Chapter 0 - The Analytical Process Flashcards
(22 cards)
Quantitative chemical analysis
Measurement of how much of a chemical substance is present
Qualitative chemical analysis
Seeks to identify one or more constituents of a substance
Sampling
Procuring a representative sample to measure
Homogenous
Composition is the same throughout
Heterogeneous
Composition differs from region to region
Analytes
Substances being measured
Quantitative transfer
Complete transfer
Slurry
A suspension of solid in a liquid
Aqueous solution
Solution of anything in water
Supernatant liquid
Liquid above the packed solid
Sample preparation
Transforming a sample into a state that is suitable for analysis
Calibration/standard curve
A graph of detector response as a function of analyte concentration
Standard solutions
Contain known concentration
General steps in the analytical process
- Formulating the question
- Selecting analytical procedure
- Sampling
- Sample preparation
- Analysis
- Reporting and interpretation
- Drawing conclusions
Aliquots
Portions
Random heterogeneous material
Differences in composition occur randomly and on a fine scale
Random sample
Collected by taking portions from the desired number of segments chosen at random
Segregate heterogeneous material
Large regions have obviously different compositions so a representative composite sample must be constructed
Species
Any chemical of interest
Interference
Occurs when a species other than analyte increases or decreases the response of the analytical method and makes it appear that there is more or less analyte than is actually present
Masking
The transformation of an interfering species into a form that is not detected
