Instrumental method of chemical analysis

Instrumental method of chemical analysis ,Glass electrode,Single beam Spectrometers, Instrumentation of Gas liquid Chromatography

1. Instrumental Methods Of Chemical Analysis (IMCA) by Pranali Patil

2. Instrumental Methods Vs Non-instrumental Methods MIMP For Theory Exam (5Marks) Advantages ? Disadvantages?

3. Advantages of Instrumental Methods? Disadvantages of Non-instrumental Methods?

4. Points Instrumental Methods Non-instrumental Methods 1 Handling Easy to handle Difficult to handle 2 Result More accurate & reliable Less accurate 3 Time period Requires less time period Comparatively, m ore time period Result Time period

5. About samples? Quantity/ Amount of Sample Wastage of Sample Complex samples Poisonous or carcinogenic samples Coloured, turbid and colloidal samples

6. Points Instrumental Methods Non-instrumental Methods 4 Amount of sample Small quantities of sample ( in micro scale) can be analyzed by this method. Large quantities of sample ( in macro scale) can be analyzed by this method. 5 Wastage of sample Mostly, sample cannot be wasted & sometimes, it can be recovered. Generally, sample can be wasted & it is difficult to recover. 6 Complex samples Generally, complex samples can be analyzed by using this method. Generally, complex samples cannot be analyzed by using this method. 7 Poisonous or carcinogenic samples Poisonous or carcinogenic samples can be analyzed. Poisonous or carcinogenic samples cannot be analyzed. 8 Coloured, turbid and colloidal samples Such solutions can be analyzed by using this method. Such solutions cannot be analyzed by using titration method.

7. About Advanced Technology? Advanced Facilities Uses in qualitative & quantitative methods Monitoring Reactions

8. Points Instrumental Methods Non-instrumental Methods 9 Advanced facilities Most of instruments are now compatible with printer and other devices. So, data can be stored, printed and managed easily. e.g. GCMS Such facilities are not available. 10 Used in qualitative & quantitative methods Generally, it is used for quantitative measurements. Generally, it is used for qualitative method because results obtained are less accurate. 11 Monitoring the reactions It is used to monitor the reactions. e,g , pH meter is used to monitor rate of corrosion by measuring the pH of the medium in which the metal is present. It is not used to monitor the reactions.

9. Advantages of Non-instrumental Methods? Disadvantages of Instrumental Methods?

10. Points Instrumental Methods Non-instrumental Methods 1 Cost It is expensive method because cost of instrument /equipment is high. It is not expensive method because cost of glassware used is low. 2 Special Training Special Training is required to operate the instrument properly. Special Training is not required. 3 Calibration or Standardization Calibration or standardization of the instrument is required before analyzing the samples. e.g. pH-meter is standardized by using buffer solutions. Calibration or standardization is not required. 4 Sensitivity and Accuracy Sensitivity and accuracy depends on the instrument used. Sensitivity and accuracy depends on expert person. Space for Instrument ?

11. Glass Electrode

12. Principle, Construction & Working of Glass Electrode MIMP (6M) Diagram of Glass electrode: (2Mark)

13. The electrochemical cell formed is represented as given below: (1Mark) Principle : (1Mark) Construction : (1Mark) Working: (2Mark)

14. Advantages of Glass electrode: (2POINTS FOR 1M) Glass electrode is very simple to operate. It can be used in portable and therefore extensively used in chemical, industrial, agricultural and biological laboratories. By using glass electrode, accurate results are obtained between pH range 1 to 10. However, by using special glass electrodes, pH up to 14 can be measured. It is not poisoned easily . It is unaffected by oxidation – reduction potentials. The glass electrode can be used to measure pH a) in the presence of strong oxidizing and reducing solutions , b) of coloured , turbid and colloidal solutions. c) of poisonous or carcinogenic samples. Disadvantages / Limitations/ Drawbacks of glass electrode: (2POINTS FOR 1M) Calibration or Standardization is required every time when it is to be used. The glass bulb is very fragile / sensitive and hence great care is required for its use. It does not function properly in some organic solvents like pure alcohol, pure acetic acid, gelatin etc. It cannot be used with ordinary potentiometers but it can be used with electronic potentiometers. The glass electrode has high electrical resistance.

15. Applications of pH metry: (3M Or 4M ) The pH of number of test or sample solutions can be measured accurately and in quick time. The pH of coloured solutions, colloidal solutions, viscous protein media, complex and poisonous solutions can be determined. The equivalence point of acid-base titration in non-aqueous medium can be determined. pH meters are widely used to monitor the pH of water in domestic water supply. pH meters are also used in almost all industries to measure the pH. pH meters are also used to monitor the rate of corrosion by measuring the pH of the medium in which the metal is present.

16. SPECTROMETRY Laws Of Spectrometry: IMP Terms /Concepts :

17. LAWS OF SPECTROMETRY: Lambert’s Law and Beer’s Law Or Beer’s-Lambert’s Law

18. Single Beam Spectrophotometer Cells or Cuvettes Filters

19. Single Beam Spectrophotometer :

20. Applications: Single beam spectrophotometer is used to measure absorbance or transmittance of the materials. Single beam spectrophotometer is used to find out concentration of unknown solutions as follows, Determination of unknown conc. by calculation:

21. 2) Determination of unknown conc. by Graph : If absorbance of various standard or known solutions are measured at different concentrations and the values of concentration of standard solution (C 1) are known, then concentration of unknown solution (C 2 ) can be determined as shown in the graph.

22. Chromatography Gas-Liquid Chromatography (GLC)

23. Chromatography is a physical method of separation where the components of the mixture are separated over support due to differential movement caused by continuous distribution between a stationary and mobile phase. ( Remark: Stationary phase may be solid or liquid whereas mobile phase may be liquid or gas)

24. What is Chromatography? Chromatography is a technique for separating mixtures into their components in order to analyze, identify, purify, and/or quantify the mixture or components. Separate Analyze Identify Purify Quantify Components Mixture

25. Illustration of Chromatography Components Affinity to Stationary Phase Affinity to Mobile Phase Blue ---------------- Insoluble in Mobile Phase Black         Red        Yellow           Mixture Components Separation Stationary Phase Mobile Phase

26. Classification of Chromatography On the basis of Stationary Phase

27. Gas Liquid Chromatography Here the mobile phase is an unreactive gas ( eg Nitrogen) flowing through a tube. And the stationary phase is an involatile liquid held on particles of a solid support.

28. In the animation below the red molecules are more soluble in the liquid (or less volatile) than are the green molecules.

29. Oven Detector Injection port Nitrogen cylinder Column Recorder

30. Gas Liquid Chromatography (GLC):

31. GLC is Gas Liquid Chromatography technique which is used for separation of mixture into its individual pure components by moving gaseous mobile phase passing over a liquid stationary phase. Principle: In GLC, the mixture to be separated is vaporized and passed through the column along with inert gas . The column is packed with a solid porous material and low volatile liquid is get adsorbed on it . Here, inert gas acts as a mobile phase whereas the volatile liquid acts as a stationary phase. The components of mixture separate according to their increasing order of partition coefficients / distribution coefficients.

32. Advantages of GLC: 1) It gives satisfactory separation of even complex mixtures. 2) Small quantities of sample (in micro scale) can be analyzed with the help of GLC. 3) Mostly, sample cannot be wasted. 4)The results obtained are more accurate and reliable. 5)Results are obtained within short time period. 6) Any compound that can be volatilized can be separated. 7) Most of GLC are now compatible with printer and other devices. So, data can be stored, printed and managed easily. e.g. GCMS

33. Applications: GLC is used For separation of mixture into its pure components individually. For the qualitative and quantitative analysis of components in a mixture. To find out the presence of impurities in a substance. For analyzing fuel gases. For analyzing Auto exhaust gases. For identification of natural products. For the product quality control, For biomedical applications. For analysis of commercial products and in forensic chemistry. For the study of atmospheric pollutants. For the study of reaction mechanism. To separate amines. In petroleum industry for the analysis of crude petroleum products, gasoline, waxes etc. In food industry, it is used to account for the colour and flavor of food.

34. Home Assignments: Q.1) What are the advantages and disadvantages of instrumental methods of chemical analysis? 4M Q.2) Draw neat labeled diagram of glass electrode and explain its principle, construction and working. 4M Q.3) Write short note on ‘Applications of pH-metry’. 4M Q.4) Write short note on 4M a) Lamberts law Or State Lamberts law & derive expression for it. b) Beer-Lamberts law Or State Beer-Lamberts law & derive expression for it. Q.5) With schematic diagram, explain principle, construction and working of single beam spectrophotometer. 4M Or Explain working of single beam spectrophotometer with suitable diagram. How it can be used to determine the concentration of unknown solution? Q.6) With schematic diagram, explain principle, construction and working of gas-liquid chromatography (GLC). 4M Q.7) What is Chromatography? How are they classified on the basis of mobile and stationary phase? 4M Or Give the classification of chromatography. 4M Q.8) What are the applications of GLC? 4M

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