Determination of Microgram Amounts of Thorium

Spectrophotometric determination of thorium in standard samples and monazite sands based on the floated complex of thorium with N-hydroxy-N,N′-diphenylbenzamidine and thorin

“…The following diverse ions do not interfere in the determination of 15 pg Th(IV) 10 ml -': Fluoride, Zr4+ U4 + , F.e 3+ , Pb2+ , Cu 2+ , V s+ , Ni 2+ , Cd2+ , Zn 2+ , Sn 2+ in the range (0.02-1.2).mg; Nb5+ Mo5+ W6, Re7+ Pd 2 + , Ga 2+ , A1 3+ , Sb 3+ , Co 2+ , Cr3+ Hg2+, Mn z+ , Mgz + in the range (3.5-8.0) mg; acetate, tartrate, oxalate, thiourea, ascorbic acid in the range (15.0-20.0) mg. Fe(III) interferes when present in a 30-fold excess. However, its reduction-to Fe(II) by ascorbic acid (1 ml, 2%) increases the tolerable amount up to 0.8 mg. Interferences due to U(IV) and Zr(IV) were avoided by oxidation of U(IV) to U(VI) with perchloric acid [10] and masking with tartaric acid (0.2 ml, 10%), respectively.…”

“…Many spectrophotometric methods for the determination of thorium have been reported, using various reagents and dyes such as 2-hydroxy-l-naphthaldehyde-iso-nicotinoylhydrazone [1], N-phenylbenzohydroxamic acid [2], 4-methoxy-2'-chlorodibenzoylmethane [3], molybdothorophosphoric acid [4], 4-(2-pyridylazo) resorcinol [5], aniline blue [6], catechol violet [7], eriochrome cyanine R [8], gallein [9], thorin [10], and others [11]. But most of these methods are tedious, need rigid control of pH, temperature and reagents, and are not selective as most of the common ions and anions associated with Th(IV) interfere.…”

THE USE OF TRI-n-OCTYLPHOSPHINE OXIDE IN THE SOLVENT EXTRACTION OF THORIUM FROM ACIDIC SOLUTIONS

“…The degree to which thorium was distributed between the two phases was usually established through the determination of the thorium that remained in the aqueous phase. Test portions of the aqueous phase were removed by pipet and the concentration of thorixjm was determined (6) by the gravimetric oxalate or spectrophotometric Thorin methods. The concentration of thorium in the organic phase was subsequently calculated by difference.…”

La détermination de la température optimale de précipitation de l'iodate de thorium

“…Les mtthodes de determination analytique du thorium dans les minerais et les produits mttallurgiques thoriferes sont assez nombreuses et leur choix dtpend de multiples facteurs tels que la prtcision dtsirte, l'importance de la teneur, la nature et l'importance des autres tltments, la rapiditt tventuellement exigte, le prix des appareillages ntcessaires (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Les proctdts les plus courallts sont la gravimttrie par l'iodate ou par le thiosulfate (I, ll), la titrimttrie par le molybdate ou l'oxinate, la colorimttrie par l'acide arsCnophCnylazonaphtol-disulfonique (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), la fluorimttrie par l'amino-hydroxyanthraquinone (12), la spectrophotomttrie par l'acide dimtthyl aminophtnylarsinique (2,4), la fluorescence, la polarographie et l'analyse spectrale (1, 7, 1 l), la complexomttrie (8,9), l'tchange ionique et l'extraction liquide-liquide (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”

“…Les proctdts les plus courallts sont la gravimttrie par l'iodate ou par le thiosulfate (I, ll), la titrimttrie par le molybdate ou l'oxinate, la colorimttrie par l'acide arsCnophCnylazonaphtol-disulfonique (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), la fluorimttrie par l'amino-hydroxyanthraquinone (12), la spectrophotomttrie par l'acide dimtthyl aminophtnylarsinique (2,4), la fluorescence, la polarographie et l'analyse spectrale (1, 7, 1 l), la complexomttrie (8,9), l'tchange ionique et l'extraction liquide-liquide (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”