Abstract
A simple, rapid and accurate potentiolnetric method is described for tliedetermination of Os(VIII) in tlie co~icentrationr ange 0.4-4.0 mg/ml. Tlie method isbased on tlie addition of hydralazine hydrochloride to Os(VIII) to reduce it to Os(IV). The excess of hydralazine hydrocliloridew as oxidized by iodine dissolved ill acetic acid. The liberated iodide was then potentiometrically titrated against mercury(II) using silver amalgam as the indicator electrode. The potential of this method for sime- microdetermination is important in practical applications where tlie above reaction should proceed quantitatively towards completion. The relative standard deviation for six replicate deterinination of osmium(VIII) in binary andternary mixtures without the need for extraction or heating.
Highlights
The present study describes a new potentiometric method for the simetnicrodetermination of osiniuin by reduction with excess of liydralazine hydrocl~loride and oxidation the unreacted hydralazine hydrochloride irsi~ig iodine, the liberated iodide was titrated potentioinetrically with Hg(1I). 7'lie proposed tnethod has the advantage of being simple, rapid, accurate, precise, highly reproducible with reasonable selectivity, over conventional method
1- lletern~inationof osinium(VIIr) Aliquot of 2.0 1111 of 0.0105 M Os(VII1) solution was transferred from tlie microburette into a 100-in[1] Pyrex cell and 1.0 ml of2.0% HC1 was added and followed by 2.0-8.0 in[1] Of 0.0205 M hydralazine hydrochloride, tlie solution was left for about 2.0 inin to ensure complete reduction of Os(VII1) to Os(IV), wliich is sliown by transformation of the yellow to a brownish red colour, an excess of iodine solution was added and dissolved in acetic acid (43) of oxidise unreacted liydralazine hydrochloride and the liberated iodide was titrated witli 0.0385 M Hg(I1) [Fig. 11 as optimum titrant for highly change in potential at the end point
The proposed method depends essentially on adding to osinium(VII1) a known excess amount of liydralazine HCl, oxidizing unreacted liydralazine HCl with iodine dissolved in acetic acid and titrated the liberated iodide witli Hg(I1) using silver amalgam as the indicator electrode
Summary
It has been widely used for treatment of liypertetisioii It is act as reducing agent, and form coinplexes with inany metal ions (I). Khalifa et a1 '2', suggested a potentioinetric method for the determinatioii of osmiuin(VII1) usi~ig iodide. Roy et a1 '8' described a selective spectro-photometric method for the determinatiori of palladium and osiniuln in strongly acidic media using I-(l-naphthy1)-4,4,6-triinet11yllH, 4H-pyrimidine-2-tl~iol.Piizanowska et a1 '9) suggested a spectroplioto~netric tiietliod for the deter~nitiationof osmium(VII1) with proinazitle I~ydrochloi-idein acidic media. Popper et a1 ( I " determined os~niurn(VIIIp) l~otonletricallyin alkalitic solution with 2-etliyltliioisoiiicotiiia~i~ide. The present study describes a new potentiometric method for the simetnicrodetermination of osiniuin by reduction with excess of liydralazine hydrocl~loride and oxidation the unreacted hydralazine hydrochloride irsi~ig iodine, the liberated iodide was titrated potentioinetrically with Hg(1I). Osmium in synthetic binary and ternary mixtures of colnlnon lnetal ions that usually accoinpany os~niurnin nature and manufactured sa~nplesis determined by this method
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