Podcast
Questions and Answers
What is the first step in the preparation of a sample for analysis?
What is the first step in the preparation of a sample for analysis?
- Perform necessary chemical separation
- Adjust the pH
- Run a blank
- Measure the amount (correct)
Which of the following is NOT a step in the preparation of a sample for analysis?
Which of the following is NOT a step in the preparation of a sample for analysis?
- Chromatography (correct)
- Extraction into an immiscible solvent
- Drying, if needed
- Performing the measurement
What is the purpose of running a blank during the analytical process?
What is the purpose of running a blank during the analytical process?
- To perform necessary chemical separation
- To adjust the pH of the sample
- To remove or mask interferences (correct)
- To convert the analyte to a more suitable form
In analytical chemistry, what is the main role of an analyst?
In analytical chemistry, what is the main role of an analyst?
Which of the following is an application of analytical chemistry?
Which of the following is an application of analytical chemistry?
What is typically done during the 'extraction into an immiscible solvent' step in sample preparation?
What is typically done during the 'extraction into an immiscible solvent' step in sample preparation?
Which of the following methods is used to remove interferences during analysis?
Which of the following methods is used to remove interferences during analysis?
Why is it important for an analyst to study the theories of analytical processes?
Why is it important for an analyst to study the theories of analytical processes?
What role does distillation play in analytical chemistry?
What role does distillation play in analytical chemistry?
What is a key aspect of quantitative analysis in analytical chemistry?
What is a key aspect of quantitative analysis in analytical chemistry?
Study Notes
Classification of Analytical Methods
- According to extent of analysis:
- Ultimate: determines the percentage of elements in a substance
- Proximate: determines the approximate amount of a constituent, often indirect and crude (e.g., crude protein and crude fat)
Classification of Analytical Methods (continued)
- According to amount of sample:
- Macro analysis: requires 0.1g or more of sample
- Semi-micro: requires 0.01g to 0.1g of sample
- Micro: requires 1-10mg of sample
- Ultramicro: requires only micrograms of sample
Classification of Analytical Methods (continued)
- According to amount of analyte:
- Major constituent: more than 1% of the sample
- Minor constituent: 0.01% to 1% of the sample
- Trace constituent: less than 0.01% of the sample
Absolute/Classical Methods
- Gravimetry: measures mass or volume of a substance related to the analyte through a chemical reaction
- Titrimetry: measures the volume of a substance required to react with the analyte
Instrumental Methods
- Based on measuring a physical/chemical property related to concentration, expressed in a mathematical relationship
- Examples: UV-Vis spectrophotometry (A=εbc)
Applications of Analytical Chemistry
- Establishing economic value
- Determining health hazards
- Diagnosing diseases
- Controlling quality
- Relating properties to composition and structure
- Conducting research
- Human Genome Project
- Lab-on-a-Chip (microfluidics) and Nanotechnology
- Environmental Analysis
- Forensic Science
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Description
Test your knowledge on the classification of methods of chemical analysis, including the determination of total nitrogen content and crude protein value. Explore different techniques according to the extent of analysis and percentage of elements in a substance.
