Talanta
The development of a sensor for the direct and selective determination of atmospheric ethanol is in the initial stages. The sensor takes advantage of the selective chemical reaction between ethanol and vanadium oxinate. This reaction occurs in an organic medium where a red colored complex is the product. This reaction is determined spectrophotometrically where the absorbance maxima is 475 nm. The...
The partition of benzoic acid between 0.1M perchloric acid solution and two kinds of mixed solvents has been carried out at 25°C. The partition and dimerization constants of benzoic acid have been determined in the 1-octanol-benzene and 2-octanone-benzene systems. In both the mixed solvent systems, with increasing content of 1-octanol and 2-octanone in each mixed solvent, the partition constant...
Naphthalene-2,3-dicarboxaldehyde, 1-phenylnaphthalene-2,3-dicarboxaldehyde and anthracene-2,3-dicarboxladehyde have been characterized for use as fluorigenic reagents for the determination of primary amines and amino acids at the microgram level. The reaction conditions, spectral properties and the stability of the derivatives (isoindoles) have been investigated with standard amino acids. The results...
The uptake of cesium, strontium and europium from dilute nitric acid solutions by a poly(sodium acrylate-acrylic acid) PAA hydrogel has been investigated. pH variations are consistent with cation exchange processes: --COO - , Na + + , --COO - ,Na + m + (M m + = Cs + and Sr 2 + ) and--COOH 3 + . Saturation of the...
Two flow injection systems for the spectrophotometric determination of ascorbic actid at 245 nm have been described. On treatment with sodium hydroxide a fraction of the ascorbic acid was decomposed into substances, which do not absorb in UV region, and the decrease in signal measured. This was directly related to the amount of ascorbic acid present. The calibration graph was linear over the range...
The three overlapping pK a values ofN ,N ,N -tris[2-(3-hydroxy-2-oxo-1,2-dihydropyridin-1-yl)acetamido]ethylamin e, a tripodal hexadentate chelator formed from three 3-hydroxy-2(1H)-pyridinone moieties amide linked to tris-(2-aminoethyl)amine, were determined by simultaneous spectrophotometric and potentiometric titration. The data was analysed by non-linear regression with constraints...
The on-line solid phase extraction of trace amount of lead in flow-injection system with flame AAS detection was investigated using cellulose sorbents with phosphonic acid and carboxymethyl groups, C 1 8 sorbent non-modified and modified with Pyrocatechol Violet or 8-quinolinol, commercial chelating sorbents Chelex 100 and Spheron Oxin 1000, non-polar sorbent Amberlite XAD-2 modified with...
New iterative methods for analysis of potentiometric titration data of (a) mixtures of weak monoprotic acids with their conjugate bases, (b) solutions of polyprotic (di- and triprotic) acids, and (c) mixtures of two diprotic acids are presented. These methods, using data exclusively resulting from the acidic region of the titration curve permits the accurate determination of the analytical concentration...
An analytical method was developed for the determination of total dissolved selenium in fresh waters, using linear sweep cathodic stripping voltammetry (CSV) in combination with UV photolytic digestion. Both the CSV method, based on the electrodeposition and stripping of Cu 2 Se, and the UV irradiation procedure were investigated in detail. In the presence of dissolved organic substances,...
The neotetrazolium hexachloridorhenate(IV) (NTReCl 6 ) has been synthesized and its composition checked. The optimum conditions for the extraction of NTReCl 6 with dichloroethane have been established. The recovery factor for one-fold extraction is R = 74%. The distribution constant, K p , extraction constant, K e x , and ion-association constant, β, have been...
A method has been developed for the spectrophotometric determination of siderophores using flow-injection analysis (FIA) based on the reaction of siderophores with the ternary complex Eriochrome Cyanine R-Fe(III)-cetyltrimethylammonium bromide. 2,3-Dihydroxybenzoic acid, 2,3-dihydroxynaphthalene, and tolypocine were used as the model iron-binding ligands. The calibration curve for one of the siderophores...
A chemical separation method has been developed for the determination of 9 9 Tc in various types of radioactive wastes. Such a method includes (i) fusion with NaOH, (ii) extraction in a column containing methyltrioctylammonium chloride, (iii) extraction by solvent with N-benzoyl-N-phenylhydroxylamine and, (iv) measurement by inductively-coupled plasma mass spectrometry (ICP-MS). From...
In the present work we obtained the experimental pKs of the amino acid α-alanine in NaCl at 25° and different ionic strengths. The equilibrium constants have been potentiometrically determined with a commercial glass electrode and the results analysed through three models: two directly based on the Pitzer and Scatchard approaches to the ion specific interaction theory and the other based on a simpler...
A normal-phase high performance liquid chromatography using a 5-μm Spherisorb-CN column (250 4.6 mm i.d.) has been used for determination of the monomeric anthraquinones and their glycosides present in rhubarb roots, senna leaves and dock flower. The effects of various parameters were studied and the conditions for the extraction of the anthraquinones from herbal samples and their chromatographic...
The adsorptive stripping voltammetric determination of germanium(IV) based on the adsorptive accumulation of the germanium(IV)-pyrogallol complex on a hanging mercury drop electrode is reported. The reduction current of the adsorbed germanium complex is measured by differential-pulse cathodic stripping voltammetry. The peak potential is at -0.42 V vs. Ag/AgCl (saturated KCL). The effects of various...
The versatility of flow injection as a procedure for enhancing the performance of atomic spectrometry is demonstrated by the on-line separation and preconcentration of analyte ions of interest for methods employing atomic spectrometric measurements. In this paper, a sensitive method for the determination of palladium by flame atomic absorption spectrometry associated on-line with the flow injection...
A new commercial system consisting of a flow injection analysis system for hydride generation coupled with a transversely heated graphite atomizer-atomic absorption spectrometer for the determination of lead is investigated in detail. The hydride generation is optimized by using an ammonium peroxodisulphate-hydrochloric acid system as oxidant and sodium borohydride as reducing reagent. The addition...
The transport of iron(III) using polyether-based polyurethane membranes was studied. The rate at which iron passes through the membrane depends on the formation of the HFeX 4 species, which is related to the initial acid and salt concentration of the metal solution. Iron is quantitatively transported from a cell of high acid-halide concentration to one with low concentration.
Four new sulfur-containing compounds based on pyridine, benzene, 1,8-naphthyridine and 1,10-phenanthroline have been synthesized. These molecules have been incorporated into a polymeric matrix as neutral carriers and evaluated as silver sensors. Two of the compounds (pyridine and benzene) show high selectivity for Ag + . The sensor with the pyridine-based compound, in particular, shows...
A trace level of Se was collected on activated carbon (AC) as the Se(IV)-3-phenyl-5-mercapto-1,3,4-thiadiazole-2(3H)-thione (Bismuthiol II) complex. The AC was directly introduced as an AC-suspension into the graphite tube atomizer and the Se concentration was determined by atomic absorption spectroscopy (T. Okutani, T. Kubota, N. Sugiyama and Y. Turuta, Nippon Kagaku Kaishi, (1991) 375). The amount...