Abstract This paper looks at chromatography, an analytical technique based on the principle of selective adsorption that is used for the chemical separation of mixtures and substances. It examines how it is an important field of chemistry, which deals with the separation of pure substances from complex mixtures, and is widely used in the analysis of foods, drugs, blood, petroleum products, and radioactive-fission products. It also examines how variants of "column" chromatography have been developed since its discovery in 1906, including partition, liquid, paper, thin-layer, and gas-liquid chromatography.
From the Paper "Chromatography was discovered in 1906 by the Russian botanist Mikhail Tswett who first coined the term (derived from the Latin for "color writing"). The technique used by Tswett for separating the pigments (chlorophyll) of plants consisted of pouring petroleum-ether extract of green leaves over a column of powdered calcium carbonate in a vertical glass tube. As the solution seeped through the column the individual components of the mixture moved downward at different rates of speed, and the column became marked with horizontal bands of colors. Tswett did not enjoy a happy relationship with fellow scientists of his time, as they derided his results, and his technique, with Tswett responding in kind. As a result, it wasn?t until the 1930s that his methods were accepted as a breakthrough in chromatography."
Abstract The paper explains that gel filtration chromatography utilizes the physical properties of molecular size and shape to attain a separation of proteins. A table that summarizes the properties of several gel filtration media and a graph that estimates the extracted proteins' molecular weights are presented and the paper describes the experiment where separate solutions of protein standards and extracts were subjected to gel filtration chromatography. The chromatographic set-up and the applications of gel filtration chromatography are also discussed.
Outline:
Abstract
Discussion of Data and Results
From the Paper "Chromatography is a separation method that takes advantage of the relative rates at which chemical substances in a mobile phase are retained on a stationary phase. Classification of the various chromatographic techniques are based on factors including state of retaining material, nature of retaining force and mobile phase, method of termination and solute introduction, and presence or absence of gradients [1]."
Gel filtration chromatography, also known as gel permeation, gel filtration, molecular sieve or molecular exclusion chromatography, utilizes the physical properties of molecular size and shape to attain separation. In this method, the stationary phase consists of inert gel bead particles with small pores of controlled size and porosity [2]."
Abstract This paper presents an experiment in which two types of chromatography were used to separate a mixture of two dyes, methylene blue and fluorescein. The materials and methods that were used for the experiment are discusses as well as the results that were obtained. The results are presented in a table form.
Table of Contents:
Introduction
Materials and Methods
Results
Discussion
Additional Experiments
Appendix
From the Paper "Gel permeation chromatography is a type of size exclusion chromatography (SEC), where the mobile phase is an organic solvent and separation occurs based on size. (Davies, Johnson, 2007). It is used to determine the molecular weights of organic and biological molecules, such as nucleic acids and proteins. The stationary phase is a gel medium, (e.g. agarose, polyacrylamide, or dextran) and elution occurs under low pressure. The molecules of interest are often further separated based on charge, acidity/bascitiy and affinity to particular molecules. This technique is efficient because all the samples can be simultaneously loaded without deterring the elution process, or disrupting the biologically-active state of the different samples. (Davies, Johnson, 2007)."
From the Paper "Although the properties of supercritical fluids were know, it was not until 1958 when Lovelock suggested that a supercritical fluid can be used as a mobile phase in chromatography. Now, supercritical fluid chromatography (SFC) is widely used in extraction, fraction, and chromatography. SFC has many advantages over other chromatography methods. It allows one to separate many substances that cannot be analyzed by gas chromatography. Its applicability is limited by volatility and thermal properties of many organic compounds. Although less volatile compounds can be analyzed by high performance liquid chromatography, very long analysis time and very small column diameters are needed in order to achieve good separations due to the limitations of solute diffusion in the mobile phase. SFC is able to overcome these difficulties and allows high-resolution separation at low temperatures with short analysis times."
Abstract This paper explains that nature acts as a pharmacy, offering us products, from the forest pharmacy and the pharmacy below water, with which we can heal ourselves: For example, aspirin, quinine, cyclosporins, and penicillin. This paper details the techniques that are available to researchers, to collect samples of natural products from the wild in a systematic manner, to extract compounds from these samples, to isolate the biologically-active compounds within these extracts, to characterize the biologically-active compounds chemically in terms of their structure, to evaluate the biologically-active compounds biologically, to determine potentially useful therapeutic effects and finally the methodology necessary to take these compounds to clinical trial. The author stresses the importance of finding new and more effective drugs to fight against bacterial infections and cancer. Outline.
Table of Contents
Introduction
Nature's Pharmacopeia.
The Isolation of Biologically-Active Compounds and their Extraction Identification: Techniques
Introduction
Chemical Extraction
Biological Evaluation
Chemical Analysis
Chromatography Solid Phase Extraction
Paper Chromatography Thin Layer Chromatography Flash Chromatography High Performance Liquid Chromatography Central Counter Current Chromatography Determining the Chemical Structure of Compounds Isolated by Chromatography Nuclear Magnetic Resonance
Mass Spectrometry
Drug Development
Examples of the Isolation and Identification
An Example of Extraction, Isolation and Chemical Characterization of Biologically-Active Compounds from Larch Wood
Biologically-active Compounds from Marine Organisms
What Compounds Have Been Isolated From Marine Organisms?
Biologically-Active Anti-Cancer Compounds ? Testing for Human Safety
Conclusion
From the Paper "Chromatography is the process whereby two or more compounds or ions are separated through the distribution of the compound or ion between two phases, one that is mobile and the other which is stationary. These two phases can be of any combination: liquid-liquid, solid-solid, solid-liquid or gas-liquid, gas-gas, or gas-solid. There are many specific techniques for chromatography, some of which will be described below, and all follow the same basic principles. All forms of chromatography involve a rapid and dynamic equilibrium of molecules between the two phases, either free ? mobile - or absorbed ? stationary. Molecules will constantly move back and forth between the free and absorbed states, with millions of molecules absorbing and desorbing every second. The equilibrium between these states depends on three factors: the polarity and size of the molecule, the polarity of the stationary phase, and the polarity of the solvent. Thus, three different variables can be changed in chromatography, which can change the equilibrium between the stationary and mobile phases: this allows one to choose mobile and stationary phases that will separate just about any combination of compounds."
From the Paper "Gas chromatography is a method for the separation and analysis of complex mixtures of volatile organic and inorganic compounds (1:666). Most compounds with boiling points less than 250oC (480oF) can be analyzed using this technique. This paper will describe the apparatus used for gas chromatography, the principles on which it works, how a thermal conductivity detector works in gas chromatography, and whether or not it can be used with a sample of potassium t-butoxide.
General Principles of Gas Chromatography
There are two types of gas chromatography: gas-liquid chromatography, where the sorbent is a nonvolatile liquid called the stationary liquid phase, coated as a thin layer on an inert, granular solid support; and gas-solid chromatography, where the sorbent is a granular solid of large surface area (1:666). The..."
Abstract This paper examines how, prior to modern medicine and the advent of forensic toxicological sciences, death from intentional poisoning was often indistinguishable from natural causes and how, consequently, poisoning with toxic substances was a preferred form of murder throughout human history until relatively recently. It looks at how modern toxicology consists of several distinct scientific specialties: Descriptive, mechanical, and regulatory. It discusses how forensic toxicologists examine blood and other fluids extracted from victims of crimes, as well as organs and other viscera removed from cadavers.
From the Paper "As the pharmaceutical and chemical industries grew, many more toxic
substances became available to those who would use them for nefarious purposes. These synthetic alkaloids required an entirely different method of identification, such as paper chromatography, based on separation of substances based on their respective molecular size and other chemical properties such as polarity, introduced in the middle of the twentieth century. The final conceptual and technological advance that marked the modern era of forensic toxicology was the subsequent development of gas chromatography and spectrometry , which enable the very precise identification of thousands of different toxic compounds and an accurate measurement of their exact concentrations within organic tissues."
Abstract The paper begins by purifying beef heart and ends with a highly-quantitative analysis of the results of attempting to isolate the enzyme lactate dehydrogenase. It contains every aspect of a detailed biochemistry lab report. The paper contains complex quantitative analysis with supporting statistics. It also has scanned photographs of the gel electrophoresis.
From the Paper "Lactate dehydrogenase (LDH) is a crucial enzyme that regulates lactate levels throughout the mammalian body. Proper LDH function is essential for a number of important biochemical pathways, including the Cori Cycle and glycolysis among others. Without it, the glycolytic cycle would come to a halt due to diminished nicotinamide adenine dinucleotide (NAD+) reserves, and the buildup of lactate would ultimately result in lactic acidosis-a potentially fatal affliction."
Abstract This paper looks at the techniques used by a forensic toxicologists, particularly when looking for drugs in the body postmortem. It looks at what factors have to be considered which change drug levels after death. The paper also looks at how blood alcohol levels are tested when drunk driving is suspected.
From the Paper "Forensic toxicology is a specialty area of analytical chemistry. Forensic Toxicology is the science of the adverse effects of chemicals on living organisms and a toxicologist detects and identifies foreign chemicals in the body in particular toxic or hazardous substances. Forensic toxicologist usually receive samples for analysis as preserved samples of body fluids stomach contents and body parts. They have access to coroner's reports which will give them any signs and symptoms and postmortem data that may be helpful. Because most substances entering the body are changed..."
