Abstract

BREMER NETO, Hermann; GRANER, Celso Augusto Fessel; PEZZATO, Luiz Edivaldo  and  PADOVANI, Carlos Roberto. The spectrophotometric method on the routine of 1,5-diphenylcarbazide was adjusted on chromium determination in feces, after its utilization as a biological marker as chromium (III) oxide. Cienc. Rural [online]. 2005, vol.35, n.3, pp. 691-697. ISSN 0103-8478.  http://dx.doi.org/10.1590/S0103-84782005000300033.

This work aims at adjusting the spectrophotometric method of 1,5-diphenylcarbazide for the determination of chromium in feces, as a biological marker. Factors that could interfere with the transformation of chromium (III) into chromium (VI) were tested, as the metal recovery, the sample amount, the amount and the order of use of the oxidant acids of the wet digestion, digestion temperature and digestion time, loss of chromium by volatilization as chromyl chlorid. However the interference of these factors were not statistically determined. In the adjusted method, the sample is classically digested by nitric/perchloric acid mixture leading to the oxidation of chromium (III) to chromium (VI), and an aliquot of the diluted extract is used for reaction with 1,5-diphenylcarbazide; absorbance was measured at 550nm, using 1cm path length optical cuvettes. Potassium dichromate was used as a standard substance to obtain the standard curve ranging from 0.25mg.mL^-1 to 2.5mg.mL^-1 of Cr₂O₃ (1mg Cr₂O₃ º 1.9355mg K₂Cr₂O₇).

Keywords : chromium (III) oxide; biological marker; spectrophotometric determination; feces.