Related books on 'chromatography'
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publisher: Wiley, published: 2011-09-21 ASIN: 0470434074 EAN: 9780470434079 sales rank: 1363252 This book provides a detailed description of various multidimensional chromatographic separation techniques. The editor first provides an introduction to the area and then dives right into the various complex separation techniques. While still not used routinely comprehensive chromatography techniques will help acquaint the readers with the fundamentals and possible benefits of multi-dimensional separations coupled with mass spectrometry. The topics include a wide range of material that will appease all interested in either entering the field of multidimensional chromatography and those looking to gain a better understanding of the topic. |
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by: Douglas T. Gjerde publisher: Wiley-VCH, published: 2002-04-30 ASIN: 3527302441 EAN: 9783527302444 sales rank: 887698 This book describes a powerful and effective tool for the molecular biologist researcher. Readers will discover how DNA chromatography can be used in their own work. Intended as an introduction for the molecular biologist reader, this will also serve as a practical guide for the experienced user. The clear and concise writing style is also attractive to the chemist who wants to learn more about molecular biology. |
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by: Fulton G. Kitson publisher: Academic Press, published: 1996-09-03 ASIN: 0124833853 EAN: 9780124833852 sales rank: 1157604 This guide provides, under one cover, a wealth of practical information designed to facilitate the effectiveness of the GC/MS user. Separation conditions for numerous compound types are provided along with derivatized and underivatized compounds. A section on how to interpret mass spectral data, an extensive correlation of ion masses and neutral losses with possible structures, and examples of mass spectra are provided to further aid structure determination. Also included are basic information on instrumentation, ionization methods, quantitation, tips on the operation of mass spectrometers, the best derivatization procedures for a variety of compound types, troubleshooting techniques, and a variety of other information found to be useful to the practicing user of GC/MS instrumentation. This guide would be immediately valuable to the novice as well as the experienced GC/MS user who may not have the breadth of experience covered in this book. Key Features * Condenses and organizes recent and essential information for new and experienced GC/MS users * Comprehensively indexed and referenced * Includes practical methods of analysis * Serves as a text reference for short practical courses on the subject |
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by: T. Kovalczuk publisher: Elsevier, published: 2006-09-01 ASIN: B000P6OTYM This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Potential of ultra-performance liquid chromatography (UPLC) separation strategy coupled with tandem (in space) mass spectrometric detection (MS/MS) in multiresidue pesticide analysis was critically assessed. Performance parameters such as number of theoretical plates, height of theoretical plate, peak symmetry and peak capacity were measured/calculated on the basis of data generated by analysis of apple extracts containing 17 (semi)polar pesticides representing various classes of active ingredients of widely used crop protective preparations. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) procedure provided improved chromatographic parameters resulting in significantly increased sample throughput including lower solvent consumption and lower limits of quantitation (LOQs) for most of target analytes compared to common method employing conventional high-performance liquid chromatography (HPLC) separation. |
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by: T.R. Besanger publisher: Elsevier, published: 2006-03-30 ASIN: B000PBZYYG This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Our group recently reported on the application of protein-doped monolithic silica columns for immobilized enzyme reactor chromatography, which allowed screening of enzyme inhibitors present in mixtures using mass spectrometry for detection. The enzyme was immobilized by entrapment within a bimodal meso/macroporous silica material prepared by a biocompatible sol-gel processing route. While such columns proved to be useful for applications such as screening of protein-ligand interactions, significant amounts of entrapped proteins leached from the columns owing to the high proportion of macropores within the materials. Herein, we describe a detailed study of factors affecting the morphology of protein-doped bioaffinity columns and demonstrate that specific pH values and concentrations of poly(ethylene glycol) can be used to prepare essentially mesoporous columns that retain over 80% of initially loaded enzyme in an active and accessible form and yet still retain sufficient porosity to allow pressure-driven flow in the low @mL/min range. Using the enzyme @c-glutamyl transpeptidase (@c-GT), we further evaluated the catalytic constants of the enzyme entrapped in capillary columns with different silica morphologies as a function of flowrate and backpressure using the enzyme reactor assay mode. It was found that the apparent activity of the enzyme was highest in mesoporous columns that retained high levels of enzyme. In such columns, enzyme activity increased by ~2-fold with increases in both flowrate (from 250 to 1000nL/min) and backpressure generated (from 500 to 2100psi) during the chromatographic activity assay owing to increases in k"c"a"t and decreases in K"M, switching from diffusion controlled to reaction controlled conditions at ca. 2000psi. These results suggest that columns with minimal macropore volumes (<5%) are advantageous for the entrapment of soluble proteins for bioaffinity and bioreactor chromatography. |
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by: V. Diamantis publisher: Elsevier, published: 2006-07-28 ASIN: B000PDT8LE This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: Bio-ethanol and biogas produced during the anaerobic conversion of organic compounds has been a subject of great interest since the oil crisis of the 1970s. In ethanol fermentation and anaerobic treatment of wastewaters, end-product (ethanol) and intermediate-products (short-chain fatty acids, SCFA) cause inhibition that results in reduced process efficiency. Control of these constituents is of utmost importance for bioreactor optimization and process stability. Ethanol and SCFA can be detected with precision by capillary gas chromatography usually conducted in off-line measurements. In this work, an on-line monitoring and controlling system was developed and connected to the fermenter via an auto-sampling equipment, which could perform the feeding, filtration and dilution of the sample and final injection into the gas chromatograph through an automation-based programmed procedure. The sample was continuously pumped from the recycle stream of the bioreactor and treated using a microfiltration unit. The concentrate was returned to the reactor while the permeate was quantitatively mixed with an internal standard solution. The system comprised of a gas chromatograph with the flow cell and one-shot sampler and a PC with the appropriate software. The on-line measurement of ethanol and SCFA, directly from the liquid phase of an ethanol fermenter and a high-rate continuous mode anaerobic digester, was accomplished by gas chromatography. Also, this monitoring and controlling system was proved to be effective in the continuous fermentation of alcohol-free beer. |
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by: N. Ratola publisher: Elsevier, published: 2006-07-28 ASIN: B000PDT8LY This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: As the performances of analytical instrumentation are being gradually enhanced, the limits of detection become increasingly lower, allowing more environmental contaminants to be determined in different matrices. Problems emerge when dealing with data from different origins, once the uncertainty of the results is difficult to be compared, especially if its calculation procedure is rather different, as very often happens. Samples of two organochlorine pesticides of somewhat opposite characteristics (lindane and heptachlor, classified as persistent organic pollutants-POPs) were analyzed in aqueous media using headspace solid-phase microextraction (SPME) prior to gas chromatography-electron capture detection (GC-ECD) and this methodology was in-house validated. Detection limits of 0.097 and 0.050@mgl^-^1, average intermediate precision of 11.6% and 27.5%, and average recovery of 95.6% and 103.0%, for lindane and heptachlor, respectively, were found. In the absence of available interlaboratory studies to assess the reliability of the results, the expanded uncertainty was calculated following two different approaches (bottom-up/Eurachem and modified top-down) and the results were compared. Globally it was clearly shown that, for both pesticides, the lower the concentration range, the higher the uncertainty associated to the results. Expanded uncertainties estimated by bottom-up/Eurachem approach varied from 51% to 14% for a lindane concentration range of 0.1-1@mgl^-^1, and from 48% to 24% for a heptachlor range of 0.1-2@mgl^-^1. Modified top-down approach pointed to 44% (lindane and heptachlor) in the same ranges, meaning that a uniform procedure for uncertainty estimation should be adopted. |
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by: M.H. Spyridaki publisher: Elsevier, published: 2006-07-28 ASIN: B000PDT8NC This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: A new liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) (n) ion trap method for the determination of corticosteroids in urine has been developed and validated. Some anabolic agents, such as epitrenbolone, trenbolone, 2-hydroxymethylformebolone, tetrahydrogestrinone, gestrinone and formoterol were included in the LC-ESI-MS method. Matrix interference, specificity, identification capability, carry over and robustness were estimated as validation parameters. Recoveries ranged from 74 to 113% at the minimum required performance limit (MRPL), which is 30ngmL^-^1 for corticosteroids and 10ngmL^-^1 for anabolic agents. Methods for the confirmation and quantification of norpseudoephedrine, ephedrine, methylephedrine, salbutamol, morphine and morphine glucuronide were also developed and validated and in order to minimize analysis time, direct urine injection was used. These methods proved to be specific, accurate and precise across a calibration range for each substance since matrix interference, specificity, carry over, within and between run precision, limit of detection, limit of quantification, intermediate precision and uncertainty were estimated. |
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by: L. Urbanek publisher: Elsevier, published: 2006-07-28 ASIN: B000PDT8O6 This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: In this study a novel, simple and rapid reversed-phase high performance liquid chromatography (HPLC) procedure for simultaneous determination of vitamins A and E (retinol and alpha-tocopherol) in blood serum has been developed and validated using monolithic column and diode-array detection (DAD). The monolithic column Chromolith Performance RP-18e (100mmx4.6mm) was operated at ambient temperature. One hundred percent methanol at flow rate 2.5mlmin^-^1 was used as a mobile phase. Detection of both compounds was performed with diode-array detector, retinol was monitored at 325nm and alpha-tocopherol at 295nm. The linear dependence between peak area and concentration ranged from 0.25 to 10.00@mmoll^-^1 for retinol and 0.5-50.0@mmoll^-^1 for alpha-tocopherol. The limit of detection (LOD) for retinol was 0.02@mmoll^-^1 and limit of quantification (LOQ) was 0.07@mmoll^-^1. The limit of detection (LOD) for alpha-tocopherol was 0.1@mmoll^-^1 and limit of quantification (LOQ) was 0.3@mmoll^-^1. Retinol was eluted in 0.8min and alpha-tocopherol in 1.4min. The simultaneous analysis of vitamin A and E can be achieved in less than 2min. The implementation of monolithic column Chromolith Performance shortens the time of analysis of both vitamins four times in comparison with using traditional particulate column Pecosphere C18 (150mmx4.6mm), 5@mm. This fact may play an important role for routine clinical analysis of biological samples. |
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by: A. Varvaresou publisher: Elsevier, published: 2006-07-28 ASIN: B000PDT8OQ This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Description: A reversed-phase ion-pair high-performance liquid chromatographic method was developed and validated for the determination of magnesium ascorbyl phosphate and melatonin in cosmetic creams. The determination was performed on a BDS C 18 analytical column (250x4.6mm i.d., 5@mm particle size); the mobile phase consisted of 0.020M tetrabutylammonium hydroxide and 0.025M potassium dihydrogen phosphate (pH 6.8) mixed with acetonitrile in a ratio (77:23, v/v) and pumped at a flow rate 1.00mlmin^-^1. The UV detector was operated at 260nm. The retention times of the magnesium ascorbyl phosphate, melatonin and chlorthalidone that was used as internal standard, were 6.55, 9.18 and 11.07min, respectively. Calibration graphs are linear (r better than 0.9990, n=6), in concentration range 1.00-10.00@mgml^-^1 for magnesium ascorbyl phosphate and 0.63-6.25@mgml^-^1 for melatonin. The intra- and inter-day R.S.D. values were less than 6.0%, while the relative percentage error E"r was less than 3.5% (n=5). The quantitation limits were 0.69 and 0.47@mgml^-^1, for magnesium ascorbyl phosphate and melatonin, respectively. The method was applied to the analysis of a cosmetic cream and proved to be suitable for rapid and reliable quality control. |