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Topic: High pressure liquid chromatography

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	High performance liquid chromatography Summary
		In liquid chromatography, a mixture of molecules dissolved in a solution (mobile phase) is separated into its constituent parts by passing through a column of tightly packed solid particles (stationary phase).
		High performance liquid chromatography (HPLC) is a form of column chromatography used frequently in biochemistry and analytical chemistry.
		HPLC is used to separate components of a mixture based on a variety of chemical interactions between the substance being analyzed (analyte) and the chromatography column.
	www.bookrags.com /High_performance_liquid_chromatography (2504 words)

	HPLC - High Performance Liquid Chromatography Primer (Site not responding. Last check: 2007-09-10)
		Liquid chromatography can be performed in three primary approaches.
		The name “HPLC” originally referred to the fact that high pressure was needed to generate the flow required for liquid chromatography in packed columns.
		High Performance Liquid Chromatography (HPLC) is now one of the most powerful tools in analytical chemistry, with the ability to separate, identify and quantitate the compounds that are present in any sample that can be dissolved in a liquid.
	www.waters.com /watersdivision/ContentD.asp?watersit=JDRS-5LTGBH (1013 words)

	Single-pump multiple stroke proportioning for gradient elution liquid chromatography - Patent 4437812
		In particular, this invention is concerned with the use of a single reciprocating pump for gradient elution liquid chromatography, and provides a technique for minimizing inaccuracies in the relative concentrations of the solvent components pumped from a plurality of reservoirs for passage through a chromatographic column.
		Such residual liquid was compressed during the pumping stroke; and as the piston began to withdraw from the pump chamber in preparation for the next fill stroke, this compressed liquid tended to spit back into the particular component reservoir for which the corresponding proportioning valve was open.
		This suction of reservoir liquid into the pump chamber prior to the onset of the scheduled proportioning according to the gradient setting means often resulted in significant inaccuracies in the concentration ratio of the solvent components, particularly near the 0% and 100% concentration levels.
	www.freepatentsonline.com /4437812.html (6275 words)

	High Pressure Liquid Chromatography
		It is possible to apply such pressure from a cylinder of compressed gas, but most systems use a reciprocating piston pump or diaphragm pump with some means of damping the pressure fluctuations from the piston.
		Liquid chromatography with the stationary phase less polar than the mobile phase is called “reverse phase”, but is now the common situation.
		Ion-pair chromatography: In liquid chromatography, strongly ionized sample components which would not partition into the liquid phase can be combined with large ions having the opposite charge [such as an alkyl sulfonate (negative) or a tetrabutylammonium (positive)] to produce “ion pairs” that act like a compound and will partition.
	www.dyerlabs.com /chemistry/highpressure.html (1328 words)

	Hydraulic pulse dampener employing two stiff diaphragms and nesting members - Patent 4552182
		As pressure pulses occur, the tube flexes towards a circular shape, thereby increasing volume and alleviating the pressure of the pulse.
		The pressures that may be damped by the pulse dampener of the present invention can be varied from a few psi to pressures as high as 6000 psi.
		As average pressure continues to increase, or as pressure pulses are experienced, diaphragm 20 is deformed further in the regions between the midpoint 23 and the edges of receiving member 21 until diaphragm 20 fully nests in recess 24.
	www.freepatentsonline.com /4552182.html (2841 words)

	Organic Chemistry 3510, High Performance Liquid Chromatography
		Column Chromatography: In a typical column chromatography separation, the mixture of compounds to be separated is introduced onto the top of a cylindrical glass column uniformly packed with fine alumina or silica gel particles.
		High Performance Liquid Chromatography: One way to obtain better separations with tightly packed columns is to use a pump to force the solvent through the column packing.
		Since such tightly packed columns are susceptible to plugging, high quality solvents are used with special filtration of the solvent before it enters the pump and often a guard column (slightly larger diameter packing particles) before the main column.
	www.uwplatt.edu /~sundin/351/351hHPLC.htm (1349 words)

	High performance liquid chromatography - Wikipedia, the free encyclopedia
		In isocratic HPLC the analyte is forced through a column of the stationary phase (usually a tube packed with small round particles with a certain surface chemistry) by pumping a liquid (mobile phase) at high pressure through the column.
		The sample to be analyzed is introduced in a small volume to the stream of mobile phase and is retarded by specific chemical or physical interactions with the stationary phase as it traverses the length of the column.
		A normal gradient for reverse phase chromatography might start at 5% methanol and progress linearly to 50% methanol over 25 minutes, depending on how hydrophobic the analyte is. The gradient separates the analyte mixtures as a function of the affinity of the analyte for the current mobile phase composition relative to the stationary phase.
	en.wikipedia.org /wiki/High_performance_liquid_chromatography (2223 words)

	Journal of Analytical-Science.com : High Pressure Liquid Chromatography
		Also discussed is the use of conventional fibre-based SPME coupled to HPLC for the analysis of non-ionic surfactants in wastewater, and an application of the new technology of In-Tube SPME coupled to HPLC for the automated analysis of phenyl urea pesticides.
		While fibre-based HPLC has the advantage of eliminating the solvent front peak from the chromatogram, the method does suffer peak broadening in applications where analytes are slow to desorb from the fibre.
		High levels of competing substances such as salts are known to interfere with this analysis, requiring in many cases that samples be pre-extracted before analysis.
	www.analytical-science.com /Journal/liquidchromatography_2002.htm (5094 words)

	Session Summary
		Hardware (pumps, valves, injectors, connecting tubing, columns) must be made which can withstand such high pressure while in contact with solvents ranging from aqueous salt solutions to polar and non-polar organic solvents.
		Analytical pyrolysis extends gas chromatography (GC) to enable analysis of polymers that are not volatile due to their high molecular weight.
		High spatial resolution can be obtained by coupling a microscope to the laser system to allow analysis to be focused on micron spot sizes.
	membership.acs.org /S/SERM2004/info/Chromatog.html (1154 words)

	High Pressure Liquid Chromatography
		Chromatography involves the separation of mixtures into their individual components by passing a fluid along or through a stationary phase.
		Liquid chromatography is a method using two phases, solid and liquid, in contact with one another.
		Inject these unknown samples into the HPLC to obtain peak area data to determine the concentration of caffeine in the samples.
	tonga.usip.edu /bentzley/expt9hplc.htm (694 words)

	Microdialysis (Site not responding. Last check: 2007-09-10)
		The non-polar end has a high affinity for the column while the polar end has a high affinity for the amine group of the dopamine molecule.
		The electrode is not under pressure in contrast to coulometric analysis.
		The mobile phase flows through a coulometric electrode rather than across it, at pressure, and the electrode itself is a glassy carbon rod with many small pores, greatly increasing the surface area exposed to the mobile phase.
	www.cmbn.rutgers.edu /faculty/abercromdocs/dialysis.htm (1621 words)

	Separation of enantiomeric ephedrine and pseudoephedrine--high pressure liquid chromatography and capillary ...
		Separation of enantiomeric ephedrine and pseudoephedrine--high pressure liquid chromatography and capillary electrophoresis
		Present in high concentrations, these compounds have reportedly caused false identification of methamphetamine in urine specimens.
		High pressure liquid chromatography (HPLC) and capillary electrophoresis (CE) methods were evaluated and compared for their application in analyzing the enantiomeric compositions of these two compounds.
	www.astm.org /JOURNALS/FORENSIC/PAGES/3165.htm (521 words)

	Vitamin tests Encyclopedia of Medicine - Find Articles
		In HPLC, the sample is pumped at high pressure through a tube lined with an absorbent material, to which the different molecules cling at different rates.
		Following separation or purification by HPLC, the vitamin is detected by a color reaction or fluorescence reaction.
		In these reactions, the amount of color or fluorescence that is formed is proportional to the amount of vitamin in the sample, allowing the analyst to calculate the amount of vitamin present in the original sample.
	www.findarticles.com /p/articles/mi_g2601/is_0014/ai_2601001461 (795 words)

	MBAA TQ - Determination of beer flavor compounds by high pressure liquid chromatography. part iv: nucleotides. (Site not responding. Last check: 2007-09-10)
		MBAA TQ - Determination of beer flavor compounds by high pressure liquid chromatography.
		Determination of beer flavor compounds by high pressure liquid chromatography.
		An improved high pressure liquid chromatographic method and different preparative procedures allow a faster and simpler determination of low volatile compounds in beer.
	www.mbaa.com /techquarterly/Abstracts/1975/tq75ab14.htm (117 words)

	Rhys International Ltd, High Pressure Liquid Chromatography, HPLC, Clarity Software (Site not responding. Last check: 2007-09-10)
		The role of enzymes in has expanded; the application of HPLC and enzymes has extended to more disciplines; advances in separation techniques and instrumentation have increased the capability of HPLC; and the discovery of new enzymes has spawned new methods of analysis, more...
		Adept Series HPLC systems and modules offer top grade performance, are economically priced and designed for all applications including method development, quality assurance, quality control, pharmaceutical and ion chromatography, more...
		Clarity is an advanced chromatography station designed to acquire and evaluate data from up to four chromatographs at a time, more...
	www.rhysinternational.co.uk /Medical-Scientific-Equipment/hplc (350 words)

	HPLC : high performance liquid chromatography - High Pressure Liquid Chromatography
		Novasep offers a large range of LC columns and systems, available for medium and high pressure applications.
		Continuous chromatography involves the simultaneous use of several columns.
		The columns, rated at up to 300 bar (4,350 psi) are designed to prevent damage to the packing material at the high SFC operating pressures.
	www.novasep.com /high_performance_liquid_chromatography.asp (149 words)

	Accela High Speed LC-Thermo Scientific
		Accela is designed to optimize performance of sub-two micron particle columns, providing seamless operation spanning conventional LC pressures from short LC columns, up to 15,000 psi for long-column separations of complex bio mixtures.
		This quaternary pump is capable of handling pressures up to 15,000 psi with a delay volume of only 65 µL, enabling high speed chromatographic separations.
		The Accela Autosampler has a specialized diamond coated high pressure valve that can handle the rigors of constant high pressure injections while the unique sampling design enables 30 second injection cycles.
	www.thermo.com /com/cda/product/detail/1,,10123436,00.html (337 words)

	Peak Tek Chromatography Service Specialists
		We are qualified, dedicated professionals in the service and maintenance of all liquid chromatography systems.
		We also specialize in high temperature gel permeation chromatography (GPC) systems, polymers and prep systems and large scale separation for pharmaceutical, chemical, health care and biotech firms throughout the country.
		US We can recommend modifications and changes to your high pressure liquid chromatography (HPLC) equipment which will enable you to optimize your equipment investment.
	www.peaktekhplc.com /EquipmentRepairs (127 words)

	Jim Scarletta - PREP HPLC Project History Page
		Although the company did have several bench-top commercial HPLC units, there was a need for a larger scale design with more flexibility for a specific chemical manufacturing process.
		In chemistry terms: "Liquid chromatographic separation of multicomponent systems according to different interactions of the dissolved components with the stationary phase; mobile and stationary phase can be varied in a wide range to fit the separation properties of the multicomponent mixture.
		The "sifter" for an HPLC is a metal column filled with a very pure, sand-like material (typically silica gel).
	home.pacbell.net /jscarlet/resume/project_prep_hplc.html (676 words)

	Counter Current Chromatography Counter-Current Chromatography Countercurrent Chromatography Quattro CCC Flash ...
		Entry into counter current chromatography with a low-cost QuikPrep™, as a precursor to future expansion into pilot or process preparation, has no financial penalty, but it does have considerable benefits.
		AECS-QuikPrep™ novel sequential liquid – liquid and solid – liquid preparative strategies now fully integrate our flash and HPLC preparative chromatography with HSCCC, to bring potentially massive cost savings in laboratory, pilot and process preparative chromatography.
		To summarise, one of the pair of immiscible, biphasic liquids is immobilised in a planetary centrifuge of a Quattro CCC™ design, and the other flows over this, periodically mixing with and separating from the stationary liquid
	www.ccc4labprep.com (652 words)

	ASTA Analytical Methods - Method 21.1 High Pressure Liquid Chromatography (HPLC)
		High pressure liquid chromatograph, pump flow rate (0.6 to 1.8 ml/min).
		Cap and place on hot plate at 60 C or water bath for three hours, swirling occasionally.
		Fill sample loop and elute with a mix* of: 48.4% methanol, 30.2% HPLC grade water, 13.3% dioxane, 7.9% acetonitrile, 0.2% of 2% perchloric acid.
	www.zarc.com /english/cap-stun/tech_info/oc/hplc.html (292 words)

	Validation of a Multiwell {gamma}-Counter for Measuring High-Pressure Liquid Chromatography Metabolite Profiles -- ...
		Validation of a Multiwell {gamma}-Counter for Measuring High-Pressure Liquid Chromatography Metabolite Profiles -- Greuter et al.
		(HPLC) and with radioactive fractions being measured in a multiwell
		Shown is the mean cpm for 55 repeated measurements together with the SD corresponding with each measurement.
	tech.snmjournals.org /cgi/content/full/32/1/28 (1454 words)

	HIGH PRESSURE LIQUID CHROMATOGRAPHY AND MASS SPECTROMETRY CHARACTERIZATION OF THE NEPHROTOXIC BIOTRANSFORMATION ...
		by HPLC and MS were identical to those used to treat the cells.
		HPLC elution profiles of cisplatin incubated for 30 min with GSH, Cys-Gly, or NAC.
		Bernareggi A, Torti L, Facino RM, Carini M, Depta G, Casetta B, Farrell N, Spadacini S, Ceserani R, and Tognella S (1995) Characterization of cisplatin-glutathione adducts by liquid chromatography-mass spectrometry: evidence for their formation in vitro but not in vivo after concomitant administration of cisplatin and glutathione to rats and cancer patients.
	dmd.aspetjournals.org /cgi/content/full/31/6/705 (3887 words)

	HPLC
		MDS Sciex sells and markets its High Pressure Liquid Chromatography (HPLC) products through a joint venture partnership with Applied Biosystems, one of the world’s leading analytical instrumentation and life sciences company.
		The Tempo nano LC system gives you high performance, reliable, nano-scale liquid chromatography for proteomic applications.
		The Tempo ht LC system is a high throughput liquid chromatography system for applications such as metabolomics and drug discovery.
	www.mdssciex.com /products/instruments/hplc/default.asp?s=1 (142 words)

	High Performance Liquid Chromatography Training (HPLC) - Jasco
		JASCO HPLC training courses will help you to be really confident that your system is working reliably and delivering the right results.
		At the end of one of our one or two day service sessions you will be confident to perform diagnostics and front-line user service.
		If you opt for basic or advanced HPLC training you will develop a real understanding of HPLC and how you can best use it in your laboratory.
	www.jasco.co.uk /HPLC_training.asp (163 words)

	Reagents for Chromatography : Market Research Report
		Since the biotechnology industry is changing rapidly and there are newer methods for chromatography; there is an increased usage of reagents.
		The key objective is to present a comprehensive analysis of the current market and its future direction-a direction that gives an economic drift of 2% to 3% every year for a company's sales.
		There are a number of reagents being used globally for a great deal of chemical analysis but chromatography is the most accepted technique for determining the compounds, their separation and finding out their potency.
	www.marketresearch.com /map/prod/854939.html (2596 words)

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