The Separation and Identification of Chemical Compounds - Essay Example

CHEMISTRY Techniques used in the separation and identification of chemical compound and their real world applications Chemical techniques have enabled the food, and pharmaceutical companies to fasten their quality control. In connection to this, these industries have been able to produce more products, hence increasing their production output. Some of these techniques are; High performance liquid chromatography, atomic absorption spectroscopy and Energy dispersive X-ray Fluorescence. The objective of this paper, is therefore to explain how, the three techniques work, how they applied in the industries and their limitations. High Liquid Performance chromatography (HPLC) This is a chemical technique used to identify and quantify various chemical elements in a mixture. In this technique, the sample to be analyzed is passed through an adsorbent. The components of the mixture will interact with it differently, resulting in separation of the elements (Scoog & Holler, 1992). HPLC has a wide range of application, for example it is used in pharmaceutical companies in the separation of vitamin C, and it also applied in the legal profession by detecting illegal substances such as cocaine in the urine (Ballinger et al., 2011). HPLC can be said to be a mass transfer process that involves adsorption. A typical HPLC instrument has a detector, sampler and a pump. The sampler is used to collect the sample, then the pump is used to pass sample through a mobile phase, which mostly consist of an adsorbent such as silica gel. In the mobile phase, the sample mixture will separate because they have different adsorption rates. It is this difference in adsorption rates that HPLC principle relies on. Finally, the detector is used to separate the different components (Kebbekus & Mitra, 1998). Applications of HPLC in the food industries HPLC is one of the most preferred technique in the food industries. It is mostly used in the quality control. HPLC is preferred to other techniques, because it is cheap to maintain and it does not need a very qualified personnel to run it (Ballinger et al., 2011). An example, where HPLC is applied is the sugar cane industries. After sugar cane has been crushed, it is always squeezed to remove the juice. The juice is then treated with chemicals to kill any fungi which is available in it. It is at this stage, where HPLC finds its use. This is because some of the chemicals always remain in the final product. In connection to this, HPLC is always used to determine, if there are any traces of the chemicals in the final sugar. If there are any, it is then taken back for treatment (Scoog &Holler, 1992). Limitations of HPLC The main limitation of this technique is that it cannot be used for very complex chemical elements. In addition, the technique cannot detect very small amounts of elements. Finally, in cases where there is a reversible solvent matrix, it may not be able to identify the chemicals present in the sample (Kebbekus & Mitra, 1998). Atomic Absorption Spectroscopy (AAS) AAS is a technique used to identify, and quantify elements. It has a source of radiation, which is used to excite the elements in the sample. During excitation, the elements will absorb a specific amount of energy, to go to the next electron levels. Hence the name absorption spectroscopy (Ballinger et al., 2011). The amount of radiation that is absorbed by the element, can then be used to identify it. This is done using a set of tables, which has all the data regarding all the elements and the amount of energy that they absorb (Scoog & Holler, 1992). AAS technique has found applications in various sectors .For example, in water analysis, where it is used to determine the amount of dissolved metals. It is also used in clinical analysis, to determine the amount of heavy metals in blood, urine and in food. Finally, it is also used in the pharmaceutical industries to determine, if there is any residue of the enzymes which was used to produce the drug (TM, 2000). AAS instrumentation In order for a sample to be analyzed, it has to be atomized, then a radiation is passed through the sample, after the atoms has been excited the energy released is then passed through a monochromator so as to distinguish the different radiations (TM, 2000). AAS applications AAS is used in many industries as stated above. For example, in the distillation of water. According to many authors, water always contain, dissolved metals, suspended solids and other dissolved elements. In connection to this, many industries prefer using AAS, because it does not require a lot of sample preparation. The only thing, which one has to do is to take the water the way it is, and analyze it. Then, compare it with a reference material to see the chemicals present in the water (Scoog & Holler, 1994). Limitations It is time consuming. This is because only one element concentration can be determine at a time. Finally, it is also expensive to maintain. Energy Dispersive X-ray Fluorescence (EDXRF) This chemical technique uses radiation to identify, and determine, the amount of elements available in solid samples. EDXRF is based on X-ray principle, the instrument uses an X-ray source, to excite the elements in the sample. During this excitation, an electron will be emitted from the sample (TM, 2000). Therefore, a hole will be left in the element. This makes the element unstable because it is full of energy. In order to be became stable, an electron, from a higher energy level electron state will come and feel the hole. This process always results in emission of an x-ray. It is this principle that EDXRF principle is based on (Scoog & Holler, 1994). EDXRF technique, has a wide range of applications. In research institutions, it is used to determine, the chemical elements present in the soil. It is used in food industries for quality control purposes (Kebbekus & Mitra, 1998). Instrumentation It has an X-ray source, a monochromator, sample holders and a detector. The X-ray source is used to produce an X-ray which is used for the excitation. The sample holders are used to hold the sample and the detector is used to detect and identify the emitted radiations (TM, 2000). Applications EDXRF is used in many industrial applications, for example in the pharmaceutical industry. This is because, it is a multi-element analytical tool. Most pharmaceutical industries use EDXRF to analyze, their raw materials before using them for processing (Ballinger et al., 2011). Limitations It is expensive to run and maintain, and it also needs a qualified personnel (TM, 2000). In addition, the instrument cannot be used to analyse elements with lower atomic numbers. References Scoog, D. West, D. & Holler, J. (1992) Fundamentals of Analytical Chemistry. Philadelphia: Saunders College Publishing. Jack T. Ballinger, Gershon, J. Shugar, B. (2011) Chemical Technicians Ready Reference Handbook, Fifth Edition. McGraw-Hill Professional Test Methods: Methods for Organic Chemical Analysis of Municipal and Industrial Wastewater. (2000) U.S. EPA-600/4-82-057. Kebbekus, B. and Mitra, S. (1998) Environmental Chemical Analysis. New York, NY: Chapman & Hall. Read More