Overview of Analytical Chemistry
Key concepts, techniques, and applications
1. Definition & Scope
| Aspect |
Description |
| Analytical Chemistry |
The branch of chemistry concerned with the qualitative and quantitative determination of chemical components in substances. |
| Primary Goals |
1. Identify what substances are present (qualitative analysis). 2. Measure how much of each substance is present (quantitative analysis). |
| Fields of Application |
Environmental monitoring, pharmaceuticals, food safety, forensics, clinical diagnostics, materials science, industrial process control. |
2. Classical vs. Modern Approaches
| Category |
Classical Techniques |
Modern (Instrumental) Techniques |
| Qualitative |
Spot tests, flame tests, precipitation reactions |
Mass spectrometry (MS), infrared spectroscopy (IR), nuclear magnetic resonance (NMR) |
| Quantitative |
Gravimetry, titrimetry (acid‑base, redox, complexometric) |
Atomic absorption spectroscopy (AAS), inductively coupled plasma (ICP‑OES/MS), chromatography (GC, HPLC), electrochemical sensors |
| Data Handling |
Manual calculations, tables |
Computer‑aided data acquisition, chemometrics, statistical software |
3. Core Analytical Techniques
3.1 Spectroscopy
| Technique |
Principle |
Typical Use |
| UV‑Vis |
Absorption of ultraviolet/visible light by electrons |
Determining concentration of colored compounds, nucleic acids, transition‑metal complexes |
| IR |
Molecular vibrations absorb IR radiation |
Identifying functional groups, polymer analysis |
| Raman |
Inelastic scattering of monochromatic light |
Complementary to IR, useful for aqueous samples |
| Fluorescence |
Emission of light from excited molecules |
Trace analysis of fluorescent tags, environmental pollutants |
| Atomic Spectroscopy (AAS, ICP‑OES/MS) |
Excitation of atoms → emission/absorption of characteristic wavelengths |
Metal ion determination in water, soils, biological fluids |
3.2 Chromatography
| Technique |
Separation Mechanism |
Detector Options |
| Gas Chromatography (GC) |
Volatility & interaction with stationary phase (gas‑liquid) |
FID, TCD, MS |
| High‑Performance Liquid Chromatography (HPLC) |
Partition/adsorption on a packed column (liquid‑liquid) |
UV‑Vis, PDA, FLD, MS |
| Thin‑Layer Chromatography (TLC) |
Capillary action on a coated plate |
Visual staining, UV illumination |
| Supercritical Fluid Chromatography (SFC) |
Supercritical CO₂ as mobile phase |
UV, MS |
3.3 Electrochemical Methods
| Method |
Principle |
Applications |
| Potentiometry (e.g., pH meter, ion‑selective electrodes) |
Measure potential difference at zero current |
pH, ion concentration in environmental/water samples |
| Voltammetry (e.g., cyclic voltammetry) |
Current response to applied potential |
Redox‑active species, trace metal detection |
| Amperometry |
Current at fixed potential proportional to analyte concentration |
Glucose sensors, environmental monitoring |
3.4 Mass Spectrometry (MS)
| Variant |
Ionization Technique |
Typical Use |
| GC‑MS |
Electron impact (EI), chemical ionization (CI) |
Volatile organics, drug metabolites |
| LC‑MS/MS |
Elect |
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