a.

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This article looks at the use of electromigration techniques to determine microorganisms, such as viruses, bacteria and other biologically important macromolecules (erythrocytes), in medical analyses. It was found that electromigration techniques could be used for the identification of several viruses, including the identification of a specific marker for the Hepatitis C virus infection and another for a urinary tract infection. The determination of cell viability and the quality control of probiotics and consumer products that contain active bacteria is also possible using electromigration. Special attention is paid to the modification of capillary wall surfaces using different monomers and the application of monolithic columns to determine active bacteria in pharmaceutical products using capillary electrochromatography (CEC) conditions. This approach represents a new frontier for separation science and the possibility to apply it in medical diagnosis.

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As environmental legislation becomes more stringent, the need to deliver quantitative results in shorter times and greater volumes is necessary for routine environmental analysis. Most of the high-throughput screening methods used to analyze pharmaceutical compounds are, however, useless for environmental monitoring. This is because these methods primarily aim to retrieve as much information from a single sample using the broadest range of techniques. The chromatographic separation process is considered to be the bottleneck in the process. This is not the situation for environmental procedures, in which the bottleneck is the sample preparation step and is usually very tedious and time-consuming.

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The authors report the use of LC–MS for monitoring triterpenes in oak heartwoods, wines, and spirits.

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The authors describe a new instrumental method for determining phthalate esters using positive chemical ionization and retention-time locking GC.

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One of the biggest problems facing researchers involved in pharmacogenomics is analysing the recombinant proteins of interest to monitor if they are in a folded state. This article describes a rapid and economical method using asymmetric flow field-flow fractionation combined with multi-angle light scattering (AF4–MALS) to characterize refolded proteins, which overcomes some of the disadvantages associated with other techniques.

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This article assesses the advantages of including certified reference materials in collaborative method validation studies in food analysis. A recently conducted collaborative trial on the determination of acrylamide in bakery and potato products is described to illustrate this.

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The implementation and validation of a new site-wide chromatography data system for a major active pharmaceutical ingredient custom manufacturer provided the opportunity to map and optimize the GMP and ISO business processes to use electronic signatures effectively. This article describes the process optimization and how it integrates with the validation activities of the system. This overall approach provides substantial business benefits from the use of electronic signatures as evidenced by the savings resulting from process improvement and by the fact that the non-GMP laboratories implemented a similar process to analyse and approve results electronically.

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In the world of liquid chromatography, innovative strides in column technology continue to take place. We are also reminded that there is always more to learn about “well-known” methodologies, and our craft is continuously influenced by important social concerns.

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Conventional pyrolysis can cause defunctionalization of polar structural moieties carrying functional groups, which leads to biased results.

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The authors descrive the use of GC–MS to isolate and identify potentially toxic compounds in concentrated extracts of sewage treatment plant effluents.

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This is the second installment of a two-part series on the practical aspects of configuring and operating a nano liquid chromatography-mass spectrometry (LC-MS) system.

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This 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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This article describes a method development approach that uses different packing materials and mobile-phase pH levels to optimize the chromatographic separation of degradation products from active ingredients.