...In this lab, the use of gas chromatography was used to separate a mixture of components. These components then underwent infrared spectroscopy in order to identify their identity. For this lab, the unknown mixture had the code 130-O. This unknown was identified as t-butyl alcohol and cyclopentanone. These compounds were isolated by using the GC and determining when to change vials. The determination of when to change vials came when the first peak began to level of at the bottom. This was around 1.5 according to the GC screen. A source of error in this lab comes from the lack of a GC graph. Not acquiring a print out of the curve from the GC, causes inaccurate analysis of the data. A print out would have given the precise area of each curve...
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...Distillation and Gas Chromatography Goal: The goal of today’s experiment is to collect three different fractions for each distillation by separating two different volatile solutions. Once the fractions are collected, we will record the boiling point range and perform a gas chromatography an original mixture along with the three different fractions that were collected. Significance: This lab is very important if someone needs to separate two different volatile solutions. They can do the simple and fractional distillation, and then using the gas chromatography and compare with other people. This lab basically just teaches you how to separate solutions. During the separation process, there are some factors that must be taken in account, such as: vapor pressure, how polar is our compound, what our temperature for the column is and how long the column is. 1 Theory:...
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...The first of these methods was loss of weight.1 This method, although widely used at the time of its inception, was not the most accurate or effective. This type of analysis was not very involved but had its drawbacks. These included using too much sample, approximately one to two grams, the lack of specifics in the results, and the fact that the atmosphere could alter the results. This is where gas chromatography and micro-solid phase extraction remedied the issue. Although gas chromatography (GS) and solid-phase microextraction (SPME) were not the first types of separation and analytical determinants for identifying and removing residual solvents, they are extremely more accurate and effective compared to the methods that preceded...
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...CLC204 – Analytic Chemistry Experiment Quantitative Analysis of an Unknown Liquid Sample Objective: To be familiar with Ultra Violet Spectrophotometer (UV) and Gas Chromatography (GC) used in chemical analysis UV Abstract In this report, people who consumed tom yum soup suffered from nausea and vomiting due to copper poisoning which was found to leach from a pot into the soup under high heat and acidic condition. It was also suspected that an organic compound was present in the soup which enhanced the absorption of copper in consumer. Hence, as an analytical chemist, we have to use UV to determine the actual concentration of copper standards and blank using external calibration standards. The result of the test solution was measured by comparing it with the calibration of copper. Introduction The goal of this experiment is to obtain the concentration of copper in a known solution. Therefore, in this experiment, we will be using UV to measure the absorbance of the solution. A spectrophotometer is used to measure the amount of light that a sample absorbs. Ultraviolet (UV) light is an electromagnetic radiation with a wavelength in the range of 10nm to 400nm and energy from 3eV to 124Ev. With a shorter wavelength as compared to visible light, UV light is able to penetrate more readily through obstacles. Its name came from a spectrum which humans identify as the colour violet. UV light is invisible, but it can be seen indirectly when it makes other substances...
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...the tube, while low-density substances rise to the top.[1] There are 3 types of centrifuge designed for different applications. Industrial scale centrifuges are commonly used in manufacturing and waste processing to sediment suspended solids, or to separate immiscible liquids. An example is the cream separator found in dairies. Very high speed centrifuges and ultracentrifuges able to provide very high accelerations can separate fine particles down to the nano-scale, and molecules of different masses. Large centrifuges are used to simulate high gravity or acceleration environments (for example, high-G training for test pilots). Medium-sized centrifuges are used in washing machines and at some swimming pools to wring water out of fabrics. Gas centrifuges are used for isotope separation, such as to enrich nuclear fuelfor fissile isotopes. From: https://en.wikipedia.org/wiki/Centrifuge Advantages • can get small particles out of a solution as long as they are not dissociated. Disadvantage • cannot seperate things that have been dissociated, and the fact that you have to know how fast to centrifuge things and how long it will take to get things into the pellet. Centrifuges usually are not used to seperate solids, and I'm fairly sure its...
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...CHROMATOGRAPHY Chromatography (from Greek word Chroma means “color” and Graphein means “to write”) is the collective term used for the separation of the mixture. The mixture is dissolved in a fluid called the mobile phase, which carries it to another material known as the stationary phase. The separation is based on the speed of different constituents of the mixture and on the differential partition of the mobile and the stationary phase (web link7). Distribution or partition coefficient is the basis of chromatography which describes a way in which constituents of a mixture distributes between two immiscible phases. For two such phases A and B, the value for this coefficient is a constant at a given temperature and is given by the expression (36): Kd = Concentration in phase A Concentration in phase B COLUMN CHROMATOGRAPHY For separations of solid and liquids, column chromatography is one of the most important techniques. It is a solid liquid separation technique in which the stationary phase is solid and the mobile phase is liquid. It is based on the principle of differential adsorption of the substance by adsorbent (web link 8). The stationary phase is packed into a glass or metal column and mixture of analytes are then applied, the mobile phase (eluent) is passed through the column either by use of a pumping system or applied gas pressure. The stationary phase is either coated onto discrete small particles (the matrix)...
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...David O. Johnston David Lipscomb College I II The Methclnolysir of Acetal A chemical kinetics a n d g a r chromatography experiment Nashville, Tennessee The methanolysis of acetal and gas chromatography complement perfectly to provide a rare and interesting experiment for the physical chemistry student. The reaction of acetal with methanol is a consecutive reaction in which diethyl acetal (aretal) replaces its two ethoxy groups with methoxy groups forming methy1et)hylacetal first and dimethyl acetal in the second step. Investigating the reaction kinetics for this type of reaction mas almost impossible before the advent of gas chromatography (I). There are many advantages to using the methanolysis of acetal in this study: Sufficient data for a complete analysis can be collected within three hours. The reaction requires reagents which are readily available in high purity. The reactants, intermediate, and products are liquids at temperatures easily accessible for kinetic runs. The primary reactant, intermediate, and product are sepe rated rleanly on a typical gas chromatographic column. The peak heights are linear with concentration in the range studied (2). Analysis of the data affords an application of firshorder kin~ticsand the steady state hypothesis. The experiment presented herc is an adaptation of the detailed study of the reaction by Juvet and Chiu (2), who have shown it to be acid catalyzed and first order in diethyl acetal and methylethyl acetal. By decreasing...
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...------------------------------------------------- Gas chromatography Gas chromatography (GC), is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined). In some situations, GC may help in identifying a compound. In preparative chromatography, GC can be used to prepare pure compounds from a mixture.[1][2] In gas chromatography, the mobile phase (or "moving phase") is a carrier gas, usually an inert gas such as helium or an unreactive gas such as nitrogen. The stationary phase is a microscopic layer of liquid or polymer on an inert solidsupport, inside a piece of glass or metal tubing called a column (a homage to the fractionating column used in distillation). The instrument used to perform gas chromatography is called a gas chromatograph (or "aerograph", "gas separator"). The gaseous compounds being analyzed interact with the walls of the column, which is coated with a stationary phase. This causes each compound to elute at a different time, known as the retention time of the compound. The comparison of retention times is what gives GC its analytical usefulness. Gas chromatography is in principle similar to column chromatography (as well as other forms of chromatography, such as HPLC, TLC), but has several notable...
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...mm i.d.) were cryofocused at the head of a capillary column prior to a GC/MS analysis. The desorption temperature was set at a point about 20 degrees C higher than the melting point of each sample individually, and held for 3 min. The analytical results using 7 different pharmaceuticals were in agreement with those obtained by direct injection (DI) of the solution, followed by USP XXIII. This proposed TD-GC/MS method was demonstrated to be very useful for the identification and quantification of residual solvents. Furthermore, this method was simple, allowed rapid analysis and gave good repeatability. 2 J Pharm Biomed Anal. 2011 Jan 25;54(2):417-21. doi: 10.1016/j.jpba.2010.09.006. Epub 2010 Sep 15. A general static-headspace gas chromatographic method for determination of residual benzene in oral liquid pharmaceutical products. Liu H, Tang Q, Markovich RJ, Rustum AM. Source Global Quality Services-Analytical Sciences, Merck & Co., Inc., Union, NJ 07083, USA. hui.liu2@merck.com Abstract Sodium benzoate is used in oral liquid pharmaceutical products for its anti-microbial properties. The benzoate salts present in...
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...Pesticides In Water Using Chromatography And Mass Spectrometry An Abstract of a Thesis Presented to the Faculty of Chemistry Department Western Illinois University In Partial Fulfillment of the Requirements for the Degree Master of Science By Prashanth Goud Kunuru September 2013 This thesis follows the style and format of the Journal of Analytical Chemistry ABSTRACT Pesticides are chemicals, artificial or natural substances, used for pest control. They have negative influence on human health when accumulated in the body. Numerous studies have clearly linked pesticides exposures to various diseases including cancer and Parkinson’s disease. Water bodies often serve as a key receiver of harmful pollutants emitted from industrial and domestic sources. Pesticides can often enter water through sewage plants, sewer overflows, surface water runoffs, and leaching from agricultural applications or even through improper disposal. Regulatory issues and public concerns over pesticide residues in water supplies have been increasing, and it is important to develop a reliable method for routine test of pesticides in water supplies. Presented here is a novel solid phase extraction technique using disposable pipette extraction (DPX) followed by chromatography and mass spectrometry analysis for determination of pesticides in water. The purpose of the current study was to evaluate the suitability of high pressure liquid chromatography with UV detector (HPLC/UV)...
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...224 G. M. WARNOCK AND J. DUCKWVORH 1944 are not used as a source of minerals to sustain the mammary supply during lactation. In other words, an osteoporotic skeleton is not an obligatory consequence of lactation in this species at least. Considerable difficulties exist in the determination of these requirements by the metabolic balance technique, since this method does not indicate when mobilization of minerals from the spongiosa is accompanied by mobilization from the shaft. Further, the balance over a whole lactation is often small in relation to the total quantities of materials analyzed and may be close to the analytical errors of the methods when the diet given is rich in minerals. The present observations may find some application in the determination of certain mineral requirements of lactation. Because the losses of Ca and P are unavoidable, involving the gradual liberation of reserves laid down at an earlier peripd, it has been difficult to estimate the requirements for lactation on the bafsis ofthe negative values obtained by the balance technique. Since the present study shows that, in the rat, it is possible to restrict the withdrawal of bone salt to the spongiosa, leaving the shaft unaffected, it seems reasonable to suggest that lactation requirements could be defined as those intakes which, for a given output of minerals in milk, will restrict the withdrawals to the spongiosa. Thus, using a similar technique, the problem ofthe mineral requirements for lactation...
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...Types of Chromatography Adsorption Chromatography Adsorption chromatography is probably one of the oldest types of chromatography around. It utilizes a mobile liquid or gaseous phase that is adsorbed onto the surface of a stationary solid phase. The equilibriation between the mobile and stationary phase accounts for the separation of different solutes. Partition Chromatography This form of chromatography is based on a thin film formed on the surface of a solid support by a liquid stationary phase. Solute equilibriates between the mobile phase and the stationary liquid. Ion Exchange Chromatography In this type of chromatography, the use of a resin (the stationary solid phase) is used to covalently attach anions or cations onto it. Solute ions of the opposite charge in the mobile liquid phase are attracted to the resin by electrostatic forces. Molecular Exclusion Chromatography Also known as gel permeation or gel filtration, this type of chromatography lacks an attractive interaction between the stationary phase and solute. The liquid or gaseous phase passes through a porous gel which separates the molecules according to its size. The pores are normally small and exclude the larger solute molecules, but allows smaller molecules to enter the gel, causing them to flow through a larger volume. This causes the larger molecules to pass through the column at a faster rate than the smaller ones. Affinity Chromatography This is the most selective type of chromatography employed...
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...This experiment will separate the components of a mixture on the basis of their differing absorptive tendencies on a stationary phase, which is the method of chromatography. The mobile phase will consist of four distinct transition metal cations dissolved in an acetone-hydrochloric acid eluent, along with three unknown solutions; the identities of these will be determined based on a comparison of the Rf value of these to the known cations. First to be prepared was the stationary phase, or chromatographic paper, which in this case was filter paper. Given only large sheets, it was cut into a rectangle with 20 cm length and 10 cm width. Before cutting, though gloves were put on so that skin oil would not stain the filter paper. Also, the filter paper was not laid on the lab table, but on a paper towel. With a pencil, a line was drawn 2 cm from the bottom edge of the paper. Marks were put on the line, 2 cm apart, and labeled with the appropriate cations and the unknowns labeled as U1, U2, and U3. The stationary phases were then spotted with the corresponding knowns and unknowns, then dried under a heat lamp. This spotting process was repeated 3 times. It was done using glass capillary tubes; these used adhesive and cohesive forces to draw up the cation solutions into the tube and subsequently released them onto the filter paper when touch. With the stationary prepared, the developing chamber was made. In a 600-ml beaker 9 ml of acetone and 1ml of 6 M HCl were combined (under...
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...Ethnopharmacology and natural product drug discovery remains a noteworthy hope in the current discovery of new drugs. Many modern drugs have origin in traditional medicine and ethnopharmacology. Ethnopharmacology is the use of tradition plant medicines as source of new drugs. Traditional Indian Medicine - Ayurveda has a long history and is one of the great living traditions. Considerable research on pharmacognosy, chemistry, pharmacology and clinical therapeutics has been carried out on Ayurvedic medicinal plants. Several preclinical and clinical studies have examined cytoprotective, immunomodulatory and immunoadjuvant potential of Ayurvedic medicines. The ethnopharmacology knowledge, is holistic and systems approach supported by experiential base can serve as an innovative and powerful discovery engine for newer, safer and affordable medicines. The Process of Modern Drug Discovery using Ethnopharmacology The first stage should be the reported use of a natural occurring material for some purpose which can be related to a medicinal use. There must be an indication of a genuine effect and therefore, the material needs to be identified and characterized. It can be collected for test studies which comprises tests for relevant biological activity linked with isolation and structure determination of any chemical present that might be responsible. The active compounds are discovered by fractionation of the extract linked with testing for activity of each fraction until pure compounds...
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...Bulk Polymerization of Styrene Bulk polymerization of styrene will be conducted with different initial initiator concentrations. The polymers will be analyzed for their MW and PDI by size exclusion chromatography (SEC) using a calibration curve. The MW dependence on conversion will be investigated. The effect of the initiator concentration on polymer MW will be examined. Materials. Azobisisobutyronitrile (AIBN) and toluene (HPLC) were purchased from Sigma-Aldrich and used as received. Styrene (Sigma-Aldrich) was purified by passing through a silica column to remove inhibitors. CDCl3 was purchased from Cambridge Isotope and was used as received. Methods. Reaction procedure. To a vial charged with freshly purified styrene (10 g) was AIBN (0.7g, 0.35g or 0.17g) added at room temperature. The mixtures are then heated at 80˚C in an oil bath. Seven aliquots of the reaction mixture are removed at fixed time intervals (e.g., 0, 20, 40, 60, 80,100 min, 1 week) and analyzed by 1H NMR spectroscopy for conversion and SEC for polymer MW and PDI. Sample preparation for SEC analysis. An aliquot of the reaction mixture (3mg) is dissolved in THF(1mL) and was filtered through a syringe membrane filter prior to injection into SEC column. Sample preparation for 1H NMR analysis. An aliquot of the reaction mixture (0.1-0.5 mg) is dissolved in CDCl3 (1mL) and is transferred into a NMR tube for conversion analysis. Lab report write-up. Summarize and discuss your experimental...
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