The micellar mediated trace level estn. of mercury in industrial effluent sample by the rhodamine B hydrazide spirolactam ring opening process is described. The catalytic reaction of mercuric ion with colorless rhodamine B hydrazide to form pink colored rhodamine B through amide bond cleavage at pH 5 forms the basis of this reaction. The dye obtained was extd. from the aq. phase into non-ionic surfactant using Triton X-114 through cloud point formation and its absorbance was measured at 556 nm. The reaction conditions such as concns. of rhodamine B hydrazide and Triton X-114, effect of NaCl concn. on cloud point temp. and the efficiency of extn. were optimized. The selectivity of the method towards mercury in the presence of various ions was studied. The validity of the method was examd. by spiking real samples with known amts. of mercury and carrying out recovery studies. The results obtained by the proposed method were compared with the std. dithiazone method. The preconcn. and enrichment factors were found to be 5 and 12 resp. The limit of detection and the linear range were found to be 1.4 ng ml-1 and 10-100 ng ml-1 resp. The relative std. deviation was found to be 0.35% at 20 ng ml-1
