FLAME EMISSION SPECTROSCOPY

FES is the one of the emission spectroscopy

1. Flame emission spectroscopy Presented by K.Gopalasatheeskumar I M.Pharm ., Pharmacology

2. CONTENTS INTRODUCTION HISTORY PRINCIPLE INSTRUMENTATION APPLICATIONS INTERFERENCES 9/22/2017 KMCH College of Pharmacy 2

3. INTRODUCTION Flame emission spectroscopy is so named because of the use of a flame to provide the energy of excitation to atoms introduced into the flame . 9/22/2017 KMCH College of Pharmacy 3

4. HISTORY Early- detect the presence of metal elements in samples aspirated into a flame. Modern analytical FES- Lundegardh - 1934 , (flame- air-acetylene, Prism spectrograph, densitometer for spectral line ) First "flame photometer" -1945- Barnes.(Na, K detection, Poor detection of Ca , Mg)-Meeker burner 1948- total-consumption burner. 9/22/2017 KMCH College of Pharmacy 4

5. PRINCIPLE 9/22/2017 KMCH College of Pharmacy 5

6. Desolvation : The metal particles in the flame are dehydrated by the flame and hence the solvent is evaporated Vapourisation : The metal particles in the sample are dehydrated. This also led to the evaporation of the solvent. Atomization : Reduction of metal ions in the solvent to metal atoms by the flame heat. Excitation : The electrostatic force of attraction between the electrons and nucleus of the atom helps them to absorb a particular amount of energy. The atoms then jump to the exited energy state. Emission process: Since the higher energy state is unstable the atoms jump back to the stable low energy state with the emission of energy in the form of radiation of characteristic wavelength, which is measured by the photo detector. 9/22/2017 KMCH College of Pharmacy 6

7. The basic components for flame photometer are as follows Burner(source) Atomizer Monochromators Detector Read out device INSTRUMENTATION 9/22/2017 KMCH College of Pharmacy 7

8. BURNERS The FLAME used in the flame photometer should possess following functions: The flame should have ability to evaporate the liquid droplets from the sample solution in the formation of solid residue The flame should decompose the compounds in the solid residue resulting in the formation of atoms. The flame must have the capacity to excite the atoms formed and cause them to emit radiant energy. 9/22/2017 KMCH College of Pharmacy 8

9. FLMES IN FES Name of the element Emitted wavelength range (nm) Observed colour of the flame Potassium (K) 766 Violet Lithium (Li) 670 Red Calcium ( Ca ) 622 Orange Sodium (Na) 589 Yellow Barium (Ba) 554 Lime green 9/22/2017 KMCH College of Pharmacy 9

10. TYPES OF BURNERS Mecker Burner Total Consumption Burner Laminar Flow (premix) Burner Lundergraph Burner. Shielded Burner Nitrous Oxide – Acytelene Flame. 9/22/2017 KMCH College of Pharmacy 10

11. MECKER BURNER 11 This burner employed natural gas and oxygen. Produces relatively low temp. and low excitation energies. This are best used for ALKALI metals only. Nowadays it is not used. 9/22/2017 KMCH College of Pharmacy

12. Total consumption burner 12 In this burner the fuel and oxidant are hydrogen and oxygen gas respectively. In this the sample solution is aspirated through a capillary by the high pressure. fuel and oxidant are burnt at the tip of the burner. The name “total consumption burner” is used because all the sample that enters the capillary will enter the flame regardless of the droplet size. 9/22/2017 KMCH College of Pharmacy

13. Advantage Design is simple and entire sample is consumed. Disadvantage Uniform and homogeneous flame is not obtained. Since droplet size vary, leading to fluctuations in the flame intensity. 13 9/22/2017 KMCH College of Pharmacy

14. 14 LAMINAR FLOW BURNER 9/22/2017 KMCH College of Pharmacy

15. LAMINAR FLOW (PREMIX) BURNER. In this type of the burner, aspirated sample, fuel and oxidant are thoroughly mixed before reaching the burner opening and then entering the flame. Important feature of this is that only a small portion (about 5%) of the sample reaches the flame in the form of small droplets and is easily decompose. ADVANTAGES: Premix burner is non-turbulent ,noiseless and stable. Easy decomposition which leads to high atomization. Can handle solution up to several % without clogging. DEMERITS When it contains 2 solvents, the more vol. will evaporate and lesser will remain undissociated . 9/22/2017 KMCH College of Pharmacy 15

16. MONOCHROMATORS AND FILTERS In simple flame photometers, the monochromators is the prism. QUARTZ is the material most commonly used for making prisms because quartz is transparent over entire region . FILTERS: the filter is made up of such material which is transparent over a narrow spectral range. When a filter is kept between the flame detector, the radiation of the desired wavelength from the flame will be entering the detector and be measured. The remaining undesired wavelength will be absorbed by the filter and not measured . In flame photometry, the wavelength as well as intensity of radiation emitted by the element has to be monitored. Hence a filter or monochromatore is used. 9/22/2017 KMCH College of Pharmacy 16

17. DETECTORS P hotovoltic cell Phototubes photomultiplier tubes. 9/22/2017 KMCH College of Pharmacy 17

18. APPLICATIONS FES has found wide application in agricultural and environmental analysis, industrial analyses of ferrous metals and alloys as well as glasses and ceramic materials, and clinical analyses of body fluids. FES can be easily automated to handle a large number of samples. Array detectors interfaced to a microcomputer system permit simultaneous analyses of several elements in a single sample They are also used to determine the metals present in Chemicals, Soil, Cements, Plant materials, Water, Air pollutants and Oceanography 9/22/2017 KMCH College of Pharmacy 18

19. INTERFERENCES Matrix interference Chemical interference Ionization interference Spectral Interferences 9/22/2017 KMCH College of Pharmacy 19

20. Matrix interference When a sample is more viscous or has different surface tension than the standard it can result in differences in sample uptake rate due to changes in nebulization efficiency. Such interferences are minimized by matching as closely as possible the matrix composition of standard and sample. 9/22/2017 KMCH College of Pharmacy 20

21. Chemical interference If a sample contains a species which forms a thermally stable compound with the analyte that is not completely decomposed by the energy available in the flame then chemical interference exists . Refractory elements (Ti , W, Zr , Mo and Al) may combine with oxygen to form thermally stable oxides. Analysis of such elements can be carried out at higher flame temperatures using nitrous oxide – acetylene flame instead of air-acetylene to provide higher dissociation energy. Alternately an excess of another element or compound can be added e.g. Ca in presence of phosphate produces stable calcium phosphate which reduces absorption due to Ca ion. If an excess of lanthanum is added it forms a thermally stable compound with phosphate and calcium absorption is not affected. 9/22/2017 KMCH College of Pharmacy 21

22. Ionization interference Ionization interference is more common in hot flames. The dissociation process does not stop at formation of ground state atoms. Excess energy of the flame can lead to excitation of ground state atoms to ionic state by loss of electrons thereby resulting in depletion of ground state atoms. In cooler flames such interference is encountered with easily ionized elements such as alkali metals and alkaline earths. Ionisation interference is eliminated by adding an excess of an element which is easily ionized thereby creating a large number of free electrons in the flame and suppressing ionization of the analyte . Salts of such elements as K, Rb and Cs are commonly used as ionization suppressants. 9/22/2017 KMCH College of Pharmacy 22

23. THANK YOU 9/22/2017 KMCH College of Pharmacy 23