Detectors used in UV spectophotometry
- 1. DETECTORS USED IN GAS CHROMATOGRAPHY PRESENTED BY: NIMMI ROY 1ST YEAR MPHARM DEPT OF PHARMACEUTICS SCP , VALACHIL 1
- 2. CONTENTS тАв Introduction тАв Instrumentation тАв Detectors тАУ Definition тАУ Ideal characters тАУ Type of detectors тАУ Thermal conductivity detector тАУ Flame ionization detector тАУ Nitrogen phosphorous detector тАУ Flame photometric detector тАУ Electron capture detector тАУ Atomic emission detector тАв References 2
- 3. Gas chromatography: тАв Introduction: It is process of separating components(s) from the given crude drug by using a gaseous mobile phase . It is mainly used for the separation of thermally stable and volatile organic and inorganic compounds. Two types: 1.GSC- Mobile phase is gas and stationary phase is soild adsorbent. 2.GLC- Mobile phase is gas and stationary phase is non-volatile liquid bound to solid support. 3
- 4. Instrumentation тАв Six basic components 1. Carrier gas 2. Sample injection system 3. Thermostated chamber 4. The separation column 5. One or more detectors 6. An amplification and recorder system 4
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- 6. DETECTORS The detector which is situated at the exit of the separating column , is to sense and measure the small amount of separated components present in the carrier gas stream leaving the column. The output of the detector is fed to a device which produces a trace called chromatogram. The choice of the detector which depends upon factors such as: a) Concentration level to be determined b) The nature of the separated components 6
- 7. Ideal characters of detector 1. Adequate sensitivity. 2. Good stability and reproducibility. 3. A linear response to solutes. 4. A temperature range from room temperature to at least 400┬░C. 5. A short response time that is independent of flow rate. 6. Similarity in response towards all solutes. 7. Non destructive of sample. 8. It should respond to wide variety of compound. 7
- 8. Type of detector: тАвBased on specificity: яГШNon specific i. Thermal conductivity detector ii. Atomic emission detector iii. Photo ionization detector яГШ Specific i. Flame ionization detector ii. Flame photometry iii. Nitrogen phosphorous detector iv. Electron capture detector v. Nitrogen chemiluminescence detector тАвBased on destructivity: яГШDestructive i. Flame ionization detector ii. Nitrogen phosphorus detector iii. Photo ionization detector iv. Nitrogen chemiluminescence detector яГШ Non destructive i. Thermal conductivity detector ii. Electron capture detector 8
- 9. Thermal conductivity detector тАв It is also called as Katharometer or Hot wire detector. тАв It works on the principle of Wheatstone bridge. 9
- 10. Application: яГШThese are having large temperature co-efficient of resistance and corrosion resistance. яГШThermistors are used for some trace elements The following figure which shows the wheatstone bridge: 10
- 11. Flame ionization detector: тАв The FID was invented by scientist Harley and Pretorius and separated by MCWilliams and Dewer. тАв It makes the use of an oven , wherein a flame is produced burning hydrogen gas in presence of oxygen of air. Fig:1 Fig:2 11
- 12. Nitrogen phosphorous detector тАв A nitrogen phosphorus detector is a relatively simple modification to the interior of FID , it may be made much more sensitive to either nitrogen or phosphorus containing compounds. 12
- 13. Flame photometric detector тАв A third generation type of flame detector is flame photometric detector , also based on standard FID. тАв It is selective towards compound containing Sulphur and phosphorous 13
- 14. Electron capture detector тАв It responds to only those compounds whose molecules have an affinity for electrons. тАв Eg: chlorinated compound, unsaturated compound etc.ry ve тАв On the other side , it responds very little to compounds such as hydrocarbons. 14
- 15. Atomic emission detector тАвThe strength of the detector lies in its ability to simultaneously determining elements. тАвIt uses microwave energy to excite molecules. тАвThis emits radiation which breaks down molecules to atoms such as , S , N , P , Hg , etc 15
- 16. References 1.Skoog, west.et.al. тАЬfundamentals of analytical chemistryтАЭ,8th edition , page no.950 2.Sharma B.K,тАЭ Instrumental methods of analysisтАЭ, 6th edition , page no.128 16
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