Polarimetry and it's Analysis

Introduction,instruments used,applications,advantages & disadvantages of polarimetry.

1. Presented by Rakesh B.Ahuja Guide Prof. K. B.Gabhane VidyaBharati College Of Pharmacy, Amravati-444601 2019-2020 POLARIMETRY

2. INDEX A. Introduction B . Plane Polarised Light C . Optical Activity D . Theory of Optical Activity E . Polarimeter F . Applications

3. INTRODUCTION Polarimetry is one of the important instrumental methods employed in analysis. This measures the rotation of the polarized light as it passes through an optically active compound. This technique involves the measurement of change in the direction of vibration of polarized light when interact with an optically active compound. A substance is said to be optically active if it rotates the plane of the polarized light.

4. PLANE POLARISED LIGHT According to wave theory of light, an ordinary ray light is considered to be vibrating in all planes at right angle to the direction of propagation. If this ordinary ray of light is passed through a Nicol prism, the emergent ray has its vibration only in one plane. This light having wave motion in only one plane is known as Plane Polarised Light. • NICOL Prism – Iceland Spar Calcite ( CaCO3 form ) ( or) Polaroid

5. A plane polarized light which consists of two components of fixed magnitude rotating in opposite directions to one another . • The right circulatory polarized light • The left circulatory polarized light • Plane polarized light is the vector sum of these two components

6. OPTICAL ACTIVITY Definition:-“The property of rotating the plane of polarization of plane-polarized light.” • It Has found that magnitude of rotation depend upon the following factors: 1.Nature of Substance 2.Length of liquid column ( l ) through which light passes. 3.Concentration of the solution. 4.Nature of the solvent. 5.Temperature of the solution (t) 6.Wavelength of the light used.

7. The Rotatory Power of a given solution is generally expressed as specific rotation. It is the number of degress of rotation of plane polarized light produced by one gram of the substance per ml. The measurements is carried out at temp using sodium light. The Specific rotation can be Calculated by the following relation: [α] = specific rotation, T = temperature, λ = wavelength, θ= optical rotation, c = concentration in g/100ml, l = optical path length in dm.

8. Types of molecules analysed by Polarimetry: .Molecule must be Optically active. Optically Active molecule contain asymmetric carbon atom.

9. Theory of Optical Activity An optically active substance is one that rotates the plane of polarized light Example : (1) Lactic acid Dextro= right designated by ‘d’, (+), clockwise Levo= left designated by ‘l’, (-), counterclockwise

10. LEFT IMAGE:- J.B . Biot (1774-1862), who discovered optical activity in liquids and promoted its application in the sugar industry. RIGHT IMAGE:- A simple diagram explaining the operation of a polarimeter. Unpolarized light from a bulb or a flame is made linearly polarized by a polarizer (a Nicol prism until after 1940). The direction of polarization rotates progressively on its way through a tube containing a sugar solution. The angle of rotation is measured by the observer, using a rotatable Nicol prism or a combination of a quartz wedge and a fixed Nicol prism.

11. INSTRUMENTATION Optical activity may be detected & measured by an instrument → Polarimeter

12. Light source – Sodium vapor lamp • Analyzer– another Nicol prism aligned to intercept the linearly polarized ray as it emerges from the sample solution • A polarimeter consists of a polarized Light source – Sodium vapor lamp, Polarizer –quartz prism material and Analyzer – Nicol prism aligned to intercept the linearly polarized ray as it emerges from the sample solution, a graduated circle- to measure the rotation angle, and sample tubes.

13. POLARIMETER

14. APPLICATIONS ^Quantitative application If the specific rotation of sample is known its concentration in the solution can be estimated. ^Qualitative application. Optical activity is the only parameter available for distinguishing between D and L isomeric forms. ^ Saccharimetry important practical application of polarimetry determination of high conc. of sugars visual saccharimeters called POLAROSCOPES

15. Polarimetry is used in many industries Food industries Polarimetry is used in food industries for quality control of original, intermediate, and final products, the determination of concentrations, and purity control. • Sugar industries: sugar (sucrose, levulose, glucose, etc.), sugar syrups, starch, sugar-free sweeteners like isomalt, etc . • Dairy: lactose, sucrose, lactoglobuline, lactic acid, esters, etc. • Vine industries: analysis of sugar on the vine, tartaric acid, esters, etc. • Fruit: analysis of sugar in fruit syrups (levulose), acids and esters (malic acid, etc.), essential oils, etc.

16. Pharmaceutical industries Polarimetry is used in pharmaceutical industries for purity control and determination of concentration of substances according to the requirements of the European and American Pharmacopeia by measurement of both specific and optical rotation. • Alkaloids: cocaine, codeine, nicotine, morphine sulphate, etc. • Amino acids: asparagine, glutamic acid, etc. • Organic compounds: ascorbic acid, menthol, camphor, etc. Others : steroids, antibiotics, serums, vitamins, etc.

17. Medicine • Research of sugar and albumin in urine • Hormone research •Enzymology and toxicology research Cosmetic Industries Control of purity and identification of optically active essential oils and essences like lemon oil, orange oil, lavender oil, spearmint oil, etc.

18. Research applications • Analysis of optically active compound structure analysis • Determination of configuration changes of solved macromolecules • Monitoring changes in concentration of an optically active component in a reaction mixture, as in enzymatic scission • Distinction of optical isomers • Investigating kinetic reactions by measuring optical rotation as a function of time • Analyzing molecular structure by determining optical rotation dispersion

19. CASE STUDY “ Polarimetric Determination of Starch in Raw Materials and Discharged Waste from Beer Production” Abstract. Brewer’s spent grain (BGS) is a by-product of the brewing process, consisting of the solid fraction of barley malt remaining after separation of worth. In this research, raw materials and discharged waste from beer production were evaluated on the basis of starch content, using Ewers polarimetric method. Keywords: starch, polarimeter , optical rotation, malt, brewers’ spent grain, black beer.

20. Introduction. In preparation for brewing, barley is malted in a controlled germination process, which serves to increase the enzymatic content of the grain. During malting, enzymes break down the cell structure of the endosperm, releasing nutrients necessary for yeast growth and making the starch available for enzyme degradation during mashing. Starch, accounting for about 60 to 65% of the malt’s weight, is composed of amylose, which is reduced to maltose and maltotriose and amylopectins that decompose into glucose ( Bamforth , 2003). Brewer’s spent grain (BGS) is a by-product of the brewing process, consisting of the solid residue remaining after mashing and lautering ; it consists primarily of grain husks and other residual compounds not converted to fermentable sugars by the mashing process ( Xiros and Christakopoulos , 2009). BSG is produced in the largest quantity, corresponding to around 85 % of the total generated and it is estimated that about 200 t of wet spent grain with 70 to 80 % water content are produced per 10.000 hl of produced beer ( Kunze , 1996 ).

21. Aims and objectives. Raw materials and discharged waste from beer production were evaluated on the basis of starch content, using Ewers polarimetric method. This method was used because it provides accurate results even in samples which contain proteins, sugars and hemicellulose in high quantities. Materials and methods. All the materials (malt, brewers’ spent grain) were supplied by the microbrewery of the Faculty of Food Science and Technology. The BSG used in this work was obtained from a process employing 100 % malt, without addition of other cereal adjuncts. Caramelized and black malt are added in smaller quantities (5-10 %) to obtain darker colors and to enhance flavor characteristics. The polarimetric determination of starch content is based on the optically activity of starch. Due to the fact, that starch cannot be dissolved in water, hydrochloric acid is used. After dissolution, the sample needs to be clarified, filtrated and measured in a polarimeter . The optical rotation of all samples was measured at 20°C by using a sample cell of 200 mm optical path length. Results are presented as the mean of two replications with standard deviation. Moisture was determined by weight difference before and after heating at 130 ºC for 1.5 h.

22. Results and Discussion . Chemically , BSG is rich in polysaccharides, protein and lignin. Robertson et al., 2010 stated that residual starch can contribute up to 13% of the dry weight and the spent grain from lager malts has higher protein content than that from ale. The starch level present in brewers spent grain was negligible, 5.09±0.08 % due to extensive amylolysis during mashing, compared with the level found in malt (57.78±0.34 %, w/w). A similar value was also reported in studies of Makowska et al., 2013, which identified the grains starch content of 4.56±0.42 %; similar values were also reported, both for malts and brewers spent grain by Waters et al., 2012.

23. Conclusion. Chemical composition of BSG varies according to barley variety, harvest time, malting and mashing condition, type and quality of secondary raw materials and the brewing process. Methods used to determine the starch provides accurate results which are in accordance with values reported in the literature.

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