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Edit Comment Close Premium member Presentation Transcript PowerPoint Presentation: Refractometry By Goutami Perala JNTUH A seminar presentation onFlow of Presentation: Flow of Presentation 1. Principle 5.Latest models of Refractometers 7. Conclusion 8. References 2. Factors affecting RI measurement 3. Instrumentation 4. Operating Bausch and lomb abbe’s ref 6. ApplicationsPowerPoint Presentation: What is Refractometry ? Measurement of refractive index of unknown substance. measure substances dissolved in water and certain oils.PowerPoint Presentation: Principle Measurement of RI of unknown substance by measuring angle of refraction made when the substance is brought into contact with the medium (prism) of a known refractive indexRefractive index : : Refractive index :PowerPoint Presentation: RI of unknown substance can be determined without measuring velocities if : RI of the prism is known The angle of incidence and angle of refraction are known. Indicated as :PowerPoint Presentation: Critical ray Grazing incidence Critical angle of refraction Critical boundaryPowerPoint Presentation: Used for Characterization of liquid samples(identity of a sample ) Assess the purity of a sample by comparing its refractive index to the value for the pure substance. Determine the concentration of a solute in a solution by comparing the solution's refractive index to a standard curve.Factors affecting RI measurement: Factors affecting RI measurement Temperature of the liquid Inverse relation For organic liquids RI decreases by approximately 0.00045 ± 0.0001 for every 1 °C increase in temperature AND -0.0001 for water Thermometer and water cooling system provision Temperature dependence of refractive index for selected substances Substance Isopropanol 1.3802 1.3772 1.3749 Acetone 1.3616 1.3588 1.3560 Ethyl Acetate 1.3747 1.3742 1.3700 Water 1.3334 1.3330 1.3325PowerPoint Presentation: 2. Wavelength of radiation source - inverse relation - RI of a transparent medium decreases with increase in wavelength – dispersion - monochromatic light should be used - shorter wavelengths are refracted more than the longerPowerPoint Presentation: Instrumentation 2 types of instruments Refractometers - abbe’s refractometer - pulfrich refractometer - immersion/dipping refractometer Interferometers (differential refractometer) - deflection refractometer - reflection refractometerAbbe’s Refractometer: Abbe’s Refractometer Principle and block diagaram - Light refraction through liquids to determine the amount of dissolved solids in liquids by passing light through a sample and showing the refracted angle on a scale. -RI of the prism should be greater than that of the sample The Brix scale Brix scale is defined as: the number of grams of pure cane sugar dissolved in 100 grams of pure water (grams sugar/100 grams H 2 O ). Block diagramAmici prisms or compensating prisms: Amici prisms or compensating prisms To prevent the chromatic aberration Light sources in abbe’s refractometer : -natural light - C - line of hydrogen lamp(653.6nm) - D - line of sodium vapor lamp(589.3nm) - F - line of hydrogen lamp(486.1nm) - G – line of mercury vapor lamp(435.8nm)Pulfrich Refractometer: Pulfrich Refractometer Principle and block diagaram Right angled prism attached to a small glass block containing the sample light is incident at grazing incidence(at right angle) Angle of refraction is measured with the help of telescope n = RI of sample = RI of glass blockImmersion/dipping refractometer: Immersion/dipping refractometer Principle and block diagaram Similar to abbes but lacks illuminating prism lower surface of the refracting prism dipped into the sample solution Grazing incidence of light onto the prism Critical ray detected by the fixed telescope and RI is calculatedPowerPoint Presentation: Interferometers Differential refractometers Measure reflection or deflection of the light beam to give differential RI Suitable when RI of the solute is different from that of the solvent Advantages - reproducible results - act as detectors in HPLC - useful in gel permeation chromatographyDeflection refractometer: Deflection refractometer Principle Tungsten lamp source Collimation by slit and lens Light onto the double prism with sample and reference Deflection in the sample compartment is recorded Advantages - requires small sample - direct relationship between deflection and the concentrationReflection refractometer : Reflection refractometer Principle: Fresnel’s law of reflection: The light reflected at a glass-liquid interface is proportional to the RI of the sample and the angle of incidence AnimationAbbe’s refractometer(Baush & Lomb): Abbe’s refractometer ( Baush & Lomb) Right viewPowerPoint Presentation: Left viewPowerPoint Presentation: Operating the Bausch & Lomb Abbe-3L Refractometer: Open the prism assembly and remove the tissue.PowerPoint Presentation: Use a pipette to apply your liquid sample to the prism.PowerPoint Presentation: Be careful not to let the glass pipet tip touch the prism since this may scratch the soft prism glass.PowerPoint Presentation: Close the prism assembly.PowerPoint Presentation: Turn on the lamp using the switch on the left side.PowerPoint Presentation: Adjust the lamp so the light shines on the prism .PowerPoint Presentation: Look through the eyepiece.PowerPoint Presentation: If you are close to the index of refraction of your sample you should see that the view in the eyepiece shows a dark region on the bottom and a lighter region on the top.PowerPoint Presentation: If you do not see a light and a dark region, turn the handwheel on the right side of the instrument until you do.PowerPoint Presentation: Before making the final adjustment, it will usually be necessary to adjust the lamp position and to sharpen the borderline between the light and the dark regions using the compensator dial on the front of the refractometer .PowerPoint Presentation: Once you have a crisp demarcation between the light and dark regions, turn the handwheel on the right hand side to place the borderline exactly on the center of the crosshairs as shown.PowerPoint Presentation: To read the index of refraction, depress the switch on the left hand side of the refractometer until you see the scale through the eyepiece. The upper scale indicates the index of refraction. By carefully interpolating you can read the value to 4 decimal place accuracy. The example shown here has a refractive index of 1.4606.PowerPoint Presentation: Record the refractive index. Then read the thermometer and record the temperature.PowerPoint Presentation: clean the refractometer using a tissue and then wash the prism with a little solvent(like ethanol).PowerPoint Presentation: Reporting Results The standard format for reporting the index of refraction is shown below:Analyzing Results : Analyzing Results Finding Refractive Indexes: comparison with the literature to know the identity of the compound or to asses its purity The following sources list refractive indexes for a wide variety of substances: The CRC Handbook of Chemistry and Physics Lange's Handbook of Chemistry The Merck Index Chemical catalogs (e.g., the one from Aldrich Chemical Co. ) MSDS datasheetsLatest Models…: Latest Models… Company: ATCO Maart Product : Digital Refractrometer Model No. : DG-NXT Company: Tanco Ltd Product: Abbe’s Product Code : PLT-288 Company: Nidek – palm Product: Hand held Auto refractor Model name: Nidek palm ARK Video !!PowerPoint Presentation: ApplicationsPowerPoint Presentation: Identitiy and purity Determination of concentration : - by calibration curve method Determination of alcohol percentagePowerPoint Presentation: Food and Beverages EstimationPowerPoint Presentation: Refractometers for Sugar Milling, Refining, Processing Cane sugar milling and refining Beet sugar milling and refining Invert sugar Liquid sugar Confectionary sugar Molasses Brown sugarPowerPoint Presentation: Petroleum Refractometers waxes Fuels Oils LubricantsPowerPoint Presentation: Refractometers for Flavor, Fragrance and Cosmetics Perfumes Skin cleansers Lotions Lemon, lime, orange Palm Creams Waxes Natural oils SandalwoodPowerPoint Presentation: Water Based Petroleum Based Resins Polymers Coolants Gels Glues Glycols Fine chemicals Ethylene Acids Oil based paints Fine chemicals Fluranes PET Polymers Resins Solvents Plastics Chemical IndustryRefractometers for Pharmaceutical and Toxicology Testing: Refractometers for Pharmaceutical and Toxicology Testing Total Parenteral Nutrition (TPN) - QA Tool Toxicology Testing in Urine Sevoflurane EnfluraneProduct Spotlight: The ValiMed System by CDEX: Product Spotlight: The ValiMed System by CDEX Using New Technology to Validate Returned Narcotics in the ORJ57TPN AUTOMATIC HOSPITAL PHARMACY REFRACTOMETER (Refraktometer): J57TPN AUTOMATIC HOSPITAL PHARMACY REFRACTOMETER ( Refraktometer ) Automatic Electronic Temperature Control to detect controlled-substance tampering US FDA Regulation 21 CFR Part 11PowerPoint Presentation: Other Pharmaceutical Applications Refractometry Stops Theft of Controlled Substances Hand-Held refractometers in veterinary laboratory medicine The structure and concentration of solids in photoreceptor cells studied by refractometry and interference microscopy. Quantitative estimation of urinary protein excretion by refractometry .PowerPoint Presentation: Cntd….. Refractometry and Interferometry of Living Cells Measurement of colostrum quality in dairy cattlePowerPoint Presentation: Conclusion Refractometry is a simple and easy technique to identify and assess the purity of many compounds including pharmaceuticals it also has some demerits like…… Lack of precision due to the temperature effect. Lack of sensitivity and selectivity in case of digital refractometers . It requires skilled personnel. Despite these demerits, refractometry is still widely being used to identify many pharmaceutical compounds.PowerPoint Presentation: References vogel’s text book of quantitative chemical analysis Gurudeep chatwaalPowerPoint Presentation: http://www2.ups.edu/faculty/hanson/labtechniques/refractometry/intro.htm http://proscitech.com.au/cataloguex/get_notes.asp?refract http://www.refractometer.pl/ http://www.rudolphresearch.com WebsitesPowerPoint Presentation: THANK Y OU You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.