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111.
M. Houshmand A. Jabbari H. Heli M. Hajjizadeh A. A. Moosavi-Movahedi 《Journal of Solid State Electrochemistry》2008,12(9):1117-1128
The electrocatalytic oxidation of aspirin and acetaminophen on nanoparticles of cobalt hydroxide electrodeposited on the surface
of a glassy carbon electrode in alkaline solution was investigated. The process of oxidation and the kinetics have been investigated
using cyclic voltammetry, chronoamperometry, and steady-state polarization measurements. Voltammetric studies have indicated
that in the presence of drugs, the anodic peak current of low valence cobalt species increases, followed by a decrease in
the corresponding cathodic current. This indicates that drugs are oxidized on the redox mediator which is immobilized on the
electrode surface via an electrocatalytic mechanism. With the use of Laviron’s equation, the values of anodic and cathodic
electron-transfer coefficients and charge-transfer rate constant for the immobilized redox species were determined as α
s,a = 0.72, α
s,c = 0.30, and k
s = 0.22 s−1. The rate constant, the electron transfer coefficient, and the diffusion coefficient involved in the electrocatalytic oxidation
of drugs were reported. It was shown that by using the modified electrode, aspirin and acetaminophen can be determined by
amperometric technique with detection limits of 1.88 × 10−6 and 1.83 × 10−6 M, respectively. By analyzing the content of acetaminophen and aspirin in bulk forms using chronoamperometric and amperometric
techniques, the analytical utility of the modified electrode was achieved. The method was also proven to be valid for analyzing
these drugs in urine samples. 相似文献
112.
An on-line solid phase extraction method, linked to inductively coupled plasma optical emission spectrometry (ICP-OES), has been examined using octadecyl-bonded silica cartridge for determination of low levels of uranium and thorium in aqueous
samples. 2,3-dihydro-9,10-dihydroxy-1,4-anthracenedion forms a hydrophobic complex with cations and the resulted complex was
retained on SPE. The retained complex was eluted using an acidic solution and introduced into ICP for determination. Various
effective parameters and chemical variables such as sample pH, amount of ligand (as a complexing agent), sampling and eluting
flow rates and concentration of the eluent were optimized. Under optimal conditions, calibration curves with dynamic linear
ranges of 1–200 μg/L (r
2 = 0.9999) and 1–500 μg/L (r
2 = 0.9994) for U and Th were obtained, respectively. Detection limits based on three times of standard deviations of blank
by 6 replicates were 0.69 μg/L and 0.84 μg/L for U and Th, respectively. Sample throughput was 10 samples/h. The interference
effects of several metal ions on percentage of recovery of U and Th were also studied. The method was applied to the recovery
and sequential determination of these actinide elements in different water samples. 相似文献