UV-Vis spectroscopy is widely used due to its simplicity, sensitivity, and versatility. Key applications include:
Spectrophotometric Titrations
Monitoring absorbance changes during titration to determine analyte concentrations.
Types:
Direct: Analyte absorbs light; absorbance changes with titrant addition (e.g., dye titration with a bleaching agent).
Indirect: Absorbance of an indicator changes during titration (e.g., acid-base titration with a pH indicator).
Back Titration: Excess titrant is measured after reacting with the analyte (e.g., calcium carbonate analysis).
Advantages: High sensitivity, selectivity, and automation.
Applications: Environmental analysis (pollutants), pharmaceuticals (active ingredients), food (additives).
Applications:
Environmental: Pollutant analysis (nitrates, phosphates).
Pharmaceuticals: Active ingredient quantification.
Food: Additive and colorant measurement.
Single Component Analysis
Determining one analyte's concentration using its unique absorbance.
Methods:
Direct Measurement: At λₘₐₓ using a calibration curve (e.g., caffeine in beverages).
Standard Addition: Accounting for matrix effects (e.g., vitamin C in juice).
Calibration Curve: Relating absorbance to concentration (e.g., cholesterol measurement).
Advantages: Simple and accurate for well-defined samples.
Limitations: Interference from other species and the need for a unique absorption peak.
Applications: Clinical diagnostics (hemoglobin), chemical manufacturing, research.
Applications:
Clinical: Hemoglobin measurement.
Manufacturing: Reactant monitoring.
Research: Isolated compound analysis.
Multi-Component Analysis of UV Vis spectroscopy
Determining concentrations of multiple species in a mixture.
Techniques:
Simultaneous Equations: Solve absorbance equations for components (e.g., drug mixtures).
Spectrum Subtraction: Isolates one component by subtracting another.
Derivative Spectroscopy: Resolves overlapping peaks.
Multivariate Calibration: Statistical methods (e.g., Partial Least Squares) for complex mixtures.
Advantages: Efficient, reduces sample volume.
Limitations: Complex analysis requiring calibration and software.
Applications: Pharmaceuticals (active ingredients), environmental monitoring (pollutants), food (colorants).
Applications:
Pharmaceuticals: Multi-drug assays.
Environmental: Detecting multiple pollutants.
Food: Mixture analysis of additives and preservatives.