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Lab. quiz chromatography
Chromatography practical discussion
Chromatography practical discussion
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Chromatography is the laboratory technique for separating mixtures into their components for analyzing, identifying, purifying or quantifying the mixtures or components. The mixture dissolved in the mobile phase (gas or liquid) is passed through the stationary phase (liquid or solid), which separates the analyte from the other molecules in the mixture. The differences in the migration rate of the compounds in these two phases effects the separation.
Chromatography is either preparative or analytical. Preparative chromatography is a form of purification because the components separated from the mixture are for further use. On the other hand, the purpose of Analytical chromatography is done normally is for measuring the relative proportions of analytes in a mixture. It is done using smaller amount of materials.
Body:
Column Chromatography:
Column Chromatography is an adsorption type of chromatography. The separation depends on the adsorption to the stationary phase. Here, the stationary phase is a solid material and the mobile phase is the liquid. It is used for purifying liquids and solids. In this technique, the stationary bed is embedded within the tube. The mixture of mobile phase and the sample that has to be separated are entered through the top of the column. The components in the mixture move with different rates. The substances with lower adsorption towards the stationary phase travel quickly and eluted out first while the substances with greater adsorption travel slowly and eluted out at the end.
Rate of movement is determined by the R.F value:
Retention Factor:
It is the ratio of distance travelled by solute and the distance moved by solvent.
Planar Chromatography:
Planar chromatography is a technique using the st...
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...h the help of the second buffer which increases the ionic strength of the solution. The charge of the buffer can also be modified to alter the rate of interaction between proteins and the resin. If the proteins are negatively charged at our corresponding given P.H, we should use anion exchange chromatography and if it is positively charged, we should use cation exchange chromatography.
Size Exclusion Chromatography
Size Exclusion Chromatography is the separation technique which depends on the molecular size of the components present in the mixture. The molecules are separated due to their different rate of moving out through the pores of the packed material when they pass through the bed of porous particles. The principle of size exclusion chromatography is the non-adsorptive behavior of the sample, which increases the retention of the molecules under analysis.
For this experiment we have to use physical methods to separate the reaction mixture from the liquid. The physical methods that were used are filtration and evaporation. Filtration is the separation of a solid from a liquid by passing the liquid through a porous material, such as filter paper. Evaporation is when you place the residue and the damp filter paper into a drying oven to draw moisture from it by heating it and leaving only the dry solid portion behind (Lab Guide pg. 33.).
The objective of this experiment was to perform extraction. This is a separation and purification technique, based on different solubility of compounds in immiscible solvent mixtures. Extraction is conducted by shaking the solution with the solvent, until two layers are formed. One layer can then be separated from the other. If the separation does not happen in one try, multiple attempts may be needed.
Cu (aq) + 2NO3 (aq) + 2Na+ (aq) + 2OH- (aq) → Cu(OH)2 (s) + 2Na+ (aq) + 2NO3(aq)
Extraction separates compounds based on their solubility. A separatory funnel allows two distinct layers (aqueous and organic) to form when two immiscible liquids are separated with the more dense liquid on bottom. In this lab, dichloromethane (organic) has a density of 1.33g/mL while water (aqueous) has the density of 1.00g/mL, so dichloromethane will be on the bottom and since “like dissolves like” and eugenol does not dissolve in water but dissolves in dichloromethane, eugenol will be found in the dichloromethane layer.
To undertake titration and colorimetry to determine the concentration of solutions By carrying out titrations and colorimetry, the aim of this investigations was to use these methods such that the concentrations of different solutions used can be identified, and to help find the concentration of the unknown solution that were given. Using Titration and colorimetry the concentrations of different solutions in general can be determined and this helps to identify solutions with unknown concentrations. In this assignment I was asked to carry out two different scientific techniques and find the concentration of different solutions.
Physical separation methods refer to any means of olefin/paraffin separation that use the physical properties between the species in order to achieve separation. These properties include size, shape, boiling point, vapour pressure, volatility etc.
Chromatography has been developed over the past century and has an important contribution in many areas of modern science. However the main original work of M.S.Tswett was published in a book Chromatographic Adsorption Analysis.
As explained by Saferstein “Chromatography is a means of separating and tentatively identifying the components of a mixtur... ... middle of paper ... ... ively place the suspect or perpetrator behind bars. Analyzing soil compounds can be measured by the levels of organic molecules including n-alkanes, fatty alcohols and fatty acids, which are all found in the waxy outer layer of plant matter (Geddes, 2008). It basically states that compounds can remain in the soil for thousands of years, which explains that each area being tested has its unique organic profile.
The extraction procedure isolates the pigments in spinach that will be used in the TLC analysis by leaving the insoluble properties behind. Each step serves a purpose in doing so, for example, the spinach is blended into a puree in order facilitate the centrifuge process. 75/25 hexane/acetone solution is used in the blending process because hexane alone is not enough and acetone alone is miscible in water. Anhydrous sodium sulfate is used to dry the organic solution after it has been through the centrifuge tube and separated into a test tube. The purpose of the alumina column is to filter unwanted inorganic chemicals while letting the desired organic chemicals to pass through.
Stationary phase is of extreme importance in an HPLC analysis, as the chemical nature of the same and its compatibility with the analyte of interest is extremely significant for efficient separation. The most commonly used stationary phase is silica packed column which acts as a adsorbent. Each component in the sample interacts with these silica particles and gets eluted out in different time intervals. These silica columns may be of C14 or C18 type depending on the component of interest and also the columns themselves come in various dimensions each with a specific purpose of analysis.
Additionally, chromatography can be used to test the purity of a compound. If a sample is run with several solvent systems, and there is only spot each time, the sample is probably pure. Additionally, TLC can be used to identify an unknown molecule. If an unknown and know are run with several different solvent systems, and have the Rf every time, they are probably identical. Rf stands for retention factor and is equal to the distance the spot travels divided by the distance the solvent travels.
HPLC is based off Column Liquid Chromatography and involves a number of components: a HPLC column, mobile phase and stationary phase (O’Hanlon Cohrt, 2014). The HPLC column
Filtration is used to separate a solid from a liquid. The heterogeneous mixture would be poured through a funnel that would have filter paper folded in it as seen in Figure 1, and that would then be attached to a container to catch the liquid. The solid would get caught by the filter paper, but the liquid would not, resulting in them separating (Decoste, 2008). Decantation is used when a solid and a liquid are together, and the liquid can easily be poured off. Magnetic separation is used to separate a metallic substance from a non metallic substance. In this experiment, iron was separated from sand and salt by using a magnet to pull it out. This technique only works if there is one metallic substance in the mixture (PS Dept.,
A research opportunity like one offered through the Biosystems Dynamics Summer Institute will not only immensely improves on my research skills as a young scientist but would also help improve my ability to work with other fellow scientist as a team focusing on a project. This ability is undeniable one of the most important skill a scientist/researcher needs. In addition, a research opportunity like this will help me make informed decision about my future area of research and allow me to learn practical and technical skills, which could be use in my future area of study as well as other disciplines. Lastly, as an prospective medical school student, a research like this will undoubtedly help me find my passion in the area of research that will most likely interest me. After developing an immense passion for science from middle through high school, it came to me at no surprise my decision to study biochemistry as an undergraduate here at Lehigh University with
Biochemistry, often called biological chemistry, is the process of understanding chemical processes occurring within and relating to living organisms. By monitoring data flow through biochemical signaling and the current of chemical energy through metabolism, biochemical procedures give rise to the intricacy of life. Over the last 40 years, biochemistry has become so effective at explaining living processes that now almost all parts of the life sciences from botany to medicine are involved in biochemical research. Today, the main emphasis of pure biochemistry is in understanding how biological molecules give rise to the developments that occur within living cells, which in turn relates largely to the study and understanding of complete organisms.