A sensitive chemiluminescence method for the determination of H2O2 in exhaled breath condensate.
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In this paper, a novel flow injection chemiluminescence (FI-CL) method is proposed for the determination of picomolar L(-1) levels of hydrogen peroxide (H(2)O(2)) in exhaled breath condensate (EBC). This method is based on the oxidation of a low concentration of luminol (10(-7) M) by H(2)O(2) at a low concentration level (< 10(-8) M) in an alkaline medium catalyzed by a complex, K(5)[Cu(HIO(6))(2)] (DPC), which is not interfered by other metal ions or horseradish peroxidase (HRP). Under the optimum conditions, H(2)O(2) was determined over the range of 1.0 x 10(-10) to 1.0 x 10(-8) mol L(-1) with a detection limit of (3sigma) of 4.1 x 10(-11) mol L(-1). The relative standard deviation (RSD) was 3.2% for 5 nmol L(-1) H(2)O(2) (n = 7). The proposed method offers the advantages of ultra-sensitivity, selectivity, simplicity and rapidity for H(2)O(2) determination. It was successfully applied to directly determine trace amounts of H(2)O(2) (nmol L(-1)) in human's EBC of both rheum and healthy volunteers. A statistically significant difference was found between patients with rheum (n = 11) and control subjects without rheum (n = 11). (+info)
Decreased visual function after patchy loss of retinal pigment epithelium induced by low-dose sodium iodate.
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On-line vapor-phase generation followed by Fourier-transform infrared spectrometry for the quantitative analysis of water-soluble penicillin G in pharmaceutical formulations.
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The combination of vapor-phase generation (VPG) and Fourier-transform infrared (FTIR) spectrometry was performed as an alternative analytical technique for the determination of water-soluble penicillin G (PENG). Samples were transferred into a heated reactor, and a potassium iodate solution was injected into the reactor. Carbon monoxide (CO) generated under these conditions was carried via a N(2) gas carrier stream inside the IR gas cell, and the corresponding FTIR spectra were continuously recorded as a function of time. Analytical measurements were made using the maximum absorbance of the CO band at 2170 +/- 4 cm(-1). Various factors influencing the analytical signals were evaluated and selected. The figures of merit of the proposed method involve a linear calibration curve over the range of 3 to 320 mg L(-1), a limit of detection of 0.5 mg L(-1) and a precision of 2.6%. The method was successfully applied to PENG determination in pharmaceutical preparations. (+info)
Sodium iodate selectively injuries the posterior pole of the retina in a dose-dependent manner: morphological and electrophysiological study.
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Electrochemical determination of nitrite and iodate based on Pt nanoparticles self-assembled on a chitosan modified glassy carbon electrode.
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A promising electrochemical sensor was fabricated by the self-assembling of Pt nanoparticles (nano-Pts) on a chitosan (CS) modified glassy carbon electrode (GCE). A field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM) and electrochemical techniques were used for characterization of these composites. It has been found that nano-Pts are inserted into the CS layer uniformly, and have a larger surface area compared to the chitosan modified glassy carbon electrode. Electrocatalytic experiments for the oxidation of nitrite and the reduction of iodate have shown that nano-Pts/CS/GCE can decrease the over-potential and increase the faradic current, which can be used for the sensitive determination of nitrite and iodate. Moreover, the prepared modified electrode exhibits good reproducibility and stability, and it is possible that this novel electrochemical sensor can be applied in the sensing and/or biosensing field. (+info)