Instrumentation

Ultraviolet and visible absorption spectrophotometry

Figure 1 - Spectral range of electromagnetic radiation

Figure 2 - Electronic transitions in atoms and molecules

Figure 3 - Some absorption spectra of molecules

Figure 4 - Diagram of an absorption cell

Figure 5 - Plotting the calibration line 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 double-beam spectrophotometer (doc. Oriel)

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

Figure 10 - Monochromator and spectrograph assembly

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

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

Figure 13 - Measurement uncertainty as a function of absorbance

Figure 14 - Variations in absorbance with wavelength positioning repeatability

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

Figure 17 - Background noise on the baseline

Figure 18 - Diffusion correction

Figure 19 - Single-variable linear regression

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

Figure 21 - Validation using the residual method

Figure 22 - Use of residues to detect anomalies in nitrate analysis of drinking water (model carried out with nitrates and humic acids)

Figure 23 - Evolution of  selectivity in different cases