Development of an optode for detection of trace amounts of Hg2+ in different real samples based on immobilization of novel tetradentate Schiff bases bearing two thiol groups in PVC membrane.

A very sensitive and reversible optical chemical sensor based on a novel tetradentate Schiff base namely N.N(/)bis(2-aminothiophenol)benzene-1,2-dicarboxaldehyde (ATBD) immobilized within a plasticized PVC film for Hg(2+) determination is described. At optimum conditions (i.e. pH 6.0), the proposed sensor displayed a linear response to Hg(2+) over 1.0 × 10(-10) - 1.0 × 10(-2) mol L(-1) with a limit of detection of 7.23 × 10(-11) mol L(-1) (0.0145 µgL(-1)). Moreover, the results revealed that, under batch condition, the sensor is fully reversible within a response time ~ 35 s. In addition to its high stability and reproducibility, the sensor showed good selectivity towards Hg(2+) ion with respect to common metal cations. The sensor was successfully applied for determination of Hg(2+) ion in some real samples, including hair, urine and well water samples. The results were in good correlation with the data obtained using cold vapor atomic absorption spectrometry.

Vibrational and thermal studies of the complexes (NH4)[VO(O2)2(phen)].2H2O and (NH4)[V(O2)3(phen)].2H2O.

The infrared spectra of the oxodiperoxo and triperoxo complexes, (NH4)[VO(O2)2(phen)].2H2O and (NH4)[V(O2)3(phen)].2H2O have been recorded and the observed bands are assigned on the basis of Cs symmetry. Thermogravimetric (TG) and differential thermal analysis (DTA) measurements on these two complexes were also carried out. A detailed mechanism for the mode of thermal decomposition of the two complexes has been given and supported by infrared spectral measurements on the thermal decomposition products. The data obtained agree quite well with the expected structure and indicate that the final thermal decomposition product of these two complexes is V2O5.