Measurement of Chromium Content in Ramie through the DPC Color Development Spectrophotometry

Ultraviolet(UV) spectrophotometry was used to test the chromium(Cr) content of bast fiber by using diphenylcarbazide(DPC) as color reagent.The results showed that complexes were formed from Cr(VI) ions and DPC under phosphoric acid condition.There was a maximum positive absorption peak at 540nm.Cr(VI) concentration(in the range of 0.004-1.000mg·L-1) and the absorbance of complex obeyed the Lambert-Beer law.The optimal technology was dropping volume of phosphoric acid 0.4-0.6mL,DPC content 2.0-4.0mL,and coloration time 5-10min.The total Cr content in bast fiber samples from a Cr mine area was tested,and the results showed that the total Cr contents decreased along the water flow of river.