Abstract：A new method for the determination of trace Cr by spectrophotometry was developed. The method was based on the fact that Cr could react with phen and bright yellow (BY), forming a stable ion-association complex ［Cr(phen)］BY3 in NaAc-HAc buffer solution at pH 5.7, which resulted in a obvious enhancement of absorbence at the maximum absorption peak of 382 nm. The effect of acidity, reagent dosage, surfactant, reaction temperature and reaction time was investigated to obtain the optimal conditions. The Beer’s law was obeyed in the range of 0-0.30 μg/mL for Cr. The apparent molar absorption coefficient was 1.31×105 L·mol-1·cm-1 and the detection limit was 3.63 μg/L.The method has been applied to the determination of Cr in electroplating wastewater samples. The relative standard deviations (RSD, n=5) were 1.9 % and 1.4 %, respectively and the recoveries were 96 % and 99 %,respectively.
