TRAVISTRA

 SCANNING ELECTRON MICROSCOPE It is used for the surface characterization of materials. It produces images of a sample by scanning the surface with a focused beam of electrons. It provides information about topography(surface features), morphology (shape and size), composition, and crystallographic information. PRINCIPLE The electrons interact with the atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample.  The accelerated electrons in an SEM carry significant amounts of kinetic energy, and this energy is dissipated as a variety of signals produced by electron sample interactions. Backscatter electrons are incidental electrons reflected backward which provide composition data related to element and compound detection. Diffracted backscatter electrons determine crystalline structures as well as the orientation of minerals and micro-fabric, X-rays emitted from beneath the sample surface, can provide ele...

 GAS CHROMATOGRAPHY It is used for the separation as well as analysis of gaseous mixture and volatile organic compounds. Principle The components of a mixture are separated depending upon the extent of adsorption or partition of the stationary phase and at the rate at which the component is carried out by the mobile phase.  The mobile phase is a gas like Argon, Nitrogen, Helium, or hydrogen. The stationary phase may be solid or liquid. If the stationary phase consists of a solid material like silica, alumina, then chromatography is termed as Gas Solid Chromatography (GSC), and if the stationary phase is a liquid held as a thin layer on a solid support, then the technique is known as Gas-Liquid Chromatography (GLC)GSC- adsorption. GLC- partition INSTRUMENTATION  Carrier gas: It is allowed to flow through the system, carrying the sample in the vapor state through the column. It should be chemically inert, suitable for the detector employed, it should give the best column pe...

 HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY It is a method used for the separation, purification, and identification of various nonvolatile high molecular weight organic compounds and natural products like cholesterol, terpenoids. ADVANTAGES High-speed separation Excellent column separation Solvent consumption is minimum Sensitive and accurate Separation can be done at an ambient temperature. PRINCIPLE The components of the mixture are separated depending upon the extent of adsorption and partition on the stationary phase and the rate at which the component is carried by the mobile phase. The mobile phase is liquid and the stationary phase can be solid or liquid. INSTRUMENTATION Solvent reservoirs are used to collect the different solvents. Pressure pump to apply pressure  Sample injector to give the mixture which is to be separated in the analytical column Regulator to adjust the flow rate Guard column to remove the particulate matter and contaminants from the solvent. The analyt...

 THIN LAYER CHROMATOGRAPHY It is a chromatographic separation method used to separate mixtures, to check the purity of a mixture, and to monitor the progress of the reaction. Procedure A glass plate coated with a material of the adsorbent will constitute the stationary phase. The material is made into a slurry or a paste and the glass plate is coated with it by a thin layer applicator and dried. This glass plate with a thin layer of stationary phase is called chromatoplate. The mixture to be separated is applied to one end of the plate and it is placed in the solvent. When the solvent reaches near the top, it is removed and dried. If the components are colored the spots can be readily located. If the components are colorless the dried plate is sprayed with a suitable reagent to make the spot colored. In this way, the position of the components is located and their Rf values are determined. Rf value is the ratio of the distance traveled by a component to the distance traveled by the...

 COLUMN CHROMATOGRAPHY It is a technique in which the stationary phase is solid or a liquid supported by a solid. When a column is used as the adsorbent it is called adsorption column chromatography. When the solid column is acting only as a support to the liquid adsorbent then it is called partition column chromatography. SEPARATION The selection of solvent is based on the nature of the components in the mixture. Adsorption depends upon the nature of the solvent and the adsorbent.  The rate at which the components of a mixture are separated depends upon the activity of the adsorbent and the polarity of the solvent. If the activity of the adsorbent is very high and polarity is low, then separation is low but gives good separation. If the activity of the adsorbent is low and the polarity of the solvent is high, then the separation is rapid but gives poor separation PROCEDURE A proper adsorbent is selected and made a slurry with a suitable liquid and placed in a suitable tube wh...