Continuous on-line true titrations by feedback based flow ratiometry: application to potentiometric acidbase titrations

The use of visible spectrometry, applied to the chromatic characterization of Roman wall paintings, allows easy and trustworthy grouping of the samples studied. The use of other spectroscopic techniques as Fourier transform infrared (FTIR) and energy dispersive X-ray fluorescence (EDS) in conjunction with X-ray diffraction (XRD) allows good identification of the substances present in the pictorial layers that define and differentiate each chromatic group. In this paper, a study of 21 Roman wall painting samples, from Cripta del Museo and Alcazaba (Merida, Badajoz, Spain), is described.