NOVEL SPECTROCHEMICAL DETERMINATION OF CADMIUM USING 2-(BENZYLIDENEAMINO) ETHANESULPHONIC ACID

Abstract

2-(Benzylideneamino)-ethanesulphonic acid, BA, (C9H11NSO3) was synthesized by reacting taurine (C2H7SO3) with benzaldehyde (C7H6O) in alkaline medium under reflux. To determine Cd in aqueous system, the BA was reacted with Cd2+ under specified conditions to produce BA-Cd charge-transfer complex. This complex was found to have purple colour with an absorption maximum (λmax) at 360 nm and molar absorptivity (ε) of 8.522 x 103 lmol-1cm-1. Beer’s law is obeyed up to 6.0µg/mL. The correlation coefficient (r) is approx. 1. The optimum BA concentration and pH are found to be 0.720 % (m/v) and 12.50, respectively. The limit of detection (LOD), limit of quantitation (LOQ) and method sensitivity (MS) are estimated at 0.0736µg/mL, 0.0764µg/mL and 0.0375, respectively. The reaction time, stability of the reaction mixture and reagent blank were investigated and found to be 20minutes and 80minutes, respectively. The best order of addition of reagents is established as; BA + Cd2+ + NaOH + methylamine. The extent of ionic interference in this method has been quantitatively evaluated. The most tolerated ions are Ag+, NO3- (ô€€€ô€€ô€€ô€€ ô€€€ô€€ô€€‚ô€€ˆô€€„ô€€…ô€€†ô€€‡ô€€‚ô€€ˆ max) and least tolerated ions are Ni2+, SO42- (5.00 ô€€€ô€€ô€€‚ô€€ƒô€€„ô€€…ô€€†ô€€‡ô€€‚ô€€ˆô€€‰ô€€„ô€€Šô€€‹ô€€Œ. Recovery of cadmium from spiked water samples shows good results (99.5- 106.75%). This method has also been applied to the determination of cadmium in portable and waste waters and soil sample. Results are in good agreement with those obtained by a standard method, Atomic Absorption Spectrometry. Keywords: 2-(benzylideneamino)-ethanesulphonic acid, cadmium determination, taurine, benzaldehyde, spectrophotometry