Indirect competitive immunoassay for trichlorophenol determination: Rational evaluation of the competitor heterology effect

An improved competitive indirect immunoassay for the detection of 2,4,6-trichlorophenol (2,4,6-TCP) has been developed and optimized by preparing heterologous haptens that have been evaluated as coating antigens. The relation between the degree of heterology and immunoassay detectability has been investigated according to the geometric and electronic distribution similarities between the haptens and the analyte using molecular modeling tools. The assay has been characterized according to different physicochemical parameters such as the incubation time, the ionic strength, the effect of detergents and the pH. The resulting assay has an IC₅₀ of 1.44 μg l⁻¹ and a limit of detection (LOD) of 0.2 μg l⁻¹ and it shows a good accuracy and suitability to analyze trichlorophenol in drinking water.     

Interactions of ammonium nitrate with different additives Thermodynamic analysis

In order to elucidate the influence of Ca and Mg carbonates with or without the presence of boron, manganese and copper compounds on the thermal stability of ammonium nitrate (AN), thermodynamic analysis of different reactions between AN and additives was carried out. Temperature dependency of Gibbs free energy changes ∆G _T and equilibrium composition of reaction products were calculated for a set of reactions using the HSC software. Main solid compounds that can form in the systems of AN and carbonates, were Ca(NO₃)₂ and Mg(NO₃)₂, Ca(OH)₂ and Mg(OH)₂, CaO₂ and MgO₂, CaO and MgO, and N-containing gaseous compounds NO, N₂O and NO₂. As a result of H₃BO₃, MnO₂ and CuSO₄ addition, the content of CuO, Cu₂O and MnO as solids and SO₂, SO₃ and HBO as gaseous reaction products reached the same level. Thereby, their equilibrium concentrations did not depend on the carbonate origin of CaCO₃, MgCO₃ or CaMg(CO₃)₂. Small amount of CuSO₄, H₃BO₃ or MnO₂ additive (0.01–0.05 mol) in the system, practically, did not influence the temperature dependencies of ∆G _T of the reactions between AN and CaCO₃ or CaMg(CO₃)₂. The influence of additives taken in the larger amount (0.5 mol) was evident and, depending on the additive and reaction, shifted their proceeding temperatures in either direction by more than 300–400 K.     

Compositional changes between free coatings and surface coating layers during mechanochemical process: An IR-based chemometric analysis

By mid-IR analysis, mixtures of stearic acid, a paraffinic compound and a fluorinated compound were analyzed using attenuated total reflection (ATR) spectroscopy and reflection-absorption infrared spectroscopy (RAIRS). The precision of the partial least square (PLS) models created for each of these two techniques were compared in order to work out a quality control process of the mixtures which are involved in mechanochemical coating technology. We obtained a good relationship between spectral data and concentration with ATR spectroscopy. However, RAIRS spectroscopy allows to observe the affinity of long-chain organic acids for steel surfaces, and to determine the actual composition of coatings.     

Nitroxydes—XLVII: Nitroxydes isoquinuclidiniques

5 and 7 substituted 1,3,3-trimethyl isoquinuclidines are prepared by the action of ammonia on piperitenone and 4-methyl piperitenone. Reduction of 1,3,3-trimethyl 5-isoquinuclidone, and the different alcohols obtained are described. The nitroxydes obtained by oxidation of these amines exhibit long range couplings.