Flow injection analysis : Part VI. The determination of phosphate and chloride in blood serum by dialysis and sample dilution

The rapid determination of chloride and inorganic phosphate in blood serum based on continuous flow spectrophotometry was adapted to Flow Injection Analysis by applying dialysis as well as differential dilution of the injected samples. In addition to the manual injection procedure, an automated microsampling unit was developed and used. By continuous dialysis, chloride could be determined reproducibly at a sampling rate of 125 samples per hour at sample volumes of 60 μl or less. A similar sampling rate and high precision were obtained for the determination of inorganic phosphate by using differential dilution.     

Observation of a Doppler broadening of the 4438 keV gamma-line of12C in processes12C(n,n′γ)12C and9Be(α, nγ)12C

A Doppler broadening is described of the 4438 keV spectral gamma-line observed by means of a Ge(Li) detector during the deexcitation of nuclei of¹²C in an inelastic scattering¹²C(n, n′γ)¹²C using an²⁴¹Am−Be source as well as during the reaction⁹Be(α, nγ)¹²C taking place in the Am−Be source. The FWHM of the spectral line is equal to (90±4) keV in the latter reaction and (64±8) keV in the former process. Experimental values agree well with theoretical ones. Presented at the Instrumental Activation Analysis Conference, IAA 79, June 4–8, 1979, Klučenice, Czechoslovakia.     

Flow injection analysis. principles,applications and trends

The basic principles of Flow Injection Analysis are outlined. The parameters governing the dispersion of the injected sample zone in the system are discussed, and it is demonstrated how these parameters can be manipulated in order to suit the requirements of an individual analytical procedure. A number of examples illustrating the practical application of f.i.a. are described, comprising the use of automated, stopped-flow, merging-zones, extraction techniques as well as f.i.a. scanning and methods based on intermittent pumping. Updated lists on f.i.a. procedures published and species that can be determined by f.i.a. are included.     

Stereochemistry of cyclic ether formation—II : Intramolecular cyclisation of secondary aliphatic alcohols to tetrahydrofuran-type ethers

The mechanism and stereochemistry of δ-C atom functionalisation in the reactions of secondary straight-chain aliphatic alcohols with lead tetraacetate, ceric ammonium nitrate, and heavy metal (Pb⁴⁺, Hg²⁺, Ag⁺) salts (AcO)^?1, O^2?, CO₃^2?-halogen (I₂, Br₂, Cl₂) combinations are discussed. By demonstrating the intermediacy of 5-bromo-2-hexanol, it was confirmed that the dark silver oxidebromine induced cyclisation of 2-hexanol (and alcohols in general) involves (as the other hypohalite reactions) intramolecular 1,5-hydrogen abstraction by alkoxy radicals and formation of δ-bromohydrins. A novel and simple procedure for obtaining tetrahydrofurans from alcohols by way of the hypochlorite reaction, using silver or mercuric salts and chlorine, is described.     

Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Synthesis of fused imidazo-pyridine and -azepine derivatives by sequential van Leusen/Heck reactions

Fused imidazo-pyridine and -azepine derivatives were synthesized using a sequential van Leusen/intramolecular Heck protocol. The combination of a multicomponent reaction followed by an intramolecular carbon-carbon bond forming reaction generates heterocycles of significant molecular complexity from readily available starting materials in just two steps.     

Comparison of the Temperature Effect on the π∗←n and π∗←π Electronic Transition Bands of NO<Subscript>3</Subscript><Superscript>−</Superscript>(aq)

The effect of temperature on the π∗←π transition band in the UV absorption spectrum of NO₃⁻(aq) centered at ≈200 nm was studied in the temperature range 10–70 ^∘C. The observed temperature independence of this band was in contrast to the significant influence of temperature on the nitrate π∗←n transition reported recently by us. However, taking into account the electronic states involved in both the transitions, it was concluded that this finding was in accordance with our previous assumption that interconversion between spectrally distinct (with respect to π∗←n band) nitrate species included the rupture/formation of hydrogen bond(s) in the hydration shell of the nitrate ion.     

Conductivity Studies of Dilute Aqueous Solutions of Oxalic Acid and Neutral Oxalates of Sodium, Potassium, Cesium, and Ammonium from 5 to 35°C

Conductivity measurements of oxalic acid and neutral oxalates (disodium oxalate, dipotassium oxalate, dicesium, and diammonium oxalate) were performed on dilute aqueous solutions, c < 3 × 10^–3 mol-dm^–3, from 5 to 35°C. These data and those available from the literature were analyzed in terms of dissociation steps of oxalic acid, the Onsager conductivity equation for neutral oxalates, the Quint–Viallard conductivity equation for the acid, and the Debye–Hückel equation for activity coefficients, to give the limiting equivalent conductances of bioxalate anion ;(HC₂O₄ ^–) and oxalate anion (1/2C₂O₄ ^2–) and the corresponding dissociation constants K ₁ and K ₂.     

Interactions of proteins with uniform colloidal hematite and chromium hydroxide particles. I. Adsorption

The adsorption of ovalbumin, -globulin, and lysozyme on uniform spherical hematite and chromium hydroxide particles in aqueous media has been studied as a function of the pH at a constant ionic strength. The uptake of ovalbumin and -globulin was greatest at their isoelectric points and differed little at 10^–2 and 10^–3 mol dm^–3 NaNO₃. The adsorption of lysozyme was strongly influenced by the ionic strength.The deposition of ovalbumin on hematite in the presence of Mg (NO₃)₂ was significantly greater than that with NaNO₃ under otherwise comparable conditions. Dialysis experiments with ovalbumin against magnesium nitrate solutions showed Mg²⁺ to be specifically bound to the protein.The shapes of isotherms indicated monolayer coverage for ovalbumin and multilayer coating for lysozyme for both adsorbents. The shapes of isotherms of -globulin on hematite point to a rearrangement of the protein on the particle surface, while a monolayer was found on chromium hydroxide particles.Supported by the NSF Grant CHE-9108420Part of a Ph.D. thesis     

Influence of the pyridine methyl substituent position on the chemical changes of the NCS groups in the thermal decomposition of coordination compounds of the type Cu(NCS)2L2

The influence of the position of the CH₃ group in picoline and lutidine ligands on the degree of chemical change of the NCS groups in coordination compounds of the type Cu(NCS)₂L₂ (whereL=2-, 3- and 4-picoline, and 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-lutidine) is dealt with. The most marked effect of the CH₃ group is found to be exerted in position 4. This effect of the methyl group on the degree of chemical change points to the mutual influence of the ligands in coordination compounds of Cu(II).

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Zusammenfassung Der Artikel befaßt sich mit dem Einfluß der Lage der CH₃ Gruppe in Pikolinen und Lutidinen als Liganden auf den Grad der chemischen Änderungen der Gruppen NSC in Koordinationsverbindungen des Typs Cu(NCS)₂L₂ (L=2-, 3- und 4-Pikoline, 2,3-, 2,4-, 2,5-, 2,6-, 3,4- und 3,5-Lutidine). Der ausgeprägteste Effekt der CH₃ Gruppe wurde in der Position 4 beobachtet. Dieser Einfluß der Methylgruppe auf das Ausmaß der chemischen Änderungen deutet auch auf die gegenseitige Wirkung der Liganden in Koordinationsverbindungen von Cu(II).

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Résumé L'article a trait à l'influence de la position du groupe CH₂ dans les picolines et lutidines, en tant que ligands, sur le degré des changements chimiques des groupes SCN dans les composés de coordination du type Cu(SCN)₂L₂ (L=2-, 3 et 4-picoline, 2,3-, 2,4-,2,5-, 2,6-, 3,4- et 3,6-lutidine). L'effet le plus prononcé du groupe CH₃ s'observe en position 4. Cette influence du groupe méthyle sur le degré des changements chimiques indique aussi l'influence mutuelle des ligands dans les composés de coordination du Cu(II).

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- , , NCS Cu(NCS)₂,L₂, L=2-, 3- 4- , 2.3-, 2.4-, 2.5-, 2.6-, 3.4- 3.5-. , 4. Cu(II).