The fabrication of potentiometric membrane sensors and their applications

Abstract

Ionophore-incorporated PVC-membrane sensors are well-established analytical tools routinely used for the selective and direct measurement of a wide variety of different ions in complex biological and environmental samples. The key ingredient of such plasticized PVC-members is the involved ionophore, defining the selectivity of the electrodes complex formation with the cation of interest. In the past few years, the development of new ion-selective electrodes for various ions has been reported in the literature.

Synthesis, Characterization and Antibacterial Activity of New Complexes of Some Lanthanide Ions with 15-Crown-5 and 18-Crown-6

“…The appearance of this new peak which was absent in the spectrum of the ligand gives a great indication for the complex formation and may lead to the conclusion that the picrate ions were somehow incorporated in the skeleton of the complex. This conclusion was confirmed by the 13 C-NMR spectra of the complexes, in which both complexes showed three singlet peaks, the first peak at ä (125 ppm) which corresponds to the two aromatic carbons attached to the hydrogens 3 of the benzene ring of picrate ion 31 , the second peak at ä (142 ppm) which corresponds to the three carbon atoms attached to the nitro groups (C-NO 2 ) 31 , and the third peak at ä (161.60 ppm) which was attributed to the carbon atom attached to the phenolic oxygen 31,39 . These peaks or signals are characteristic of the picrate anion.…”

“…The IR spectra were recorded using KBr pellets and a 8400 S -FTIR SHIMADZU spectrometer. The 1 H-NMR and 13 C-NMR spectra of some of the ligands and their complexes were recorded in DMSO using a fourier transform Ultra Shield 300 MHz spectrometer, Bruker company, origin: Switzerland, with tetramethyl silane as internal standard. The UV -Visible Spectra were recorded using a 1800 -UV SHIMADZU spectrometer.…”

“…The peaks or signals assigned to the (C-O-C) ether carbons also experienced a simple shift confirming the interaction between the metal ions and the ligands 33,36,38 . The data of the (11) and (12) show the 13 C-NMR spectra of 18-crown-6 and its Nd 3+ complex respectively.…”

“…They are also used in electronic and optical devices 8 , in molecular recognition and transport of organic ammonium derivatives such as amines, amino acids, and related compounds (obviously in protonated state) 9,10 , as antifungal agents 11 , removal of the highly toxic and harmful heavy metal ions 12 , as sensors 13,14 , corrosion inhibitors 15 and they are also used widely in extraction processes [16][17][18] due to their binding selectivity. The coordination chemistry of the lanthanides with crown ethers has been extensively studied [19][20][21][22] , due to their importance in biological, biochemical, medical and many other applications such as an excellent diagnostic and prognostic probe in clinical diagnostics 8 , an anticancer material 4,9 , lanthanide complexes based X-ray contrast imaging and lanthanide chelates based contrast enhancing agents for Magnetic Resonance Imaging (MRI) 11 are being excessively used in radiological analysis in our body systems [9], also as shift reagents for NMR spectrometry [10][11][12] , as well as, their potential applications in fundamental and applied science such as organic synthesis, bioorganic chemistry and homogeneous catalysis [11][12][13] . The chemistry of lanthanides differs significantly from the chemistry of main group and transition metal elements because of the 4 f orbitals that are spatially 'buried' inside the atom and are shielded from the ligand field.…”

“…H-NMR, 13 C-NMR and UV-Visible spectrophotometric methods, thermal analysis (TGA & DTG), magnetic susceptibility , molar conductance and melting points. Also an in-vitro study on pathogenic gram positive (Staphylococcus aureus) and pathogenic gram negative bacteria (Escherichia coli, Salmonella and pseudomonas aeruginosa) was performed and the results were compared to those of a broad spectrum antibiotic (Chloramphinicol).…”