Determination of Total Cyanide in Water by Flow Injection

Objective To Establish a method of using flow injection in-line cyanide distillation to determine total cyanide in water and wastewater.Methods A QC8000 analyzer in-line cyanide distillation was used.Firstly,a liquid sample was mixed with phosphoric acid and heated to 140℃,then metal-CN~-complexes was irradiated by UV to break down.The HCN(g) from the sample matrix passed through a Teflon membrane and was trapped into a sodium hydroxide solution.The CN~was determined colorimetrically(pyridine-barbituric acid chemistry) at 570 nm.Both standards and samples were distilled in-line.Results The linear range of the method was 2～100 μg/L,detected limit was 0.21 μg/L,The recovery rates were 94.4%～105%.Correlation coefficient was above 0.999.Conclusion The method is simple and sensitive compared with method of standard.