Determination of trace phosphate ion with 3,3',5,5'-tetramethylbenzidine using a flotation-extraction preconcentration method and spectrophotometric detection.
A flotation-extraction method for sensitivity enhancement in spectrophotometry is proposed. The method is based on the reaction among molybdate, phosphate and 3,3',5,5'-tetramethylbenzidine (TMB) in acidic medium to form an color charge transfer complex ion. It forms an ion associate with positive ions and floated at the water/benzene interface simultaneously, and then extracted by the DMSO-formic acid directly and determined by spectrophotometry. The proposed method is simple and convenient. The apparent molar absorptivity is 4.03x10(5) L mol(-1) cm(-1) at 458 nm. The proposed method has been applied to the determination of phosphate in wastewater with satisfactory results.
Di
J
J
Department of Chemistry, Suzhou University, Suzhou, Jiangsu 215006, PR China.
Liu
Q
Q
Li
W
W