Chromatography & Other Chemical Analysis Techniques - PDF

⋆ ˚｡⋆ GROUP 2 ˚. ᵎᵎˎˊ˗ CHROMATOGRAPHY What is Chromatography? Chromatography is a laboratory technique used to separate, identify, and analyze the components of a mixture. The process involves passing the mixture through a medium where different components travel at different rates, allowing for th...

⋆ ˚｡⋆ GROUP 2 ˚. ᵎᵎˎˊ˗ CHROMATOGRAPHY What is Chromatography? Chromatography is a laboratory technique used to separate, identify, and analyze the components of a mixture. The process involves passing the mixture through a medium where different components travel at different rates, allowing for their separation. Chromatography is widely used in chemical analysis, biochemistry, pharmaceuticals, and environmental testing due to its precision and efficiency. TYPES OF CHROMATOGRAPHY 1. Paper Chromatography ​ Description: Utilizes a strip of paper as the stationary phase. ​ Specific Tools/Chemicals: Filter paper, a solvent (e.g., water, ethanol, or acetone), and a sample solution. ​ Time Required: 10-20 minutes. Time depends on the solvent used and the distance the components need to travel. ​ Accuracy/Margin of Error: Moderately accurate; margin of error depends on sample and solvent purity (~5-10%). ​ Reason for Margin of Error: Variations in paper texture, inconsistent solvent movement, and environmental conditions like humidity can cause minor inaccuracies. ​ Uses: General: Quick qualitative analysis of mixtures. Specific: Identifying pigments in plants, separating amino acids, and​ food testing for artificial dyes. ​ Advantages: Simple, cost-effective, and requires minimal equipment. ​ Disadvantages: [Limited resolution] and not suitable for volatile substances. How to Use the Tool or Conduct Tests: 1. Prepare the sample by dissolving it in a small amount of solvent.  2. Draw a pencil line near the bottom of the filter paper and place a small spot of the sample on the line. 3. Suspend the paper in a container with the solvent, ensuring the spot is above the solvent level. 4. Allow the solvent to travel up the paper, separating the components. 5. Remove the paper, dry it, and analyze the separated spots using [Rf values]. ​ NOTE: Retention factors are a quantitative measure used in chromatography to describe the movement of a substance on a chromatographic medium relative to the solvent front. 2. Thin Layer Chromatography (TLC) ​ Description: Employs a thin layer of silica or alumina on a glass or plastic plate as the stationary phase. ​ Specific Tools/Chemicals: TLC plates, solvents (e.g., ethanol, acetone), and a UV lamp for visualization. ​ Time Required: 5-30 minutes. Time depends on solvent volatility and sample composition. ​ Accuracy/Margin of Error: High accuracy for qualitative analysis; margin of error ~2-5%. ​ Reason for Margin of Error: Factors such as uneven coating of the stationary phase, solvent impurities, and operator handling can introduce small inaccuracies. ​ Uses: General: Fast analysis of mixtures and reaction monitoring. Specific: Identifying pharmaceutical compounds and analyzing essential oils. ​ Advantages: Faster and more sensitive than paper chromatography. ​ Disadvantages: Limited to small-scale analysis. ​ How to Use the Tool or Conduct Tests: 1. Prepare the sample and dissolve it in a suitable solvent. 2. Apply small spots of the sample near the bottom of the TLC plate. 3. Place the plate in a developing chamber with a small amount of solvent. 4. Allow the solvent to ascend the plate, carrying the sample. 5. Remove the plate, mark the solvent front, and visualize the spots under UV light or by staining. 3. Gas Chromatography (GC) ​ Description: Involves a gaseous mobile phase and a solid or liquid stationary phase within a column. ​ Specific Tools/Chemicals: Gas chromatograph, carrier gases (e.g., helium, nitrogen), and sample injectors. ​ Time Required: 5-60 minutes depending on the complexity of the sample. Heavier samples or those requiring temperature programming may take longer. ​ Accuracy/Margin of Error: Extremely high accuracy (error