Hydrogen peroxide interference in the determination of chromium(VI) by the diphenylcarbazide method

Chromium speciation in seawater: The probable role of hydrogen peroxide

“…Literature values of Cr(V1) : Cr(II1) range from < 1 to 70 for oxic conditions (Table 1). Earlier results (Chuecas and Riley 1966;Fukai 1967) giving values < 1 were probably affected by alteration due to Cr(V1) reduction on storage at low pH (Nakayama et al 1981a,b,c,d;Ahem et al 1985;Pettine et al 1988). The inconsistency of past literature data on Cr speciation might also reflect variable extraction yields of organically bound Cr(II1) (Nakayama et al 198 la&,& Jeandel and Minster 1984).…”

“…1985) due to its ability to rapidly reduce Cr(V1) in acidic solutions to Cr(II1). The concentration of reagents needed to eliminate this interference was determined from results of a previous study on the effect of H,O, on Cr(V1) determination by the above method (Pettine et al 1988). The absorbance was measured at 540 nm on a Carlo Erba spectrophotometer in 5-cm cells.…”

“…The approximately first-order pH dependence of the reaction is In our next series of measurements we examined the effect of H,Oz concentrations on the rates of oxidation of Cr(II1) (1.9 /IM) at 25°C and pH 8.OOkO.03. Because the sensitivity of the diphenylcarbazide method for determining Cr(V1) (Pettine et al 1988) (Fig. 6) indicates a first-order dependence of Cr(II1) oxidation over a large H,O, concentration range (0. l-2.6 mM)-a factor of 60-l ,400 times greater than the Cr(II1) concentration.…”

Metals in River Water

“…These include 1,5-diphenylcarbazide, 167,264,265 beryllon, 266 and iodide hexadecylpyridinium couplex. 267,268 A spectrophotometric method 264 for determination of total chromium in natural waters with high mineral contents (e.g., alkaline earths) is based on digestion of the sample at 80 °C with alkaline hydrogen peroxide followed by decomposition of excess hydrogen peroxide with trichloroacetic acid and addition of ethanolic diphenylcarbazide.…”

“…Pettine et al 265 studied hydrogen peroxide interference in the determination of chromium(VI) by the diphenylcarbazide method. Hexavalent chromium is reduced to the trivalent state under acidic conditions.…”