EPA-ORD: Method 218.6: Hexavalent Chromium in Water by Ion Chromatography
Brief Method Summary
An aqueous sample is filtered through a 0.45 um filter and the filtrate is adjusted to a pH of 9-9.5 with a concentrated buffer solution. A measured volume of the sample (50-250 uL) is introduced into the ion chromatograph. A guard column removes organics from the sample before the Cr (VI), as CrO4 2- , is separated on a high capacity anion exchange separator column. Post-column derivatization of the Cr (VI) with diphenylcarbazide is followed by detection of the colored complex at 530 nm.
Scope and Application
This method provides procedures for determination of dissolved hexavalent chromium (as CrO4 2-) in drinking water, groundwater, and industrial wastewater effluents.
Applicable Conc Range: 1-10,000 ug/L