Separation & Isolation of Constituents PDF

Separation & isolation of the constituents Dr:Thukaa Z. Abdul-jalil Lec 7 Different methods may be used in this matter ex: 1.Sublimation : which is sometimes used on the whole drug , as in the isolation of caffeine from tea , or for the purification of materials present in a crude extract. 2.Distill...

Separation & isolation of the constituents Dr:Thukaa Z. Abdul-jalil Lec 7 Different methods may be used in this matter ex: 1.Sublimation : which is sometimes used on the whole drug , as in the isolation of caffeine from tea , or for the purification of materials present in a crude extract. 2.Distillation : fractional distillation has been traditionally used for the separation of the components of volatile mixtures , mainly components of volatile oils. 3.Fractional liberation : some groups of compounds may be separated by fractional liberation from a mixture ex: when a mixture of alkaloid bases is shaken with NaOH solution the phenolic alkaloids will be separated as salts. 4.Fractional crystallization : the method exploits the differences in solubility of the components of a mixture in a particular solvent. 5.Chromatography: This process means a variety of separation technique.The sample mixture are distributed between two phases one of which remains stationary while the other phase percolates through or over the surface of the fixed phase. The movement of the mobile common feature of these technique is that the components of the phase results in a differential migration of the sample components. Or chromatography involves the distribution of a compound between two phases , a moving (mobile) phase that is passed over an immobile (stationary) phase. Separation is based on the characteristic way in which compounds distribute themselves between these two phases. What is chromatography? Chromatography is a technique for separating mixtures into their components in order to analyze, purify , and /or quantify the mixture or components. Or separation of a mixture by distribution of its components between a mobile and stationary phase over time. Chromatography terms: Analyte: is the substances to be separated during chromatography. Called solute ,sample Stationary phase: is the phase which tries to fix the analyte in it's place during the chromatography procedure.Retarded the movement of sample to be separated.Called column ,adsorbent ,bed, opposing force, retardation force. Mobile phase: is the phase which moves in a definite direction or is the solvent that will carry the analyte. Called developing solvent , eluent. Developing: How the mobile phase can cause separation? Or the direction of separation. example ascending ,descending, horizontal Chromatographic system : the whole conditions of chromatography example temperature, stationary phase, mobile phase, methods of detection, mechanism of separation…….etc. Methods of detection 1.Physical detection 2.Chemical detection 3.Biological detection 4.Radioactive detection mechanism of separation: the ways in which analytes distribute themselves between two phases.[ stationary phase, mobile phase] Chromatogram: is the visual output of the Chromatograph or the results of the separation procedure. The first detailed description of chromatography is credited by Michael Tswett a Russian biochemist who separated chlorophyll from a mixture of plant pigments in 1906. The stationary phase can be either solid or liquid & the mobile phase can be either a liquid or gas thus several combinations are possible. The two combinations which are not possible are the gas-gas & the solid-solid. Types of chromatography Mobile phase Stationary phase Abbreviation Liquid Solid LSC Gas Solid GSC Liquid Liquid LLC Gas Liquid GLC LSC & GSC are usually adsorption chromatography while in LLC & GLC are partition chromatography. There are several ways to carry out a chromatographic process depending on how the sample is introduced & moved through the stationary phase.