COMPARATIVE-STUDIES OF THE DETERMINATION OF CYANIDE AT LOW CONCENTRATION LEVELS IN WASTE-WATERS

Different methods for the determination of cyanide in waste waters wer e compared. After formation of the stable tetracyanonickelate(II) anio n complex spectrophotometric, polarographic and atomic absorption spec trometric methods were used as off-line systems. Potentiometric determ ination with a flow-injection system was used on-line. Criteria for th e comparison of methods were the limit of detection, linear range, pre cision, recovery and analysis time. The on-line analysis provided the simplest and most rapid method with a limit of detection of 60 mug l-1 . All the methods used showed a cyanide recovery in waste waters in th e range 90-104%. The influence of some interfering ions was also teste d.