Analytical Chemistry

Methods and techniques for identifying and quantifying chemical substances

Overview

Analytical chemistry develops methods to determine what substances are present (qualitative analysis) and how much is present (quantitative analysis). It's essential in pharmaceuticals, environmental monitoring, food safety, and forensic science.

⚖️ Titrations ▼

Acid-Base Titration

Determines concentration of acid or base:

  • Equivalence Point: Moles of acid = moles of base
  • End Point: Visual indicator change (pH indicator)
  • Calculation: M₁V₁ = M₂V₂

Redox Titration

  • Based on oxidation-reduction reactions
  • Examples: Permanganate, iodometric titrations
  • Used for Fe²⁺, H₂O₂, vitamin C determination

Complexometric Titration

  • Uses EDTA to complex metal ions
  • Determines hardness of water (Ca²⁺, Mg²⁺)
  • Eriochrome Black T as indicator

Precipitation Titration

  • Forms insoluble precipitate
  • Example: Ag⁺ + Cl⁻ → AgCl(s)
  • Used for halide determination
📊 Chromatography ▼

Principle

Separation based on differential partitioning between mobile and stationary phases.

Types

  • Thin Layer (TLC): Simple, quick separation
  • Column Chromatography: Large-scale separation
  • Gas (GC): Volatile compounds, high resolution
  • High Performance Liquid (HPLC): Non-volatile compounds
  • Ion Exchange: Separates ions

Retention Factor (Rf)

Rf = distance traveled by compound / distance traveled by solvent

Used to identify compounds in TLC

Applications

  • Drug purity testing
  • Environmental pollutant analysis
  • Food quality control
  • Forensic analysis
🔬 Spectroscopy ▼

UV-Visible Spectroscopy

  • Measures electronic transitions
  • Beer-Lambert Law: A = εcl
  • Quantitative analysis of colored compounds
  • Wavelength range: 200-800 nm

Infrared (IR) Spectroscopy

  • Vibrational transitions
  • Fingerprint region: 1500-500 cm⁻¹
  • Functional group identification
  • Qualitative analysis

NMR Spectroscopy

  • Nuclear magnetic resonance
  • Reveals molecular structure
  • Chemical shifts indicate environment
  • Most powerful for organic compounds

Mass Spectrometry (MS)

  • Measures mass-to-charge ratio
  • Determines molecular weight
  • Fragment analysis for structure
  • Combined with GC or LC (GC-MS, LC-MS)

Atomic Absorption/Emission

  • Quantitative analysis of metals
  • Very sensitive (ppb levels)
  • Used in environmental and clinical analysis
📈 Quantitative Analysis ▼

Calibration Methods

  • External Standard: Compare unknown to standard
  • Internal Standard: Add known amount of different compound
  • Standard Addition: Add known amounts to sample

Detection Limits

  • Limit of Detection (LOD): Lowest detectable concentration
  • Limit of Quantification (LOQ): Lowest quantifiable concentration
  • Critical for trace analysis

Accuracy and Precision

  • Accuracy: Closeness to true value
  • Precision: Reproducibility of measurements
  • Both important for reliable results

Statistical Analysis

  • Mean, standard deviation
  • Confidence intervals
  • t-tests for significance
🌍 Applications ▼

Environmental Analysis

  • Water quality testing
  • Air pollution monitoring
  • Soil contamination analysis

Clinical Chemistry

  • Blood glucose monitoring
  • Drug level testing
  • Hormone analysis

Food Analysis

  • Nutritional labeling
  • Contaminant detection
  • Pesticide residues

Forensic Analysis

  • Drug identification
  • Toxicology
  • Trace evidence

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