The Determination of Trace Copper in water Using Biscyclohexanone Oxaldihydrazone as a Color Reagent by Flow Injection Spectrophotometry

Based on the sensitive and selective reaction of Cu2+ and biscyclohexanone oxaldihydrazone(BCO) in basic solution,a simple,sensitive and low cost,flow injection spectrophotometry method was developed for the determination of copper in surface water.In the research,all chemicals,and flow injection variables have been optimized.And the effects of reaction temperature and foreign ions have been studied in detail.At the optimum test conditions,the reaction of Cu2+ and BCO in basic media proceeds rapidly at room temperature without additional caloric.And the developed method provides a linearity range over 25 to 200 μg·L-1.The linearity equation is A=0.0392×(Cu2+,/μg·L-1) + 0.6657,r2=0.9998.Apparent molar absorption coefficient is 0.89×103 mol·L-1·cm-1.The relative standard deviation(RSD) calculated from 20 times repeated injections is 4.61%(Cu2+,120 μg·L-1).The detection limit(IUPAC) is 2.5 μg·L-1.Analysis frequency is 20 times/h.The parameters of the proposed method were comparable with current national standard methods for the determination of copper in water samples.In the absence of some pretreatment process,such as concentration and separation,the proposed method could test directly copper at trace level(μg·L-1) in surface water with well recoveries.