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Analysis Practical

1. ESTIMATION OF QUININE SULPHATE BY FLUORESCENCE SPECTROSCOPY First Semester 2020-2021 Masters of Pharmacy in Pharmaceutical Chemistry Reg No:- 201862320110011 of 2020-21 Roll No:- 18620120002 Guru Nanak Institute Of Pharmaceutical Science And Technology

2. AIM: To estimate Quinine Sulphate by Fluoroescence Spectroscopy.

3. THEORY Fluorescence: It is caused by the absorption of radiant energy & the re-emission of some of this energy in the form of light, when there is transition from singlet excited state to singlet ground state . Phosphorescence: At favourable conditions like low temperature & absence of oxygen , there is transition from excited singlet state to triplet state which is called a inter system crossing . The emission of radition when electrons undergo transition from triplet state to singlet ground state is called as Phosphorescence. FIG 1. FLUORESCENCE& PHOSPHORESCENCE Fluorescence Spectrometry is a fast, simple & inexpensive method to determine the concentration of an analyte in solution based on its fluorescent properties . In Fluorescence Spectroscopy, a beam with a wavelength varying between 180 to 800 nm passes through a solution in a cuvette . Then, measurement from an angle the light that is emitted by the sample.

4. In Fluorescence Spectrometry, there is a measurement of both an excitation spectrum (the light that is absorbed by the sample) & an emission spectrum ( the light emitted by the sample) This is done by means of the quantum yield , which is defined as the fraction of the incident radiation which is re-emitted as fluorescence. The concentration of the analyte is directly proportional with the intensity of the emission . When recording an emission spectrum, the intensity is dependent on: Excitation of wavelength Concentration of the anylte solvent Path length of the cuvette Self-absorption of the sample  Factors effecting Fluorescence Intensity: Conjugation Nature of substituent groups Rigidity of structure Effect of temperature Viscosity Oxygen Effect of pH Photochemical Decomposition

5. WORKING PRINCIPLES OF FLUORESCENCE: Only a relatively small number of compounds can fluorescence By adding a fluorescent label, some non-fluorescent compounds can be made fluorescent. In general, molecules that show fluorescence have one or more aromatic groups in its structure. A molecule can be excited from its electronic ground state In the electronic ground state, the molecule has the lowest possible electronic energy. Upon excitation (the absorption of a photon) one of the electrons goes into a higher electronic state and the molecule is excited. The molecule will stay in its electronic excited state in the order of pico or nanoseconds Then the electron will fall back to its ground state & will emit a photon of a longer wavelength than the photon used for excitation. In this experiment, the fluorescence mission of Quinine Sulfate in aqueous solution will be studied as a function of pH. Once there is an establishment of necessary pH for maximum fluorescence intensity, a calibration curve will be prepared using a series of standard solutions. The Quinine content of a commercial preparation will then be determined.

6. INSTRUMENTATION: Source of light : There are four types, Mercury Vapour Lamp : - Produce intense line spectrum above 350nm . High pressure lamps gives lines at 366,405, 436, 546,577,691,734nm . Low pressure lamps give additional radiation at 254nm . Xenon Arc Lamp: - Spectrum is continuous over the range between over 250- 600nm , peak intensity about 470nm . Tungsten Lamp: - Intensity of the lamp is low. If excitation is done in the visible region this lamp is used . Tunable Dye Lasers : - Pulsed nitrogen laser as the primary source. Radiation in the range between 360 and 650 nm is produced. Condensing Lens Filters & Monochromators : In inexpensive filter fluorimeter two filters are presnt , Primary filter -absorbs visible light & transmits uv light. Secondary filter -absorbs uv radiations & transmits visible light. In spectrofluorimeter two mpnochromators are presnt , which have Gratings. Excitation monochromaters - isolates only the radiation which is absorbed by the molecule. Emission monochromaters - isolates only the radiation emitted by the molecule. Sample cells & sample holder : Cylindrical or Polyhedral (Quadrangular) cells fabricated of silica or colour corrected fussed glass. Path length is usually 10mm or 1cm. It need not be made up of quartz, since we are measuring only the emitted radiation not the absorbed radiation. All the surfaces of the sample holder are polished in fluorimetry , because emission measurements are made at 90◦ angle. Detectors: Photovoltaic cell Photo tube Photomultiplier tubes – Best and accurate. Galvanometer: For output measurement.  

7. TYPES OF INSTRUMENTS : Single beam (filter) fluorimeter Double beam (filter) fluorimeter Spectrofluorimeter Double Beam) WORKING OF INSTRUMENTS : The light from a mercury- vapour lamp (or other source of ultraviolet light) is passed through a condensing lens, a primary filter (to permit the light band required for excitation to pass), a sample container, a secondary filter (selected to absorb the primary radiant energy but transmit the fluorescent radiation), a receiving photocell placed in a position at right angles to the incident beam (in order that it may not be affected by the primary radiation), and a sensitive galvanometer or other device for measuring the output of the photocell. FIG 2.ESSENTIAL PARTS OF A SIMPLE FLUORIMETER  

8. REQUIREMENTS: Dilute sulphuric acid, (0.1N):- Add 3 ml of concentrated sulphuric acid to 100 ml of distilled water & dilute to one liter in a volumetric flask. Stock solution of quinine:- Weigh out accurately 0.100 g quinine and dissolve it in 1 L 0.1N Sulphuric acid in a graduated flask. Calculate the Quinine concentration in mg/L Ammonium Acetate Solution (10% w/v) :- Dissolve 50 gm in 500 ml of distilled water.  

9. PROCEDURE Preparation of Standard Quinine Solution: Weigh accurately 100 mg of Quinine Sulphate powdered drug. Dissolve in 100 ml of 0.1 N H 2 SO 4 (1mg/ml) Take 10 ml of above solution & dilute to 100 ml with 0.1 N H 2 SO 4 (100µg/ml) Again,Take 10 ml of above solution & dilute to 100 ml with 0.1 N H 2 SO 4 (10µg/ml) To get the resulting solution of 0.5,1.0,1.5,2.0, & 2.5 µg/ml concentrations, take 0.5, 1.0,1.5, 2.0 & 2.5 ml of above solutions respectively & dilute to 10 ml with 0.1 N H 2 SO 4 Preparation of Sample Solution Pipette out 1 ml of given unknown sample solution & make up the volume to 10 ml with 0.1 N H 2 SO 4 . Switch on the instrument, set the excitation & emission filters at the wavelength 365 nm to 459 nm respectively. Set the fluorescence intensity to 0% by using 0.1 N H 2 SO 4 as blank & 100% by using highest concentration of the standard solution (2.5µg/ml) Repeat the same atleast for two times more to minimize the instrumental error Measure the percentage fluorescence intensity of different standard & sample solutions Plot a graph between concentration vs FI & determine the concentration of unknown sample by expolating the found FI.

10. Observation table: Plot a graph between concentration & %FI From graph the contration of unknown solution is found to be …….. Since the sample solution dilutes by 10 times, so the concentration of Quinine Sulphate is found to be……. Sr. No Concentration %FI 1 2 0.5 3 1.0 4 1.5 5 2.0 6 2.5 7 Unknown

11. RESULT: The concentration of given sample of Quinine Sulphate found to be …………. By fluorimetry . CONCLUSION: Fuorescence spectroscopy is a very sensitive & selective analytical technique, giving it a major advantage over absorption spectroscopy when used in the detection & measurement of trace amounts of organic compounds. This assay method can br utilized for estimation of trace amount of quinine in different organic samples & compounds .