Synthesis, characterization and thermal behavior on solid tartrates of light trivalent lanthanides
Solid state Ln–L compounds, where Ln stands for light trivalent lanthanides (L–Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration and thermal decomposition of the isolated compounds.
Thermal decomposition of lanthanum(III) butyrate in argon atmosphere
Abstract The thermal decomposition of La(C 3 H 7 CO 2 ) 3 · x H 2 O ( x  ≈ 0.82) was studied in argon during heating at 5 K/min. After the loss of bound H 2 O, the anhydrous butyrate presents at 135 °C a phase transition to a mesophase, which turns to an isotropic liquid at 180 °C. The decomposition of the anhydrous butyrate is associated to a solidification process. The final decomposition to La 2 O 3 takes place via two intermediate products: La 2 O(C 3 H 7 CO 2 ) 4 and La 2 O 2 CO 3 with release of CO 2 and the symmetrical ketone C 3 H 7 COC 3 H 7 .
Electrochemical detection of copper(II) at a gold electrode modified with a self-assembled monolayer of penicillamine
A penicillamine (PCA) self-assembled monolayer (SAM) was prepared on a gold electrode. It has been found that the modified electrode exhibited a selective response to copper ions. As demonstrated by cyclic voltammetric experiments, the SAM-based electrode showed an attractive ability to preconcentrate efficiently traces of copper(II) from solutions. Under optimum conditions, the anodic peak current was proportional to the concentration of Cu(II) in the range from 8.0 × 10−7 to 1.0 × 10−4 M with a detection limit of 4.0 × 10−7 M. Moreover, this modified gold electrode is also characterized by excellent repeatability, showing a relative standard deviation of 3.2% for nine successive measurements of 1.0 × 10−5 M Cu(II). The PCA/Au SAM gold electrode was used for the determination of Cu(II) in a tap water sample and the results showed a good agreement with the data obtained by atomic emission spectrometry.