For determination of chromium, the diphenylcarbohydrazide reagent is added to an acidified sample containing chromium. The reaction between chromium and the reagent causes a purple colored complex to form; the greater the concentration, the deeper the color. A color comparator cube is included for an accurate, side-by-side, visual analysis to determine chromium concentration. These reagents are designed to be used with samples that have an expected chromium range of 0.0 to 1.0 mg/L (ppm) CrVI.