Spectrophotometric determination of tellurium in trace quantities by use of an ion-association complex.
The formation of an ion-association complex by the interaction of iodotellurate(IV) with cetyltrimethylammonium bromide is used as the basis of an extractive procedure to determine tellurium in the range 2.5-12.5 mug in a final aqueous phase volume of 20 ml. The method is simple, reliable and sensitive. Selectivity is achieved by separation of tellurium on aluminium hydroxide as collector.
Trace determination of Tellurium using Liquid Scintillation and Cerenkov Counting
A sensitive and selective radiometric method for the determination of trace levels of tellurium is described. The method is based on the radiodisplacement of CdII from a bis(diethyldithiocarbamato)cadmium-115m(II) complex by TeIV at pH 3.3. The activity of the displaced radiocadmium, which is proportional to the amount of TeIV taken, was measured by liquid scintillation counting (LSC) and Cerenkov counting. The counting efficiency of LSC and Cerenkov counting was found to be 130% and 36%, respectively. The calibration graph was linear in the range 0.05–15 µg of tellurium in a final aqueous volume of 10 ml. The methods allowed the determination of tellurium at levels down to 0.05 µg for LSC and 0.1 µg for Cerenkov counting in a final volume of 40 ml. Quenching studies were carried out on the basis of the spectral index of the sample (SIS), which is a very sensitive quench indicating parameter, and the results clearly revealed the absence of colour and chemical quenching. The influence of foreign ions on the radiodisplacement reaction was studied and was easily eliminated by adopting an aluminium hydroxide collection procedure and by using proper masking agents. The method was successfully applied to the determination of tellurium in copper metal, copper concentrates, Sb–In alloy and cadmium oxide samples.
Clozapine derived 2,3-dihydro-1H-1,4- and 1,5-benzodiazepines with D4 receptor selectivity: synthesis and biological testing.
Novel 4-arylpiperazin-1-yl-substituted 2,3-dihydro-1H-1,4- and 1H-1,5-benzodiazepines and their aza-analogues were synthesized as debenzoclozapine derivatives for evaluation as potential D4-ligands. While Ki values of some of the title compounds came within the range of clozapine, they showed an impressively greater selectivity over other dopamine receptor subtypes, especially D2. For the most promising compounds, intrinsic activity and binding properties to serotonin 5-HT1A and 5-HT2 were also determined.