A simple spectrophotometric method for the determination of cadmium in industrial, environmental, biological and soil samples using 5,7-dibromo-8-hydroxyquinoline.

A very simple, ultra-sensitive and highly selective non-extractive spectrophotometric method for the determination of trace amount of cadmium using 5,7-dibromo-8-hydroxyquinoline (DBHQ) has been developed. DBHQ reacts in a slightly acidic solution with cadmium to give a deep greenish-yellow chelate, which has an absorption maximum at 396 nm. The average molar absorption co-efficient and Sandell's sensitivity were found to be 5.3 x 10(3) L mol(-1) cm(-2) and 20 ng cm(-2) of Cd, respectively. Linear calibration graphs were obtained for 0.1-30 microg mL(-1) of Cd. A large excess of over 50 cations, anions and some common complexing agents do not interfere with the determination. The method was successfully used in the determination of cadmium in several Standard Reference Materials as well as in some environmental waters, biological and soil samples.