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Identification of amino acids by using paper chromatography

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Introduction

Identification of amino acids by using paper chromatography Aim To separation and identification of amino acids by using paper chromatography Introduction Chromatography is a techniques separation of mixtures It involves passing the sample, a mixture which contains the analyte, in the "mobile phase", often in a stream of solvent, through the "stationary phase." The stationary phase retards the passage of the components of the sample. When components pass through the system at different rates they become separated in time, like runners in a mass-start foot race. Each component has a characteristic time of passage through the system, called a "retention time." Chromatographic separation is achieved when the retention time of the analyte differs from that of other components mixtures in the sample. There are many types chromatography but there are four main types which are Liquid Chromatography Liquid Chromatography this is used in the world to test water samples to look for pollution in lakes and rivers. It is used to analyze metal ions and organic compounds in solutions. Liquid chromatography uses liquids which may incorporate hydrophilic, insoluble molecules also Gas Chromatography Gas Chromatography is used in airports to detect bombs and is used is forensics in many different ways. It is used to analyze fibres on a persons body and also analyze blood found at a crime scene. ...read more.

Middle

Hence, known Rf values can be compared to those of unknown substances to aid in their identifications. (Note: Rf values often depend on the temperature, solvent, and type of paper used in the experiment; the most effective way to identify a compound is to spot known substances next to unknown substances on the same chromatogram.) In addition, the purity of a sample may be estimated from the chromatogram. An impure sample will often develop as two or more spots. Purity of the sample After the chromatography experiment, if a sample develops as only one spot it may or may not be pure. The sample may contain another compound which did not separate under the conditions of the experiment. Purity of samples is often determined in conjunction with other techniques, such as measuring a sample's melting point or recording its nuclear magnetic resonance spectrum Risk assessment In the experiment I made the solvent mixture with ethanol I must be aware that it is highly flammable and when being handle to keep it away from a naked flame also it is harmful to the skin and eyes so you should wear safety spectacles and gloves, also in the solvent in the mixture there will ammonia I must be aware that It is very toxic and if inhaled it could be fatal this is why the solvent must be made in a ...read more.

Conclusion

To avert disaster, always keep the stationary phase covered with the mobile phase! Because the silica or alumina gel that makes up the stationary phase is quite dense, column chromatography tends proceed very slowly if gravity is the only force pulling the mobile phase through the gel. The process can be sped up if high gas pressure at the top of the column or a vacuum at the bottom of the column is used to push or pull the mobile phase more quickly. This method is called flash column chromatography. In your food dye experiment, you will have the option of performing flash column chromatography by using a syringe attached to the bottom of the column to provide vacuum suction and thereby quicken elution. A final note is necessary about the versatility of column chromatography. While most organic chemistry laboratories restrict themselves to the usual silica or alumina stationary phase, this is not the case in biochemical applications. Biochemists have been incredibly creative in adapting the column technique for separating macromolecules. For example, by coating the stationary phase with anionic groups, it is possible to selectively adsorb positively charged sample molecules to the column. Or, in an even more advanced application, a stationary phase of cellulose coated with antibodies against a particular molecule can be used to isolate that molecule from a cell extract. There are few separations that column chromatography can't perform! ?? ?? ?? ?? 1 ...read more.

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