A preliminary study of Raman spectroscopy potential for chromium detection

This paper presents a preliminary study of Raman spectroscopic measurement of chromium traces in leather and its processed forms such as shavings, hydrolyzate and ash. The emphasis is given on the valence of chromium, especially two most stable forms trivalent and hexavalent, as they have adverse effect on human health. Trivalent form is mainly beneficial. Compounds of hexavalent chromium are classified as carcinogens. The conventional methods for chromium assessments (e.g. FAAS) are often time-consuming and destructive. Some of methods give only the total chromium content value, which is not sufficient due to the nature of different valences. The official UV-VIS spectrophotometry is designed mainly for liquid samples. The innovative approach is the study of Raman spectroscopy possibilities. Raman spectroscopy is an efficient method for material identification reflecting the molecular structure. This method provides many benefits such as rapidity, non-invasiveness, no requirements for sample preparation, applicability to various materials. The results of the performed experiments show the hidden potential of Raman spectroscopy for the chromium detection with the benefit of direct determination of valence. The limitation can be by emerging luminescent. Silver colloidal treatment of luminescent samples indicated more intense Raman signal. An agreement was reached with trivalent and hexavalent chromium content in specially treated leather samples and the ash.