Derivative Spectroscopy

On the role of citrate in 12-molybdophosphoric-acid methods for quantification of phosphate in the presence of ATP

“…Furthermore, small differences are observed in the values of the second derivatives which can be due to changes in the molar absorptivities or in the spectral width of the corresponding zero-order spectra. 21,22 These results suggest that the transition S 0 → S 1 becomes more complex when malachite green is adsorbed on 12-MPA nanoparticles, in the presence of PF68, forming the complexes I 1 , I 2 and F , and the spectral components of this transition appear closer in energy in the first intermediate I 1 .…”

“…Contrasting the higher extinction coefficient reported at 640 nm, 2 the component at 585 nm presents higher sensitivity in the second derivative spectrum. However, it is known that derivative spectra have a lower signal to noise ratio than the corresponding zero order spectra, 21,22 thus justifying the use of absorbance measurements for analytical purposes in the absence of interferences.…”