Instrumentation 1


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Instrumentation 1

  1. 1. InstrumentationDeals with the theoretical and practical aspects ofdifferent instruments and instrumental techniquesinvolved in Analytical Chemistry,Which is a branch of chemistry involving separation,identification and determination of components of asample
  2. 2. 1 M = 1 mole/1 liter solution
  3. 3. Classification of analyte• Major component 1-100%• Minor component 0.01 to <1.00%• Trace component 1ppb – 100 ppm• Ultra-trace component <1ppb
  4. 4. Analytical method on the basis of sample size Method Weight mg Volume µl Meso >100 >100 Semi-micro 10-100 50-100 Micro 1-<10 <50Ultra micro <1
  5. 5. Problems• Prepare a solution of 1 Molar HCl• Prepare a solution of 1 Molar NaOH• Prepare a solution of 1 Molar H2SO4• Prepare a solution of 1 Molar Oxalic acid dihydrate• Prepare a solution of 1 Normal Oxalic acid dihydrate
  6. 6. Problem• You have a stock solution of NaOH having concentration of 1 M, prepare 500 mL solutions of 0.1N, 0.2N, 0.3N using dilution equation
  7. 7. Problem• What is pCl and pNa of a 5.00g/L solution of NaCl? Na Cl NaCl Given Molar pNa/pCl 23 35.5 58.5 5g/L 0.085470 1.068186
  8. 8. Selecting an Analytical TechniqueDefining the problem first:1. What accuracy and precision is required?2. How much sample is available?3. What is the concentration range of the analyte?4. What components of the sample cause interference?5. What are the physical and chemical properties of the sample matrix or interfering species?6. How many samples are to be analyzed?
  9. 9. Numerical Criteria for Selecting Analytical Technique1. Precision2. Bias (A systematic error occurring in a chemical measurement that is inherent in the method itself or caused by some artifact in the system, such as a temperature effect)3. Sensitivity (LOD and LOQ)4. Detection Limits5. Concentration Range6. Selectivity
  10. 10. Other Characteristics to Be Considered in Method of Choice1. Speed2. Ease and Convenience3. Cost and availability of instrument4. Per-sample cost
  11. 11. Sampling• Homogeneous materials (grab sample, random)• Heterogeneous materials (Several samples are required) that include1- Gross sampling2- Laboratory sample (taken from gross sampling and homogenized)3- Analysis samples (taken from laboratory sample)4- Biological fluids (sampling time and preservation)5- Storage of the samples (suitable containers, low temp)6- Urine samples (acidified pH4.5)
  12. 12. Preparation of samples• Weighing of the sample• Samples are prepared in replicates• Solid samples must be dissolved• Ashing or digestion for trace metals• Preparation of blank
  13. 13. Chemical separation• Includes precipitation, extraction, chromatography, dialysis and distillation, and1- Eliminates interferences (analyte away from matrix)2- Provides suitable selectivity in measurement
  14. 14. Classification of Analytical Methods1-Classical methods – Gravimetric – Titrimetric2-Instrumental methods – Spectroscopy – Electroanalytical – Chromatography
  15. 15. Data Analysis• The concentration of analyte in the sample solution is used to calculate the concentration of analyte in the original sample, and is expressed in relative terms• Precision is expressed by SD of RSD• Finally Critical evaluation of results (To see whether results relate to the analytical problem, as stated before the experiment