Principles

Absorption spectrophotometry in the ultraviolet and visible range

Figure 1 - Spectral range of electromagnetic radiation

Figure 2 - Electronic transitions of atoms and molecules

Figure 3 - Some absorption spectra of molecules

Figure 4 - Diagram of an absorption cell

Figure 5 - Plotting the calibration curve and determining unknown concentrations

Figure 6 - Effect of linear regression on concentration determination

Figure 7 - Diagram of single-beam devices

Figure 8 - Schematic diagram of the dual-beam spectrophotometer (doc. Oriel)

Figure 9 - Emission spectra of tungsten-halogen and deuterium lamps

Figure 10 - Assembly of monochromators and spectrographs

Figure 11 - Effect of slit width on the spectrum of a monochromatic line

Figure 12 - Effect of resolution on the absorbance of benzene gas

Figure 13 - Measurement uncertainty as a function of absorbance

Figure 14 - Variations in absorbance with repeatability of wavelength positioning

Figure 16 - Spectra of solutions used to measure stray light levels

Figure 17 - Background noise on the baseline

Figure 18 - Broadcast correction

Figure 19 - Single variable linear regression

Figure 20 - Standard deviation of prediction error with calibration and validation samples

Figure 21 - Validation by the residual method

Figure 22 - Use of residues to detect anomalies in the analysis of nitrates in drinking water (model created using nitrates and humic acids)

Figure 23 - Evolution of selectivity  in different cases