The solubility dependence of Pu(0H) 4 as a function of the pn of diluted equilibrating perchloric acid solutions has been studied by covering a wide interval of ps-From the experimental solubility data obtained and some theoretical implications, an attempt has been made to conciliate the extrapolated, experimentally found thermodynamic solubility product with DEBYE-HUCKELS theory on ionic effects to account for the variations observed of the apparent solubility product throughout the different experiments carried out. The study of the apparent solubility product as a function of the ionic force has evidenced the existence of important discontinuities, which have been tentatively referred to a number of hypothesis based on the variation of the ionic activities of the present species, and on the impurities characterized in the precipitate systematically used as the starting material throughout this work. Some other interesting features of Pu (OH)! connected with this investigation have been studied in detail. Since the analysis of the precipitate employed has evidenced the presence of some percent amounts of plutonyl hydroxide, a study of the amphoteric characteristics of this species could be undertaken simultaneously. The method used for the calculation of the instability constant of the amphoteric process involved has been described in detail. A single ion-exchange experiment has been carried out with the aim of getting some information on the state of plutonium in very diluted aqueous solutions. Zusammenfassung Wir untersuchten in einem weiten ^Η-Bereich die Löslichkeit von Pu(OH) 4 in verdünnten HC10 4 -Lösungen. Die Variation des experimentellen Löslichkeitsprodukts sollte mit der DEBYE-HÜCKEL-Theorie in Einklang stehen. Das scheinbare Löslichkeitsprodukt zeigt, als Funktion der Ionenstärke, bedeutende Diskontinuitäten, die wir mit Veränderungen der Ionenaktivität der Verbindung und Verunreinigungen des als Ausgangsprodukt verwendeten Niederschlags zu erklären suchen. In diesem Zusammenhang wurden weitere Eigenschaften des Pu(OH) 4 untersucht. Da das Ausgangspräparat einige Prozent Pu(VI)-hydroxid enthielt, konnte gleichzeitig dessen amphoteres Verhalten untersucht werden ; das dabei benutzte Rechen verfahren wird ausführlich angegeben. Den Zustand des Plutoniums in sehr verdünnter wässeriger Lösung untersuchten wir in einem Ionenaustausch-Experiment. RésuméNous avons étudié la solubilité du Pu(OH) 4 , en fonction du pu, dans des solutions d'acide perchlorique. La variation du produit de solubilité expérimental devrait être en accordance avec la théorie de DEBYE-HUCKEL. La variation du produit de solubilité apparent en fonction de la force ionique comporte des discontinuités importantes, que nous essayons d'expliquer par les variations de l'activité ionique des espèces présentes, et par la présence d'impuretés dans le produit de départ. D'autres propriétés du Pu(OH) 4 ont été corrélativement étudiées en détail. Puisque le matériel de départ contenait quelques pour cent d'hydroxyde de Pu(VI), nous avons pu étu...

The synthesis of the electronic and infrared spectra of di-2-pyridyl ketone salicyloylhydrazone (DPKSH) and di-2-pyridyl ketone benzoylhy-drazone (DPKBH) is reported. Ultraviolet absorption spectra have been applied for determining the dissociation constants: DPKSH, pK1 = 3.5 and pK2 = 6.85; DPKBH, pK1 = 2.75 and pK2 = 10.6. These pK a values are interpreted as a function of the ortho-position of the OH group. Chelating properties of both tridentate ligands have been investigated. DPKSH forms a larger number of metal chelates in acidic media than does DPKBH. Also, it is concluded that DPKSH is a more suitable compound than DPKBH to preconcentrate and to determine heavy metal ion traces as it is inferred from the data obtained by flame AAS.

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Wine samples are extremely complex in their content of polyphenolic compounds; this necessitates an initial fractionation prior to their analysis by HPLC, to simplify the chromatograms obtained so that they can be reliably identified and quantified. Solid-phase extraction is one of the appropriate techniques for this purpose. This paper presents the work undertaken to devise a method of fractionating polyphenolic compounds in wine; this comprises a sequence of two stages: first, one of cleaning and preconcentration, using a reversed-phase C18 cartridge, and second, one of fractionation into two groups, acid and neutral polyphenols, using a SAX-type anionic exchanger. Both of these stages have been optimized, using standard solutions, to achieve maximum recovery and reproducibility.

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