CrO42- is derivatized with 1,5-diphenylcarbazide in a post-column reactor and is detected spectrophotometrically at a wavelength of 530 nm. Cr(VI) is qualitatively identified via retention time, and the concentration of CrO42- in the sample is calculated using the integrated peak area and the external standard technique. Results are reported in units of μg/L of Cr(VI).