Analytical Chemistry Chapter 1

Study Notes

Definition of Analytical Chemistry
Focuses on the chemical characterization of matter.
Employs various techniques for qualitative, quantitative, and structural analysis of substances.
Involves separation, identification, and determination of components in samples.
Types of Chemical Analysis
Selective Analysis: Preferences for particular analytes but possible interference from other substances.
Specific Analysis: Exclusively targets a substance of interest without interference.
Components of the Chemical System
Analyte: The species of interest in the analysis.
Matrix: The part of the sample that does not include the analyte.
Applications of Analytical Chemistry
Quality control (QC) in industries.
Monitoring environmental pollutants.
Clinical and biological research.
Geological assays.
Fundamental and applied scientific research.
Analytical Methods Overview
Qualitative Methods: Identify atomic/molecular species or functional groups present in samples.
Quantitative Methods: Provide numerical data on the absolute or relative quantities of elements or compounds.
Types of Analytical Techniques
Wet-analysis: Uses precipitation, titrimetry, gravimetry.
Instrumental Methods: Utilizes advanced instruments to determine physical and chemical properties of analytes.
Destructive Analysis: Consumes or alters the sample, common in wet-analysis.
Non-destructive Analysis: Preserves the sample for further testing, seen in certain instrumental methods.
Classification of Analyte Concentration
Major: Above 1% concentration.
Minor: Between 0.01% and 1.00% concentration.
Trace: Below 0.01% concentration.
Sample Size Classification
Macro: Greater than 100 mg (or 100 µL).
Semi-Micro: 10 to 100 mg (or 50-100 µL).
Micro: 1.0 to 10 mg.
Ultramicro: Less than 1.0 mg.
Analytical Methods by Purpose
Proximate/Partial Analysis: Focuses on a limited number of species in a sample.
Ultimate Analysis: Analyzes every element's amount in a sample.
Complete Analysis: Quantifies each element based on the composition of the sample.
Selecting an Analytical Method
Consider accuracy and sensitivity required.
Evaluate time and budget constraints.
Assess available tools and equipment.
Determine the sample's complexity and the number of constituent parts.
Sampling Protocol
Proper storage and handling necessary for sample integrity.
Maintain a chain of custody for reliability.
Sampling Process
Gross Sample: Initial representative sample collected on-site.
Laboratory Sample: Homogenized sample for lab analysis.
Analysis Sample: Subset of laboratory sample for actual testing.
Sample Processing Techniques
Pre-treatment methods include grinding, filtering, and solvent dissolution.
Concentration techniques for low analyte amounts.
Managing Interferences
Utilize methods specific to the analyte for accuracy.
Masking to eliminate interferences by converting them into non-interfering forms.
Separation techniques include precipitation, chromatography, and ion exchange.
Calibration in Analytical Chemistry
Calibration standardizes the output of analysis or instrument readings.
Achieved through calibration curves, which plot instrument response against analyte concentration.
Standard Addition: Involves adding a known quantity of standard to the sample and measuring response changes.
Result Calculation
Consider stoichiometry of reactions involved.
Relate gathered data to the property measured and derive necessary equations.
Estimating Reliability
Use appropriate statistical tests to evaluate data quality and analysis methods used.