PubMed · 8487829
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J D Snyder. 1993-06-10. Can bismuth improve the simple solution for diarrhea?. https://doi.org/10.1056/nejm199306103282309
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A method for the determination of bismuth in pharmaceutical products using methyltriphenylphosphonium bromide as a molecular probe based on the resonance light scattering (RLS) technique was developed. In the presence of Tween-20, bismuth reacts with a large excess of I(-) to form [BiI(4)](-), which further reacts with methyltriphenylphosphonium bromide (MTPB) to form an ion-association compound. This resulted in a significant enhancement of RLS intensity and the appearance of the corresponding RLS spectral characteristics. The enhanced RLS intensity was directly proportional to the concentration of Bi(III) in the range of 0.001-1.50 microg/ml for the system. The detection limit was 0.98 ng/ml. The characteristics of RLS spectra of the complex, the optimum conditions and the influencing factors were investigated. The method has high selectivity and was applied to the determination of Bi(III) in pharmaceutical products with satisfactory results, which were in agreement with those of the official method and atomic absorbance spectrometry (AAS).
A simple, rapid, sensitive and reproducible spectrophotometry for determination of ultra trace organophosphorus pesticides (OPs) with liquid core waveguide light intensity technique is presented. OPs were degraded into phosphate with UV light, potassium peroxydisulphate as oxidant and nanosized titanium dioxide as catalyst. Under the optimum selected conditions, linear light intensity response was obtained in the range of 2.0 x 10(-11) to 8.0 x 10(-10)g mL(-1) phosphate, and the limit of detection (LOD) 6.7 x 10(-12)g mL(-1) was achieved. Both the low limit of linear range and the LOD of the proposed method were lower over 1000-fold than that of classical spectrophotometry. The proposed method was applied to the determination of ultra trace OPs in vegetables and fruits samples.
The absorption and upconversion fluorescence spectra of a series of Er3+/Yb3+-codoped xBi(2)O(3)-(90-x)GeO2-10Na(2)O (BGN x, x=31, 36, 41, 46 and 51 mol%) glasses have been studied. Intense green and red emission bands at around 533, 548 and 659 nm, corresponding to the 2H(11/2)-->4I(15/2), 4S(3/2)-->4I(15/2) and 4F(9/2)-->4I(15/2) transitions of Er3+, respectively, were simultaneously observed at room temperature. The dependence of intensities of upconversion emission on excitation power and possible upconversion mechanisms were evaluated and analyzed. The important role of Bi(2)O(3) in upconversion intensity is observed and its influence on the green (533 and 548 nm) and red (659 nm) emissions is compared and discussed. The influence of Bi(2)O(3) on the upconversion emissions has been investigated based on the IR spectra.