ABSTRACT
Two simple and sensitive kinetic-fluorometric methods have been developed for the determination of lanthanum(III): fluorescence quenching generated by the oxidation of safranine T or phenosafranine with potassium bromate in an acetate buffer solution. The rate of the oxidation reaction is significantly accelerated after adding lanthanum(III). A good linearity between the relative fluorescence intensity and lanthanum(III) is observed in the range of both 0.04 - 2.0 and 4.0 - 16 µg/mL. The detection limits have been 3.6 × 10-3 and 0.334 µg/mL respectively. The accuracy and reliability of the methods are further validated by recovery studies via a standard-addition method, with percentage recoveries ranging from 98 to 102%. Comparing the results of two measured reaction systems, we find that the safranine T reaction system provides high sensitivity and a wider linear range. In consequence, we have chosen the safranine T system to detect sample water, and explored the reaction mechanism.
ABSTRACT
A multi-walled carbon nanotubes (MWNTs) bridged mesocellular graphene foam (MGF) nanocomposite (MWNTs/MGF) modified glassy carbon electrode was fabricated and successfully used for simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (TRP). Comparing with pure MGF, MWNTs or MWNTs/GS (graphene sheets), MWNTs/MGF displayed higher catalytic activity and selectivity toward the oxidation of AA, DA, UA and TRP. Under the optimal conditions, MWCNs/MGF/GCE can simultaneously detect AA, DA, UA and TRP with high selectivity and sensitivity. The detection limits were 18.28 µmol L(-1), 0.06 µmol L(-1), 0.93 µmol L(-1) and 0.87 µmol L(-1), respectively. Moreover, the modified electrode exhibited excellent stability and reproducibility.
Subject(s)
Ascorbic Acid/analysis , Dopamine/analysis , Nanocomposites/chemistry , Tryptophan/analysis , Uric Acid/analysis , Ascorbic Acid/chemistry , Dopamine/chemistry , Electric Conductivity , Electrochemical Techniques , Electrodes , Graphite/chemistry , Hydrogen-Ion Concentration , Nanotubes, Carbon/chemistry , Reproducibility of Results , Surface Properties , Tryptophan/chemistry , Uric Acid/chemistryABSTRACT
The hexaaza macrocyclic copper(II) complex Cu(II)L(L=1,8-Dihydroxyethyl-1,3,6,8,10,13-hexaazacyclotetradecane), which has octahedral structure similar to some natural complexes, is synthesized and purified. In this study, oxidative breakage DNA by the reaction of Cu(II)L with H2O2 and ascorbate has been investigated by gel electrophoresis experiments. In electrochemical experiments, the on scDNA-modified glassy carbon electrode(GCE) is cleaved by the Cu(II)L and redox changing of the metal catalyst without adding any other reagents. Above all, the need for concentration of scDNA is much lower than that of gel electrophoresis experiments and the process of the performance is easy. Furthermore, Cyclic Voltammetry (CV) and A.C. Impedance, which are performed to monitor scDNA cleavage at the scDNA-modified glassy carbon electrode (GCE), are fast, simple and highly efficient. The mechanism of the damage can be suggested: Fenton.
Subject(s)
Copper/chemistry , DNA, Superhelical/chemistry , Macrocyclic Compounds/chemistry , Organometallic Compounds/chemistry , Ascorbic Acid/chemistry , Carbon/chemistry , Catalysis , DNA Damage , DNA, Superhelical/drug effects , Electrochemistry , Electrodes , Hydrogen Peroxide/chemistry , Macrocyclic Compounds/chemical synthesis , Macrocyclic Compounds/pharmacology , Molecular Structure , Organometallic Compounds/chemical synthesis , Organometallic Compounds/pharmacology , Oxidation-ReductionABSTRACT
The title copper(I) complex, [CuCl(C(11)H(14)N(2)O(3)S)(2)], was synthesized by the redox reaction of cupric chloride with the corresponding thiourea derivative as reducing agent. The Cu(I) coordination environment is trigonal planar, involving two S atoms and one Cl atom. The presence of intramolecular hydrogen bonds leads to the formation of a cis conformation and promotes the stability of the complex.
