Spectrophotometric Determination of the Trace Amount of Zinc(II) with 4,5-Dibromo-2-nitro-phenylfluorone(DB-o-NPF)

The reacting condition and application of DB-o-NPF and Zn(Ⅱ) were studied. The results show that with the presence of CPB,the color reagent reacts with Zn(Ⅱ) and forms a stable blue complex in the medium of Sodium Traborate -NaOH buffer solution (pH=10.5).It remains stable for 4 hours at least.The apparent light absorption coefficient per mol e=1.13×10~5L·mol~(-1)·cm~(-1) and the maximum absorption happens at λ=624 nm.Beer′s law is obeyed in the concentration range of 0～0.64 μg/mL for Zn(Ⅱ).The proposed method has good sensitivity and selectivity.It has been applied to the determination of trace amount of Zn(Ⅱ) in zinc gluconate tablet and table salt of added zinc with satisfactory results.A better consistency was obtained through a comparison between the determination results of this proposed method and the AAS method.