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1.
A liquid chromatography-mass spectrometry method for the determination of the coccidiostats metronidazole, ronidazole, dimetridazole,
secnidazole, tinidazole and ipronidazole in feedstuff was developed. The 5-nitroimidazoles were extracted from animal feed
with a pH 2 phosphate buffer solution followed by a solid phase extraction procedure based on HLB cartridges. The liquid chromatographic
separation of the extracts was performed on a C18 bonded silica column applying a gradient of elution with pH 4.3 ammonium acetate buffer solution and acetonitrile. Quantification
for each 5-nitroimidazole was carried out monitoring its molecular ion [M + H]+ obtained by positive electrospray ionisation mode. A pool of feedstuffs was used to optimise and validate the method. Linearity,
quantification limit, intra-day and inter-day reproducibility and accuracy were estimated using this pool of feedstuffs spiked
with the drugs. For the confirmatory assay, several fragment ions from each 5-nitroimidazole were obtained and monitored.
The method was applied successfully to determine 5-nitroimidazoles in feedstuff at level of 0.05 mg kg−1. 相似文献
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A cationic exchanger paper is used to retain analytes in solution and, after drying, to analyze directly by measuring the UV-Vis absorbance of the paper. The method was applied to determination of iron using its known 1,10-phenanthroline complex. Using 100 ml of sample the applicable concentration range was between 1.0 and 10.0 ng/ml with a detection limit of 0.2 ng/ml and a RSD around 2%. The method was applied to determination of iron total in snow, human serum and wine. 相似文献
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Oscar Cervantes Zaira del Rocio Lopez Norberto Casillas Peter Knauth Nayeli Checa Francisco Apolinar Cholico Rodolfo Hernandez-Gutirrez Luis Hector Quintero Jose Avila Paz Mario Eduardo Cano 《Molecules (Basel, Switzerland)》2022,27(2)
A ferrofluid with 1,2-Benzenediol-coated iron oxide nanoparticles was synthesized and physicochemically analyzed. This colloidal system was prepared following the typical co-precipitation method, and superparamagnetic nanoparticles of 13.5 nm average diameter, 34 emu/g of magnetic saturation, and 285 K of blocking temperature were obtained. Additionally, the zeta potential showed a suitable colloidal stability for cancer therapy assays and the magneto-calorimetric trails determined a high power absorption density. In addition, the oxidative capability of the ferrofluid was corroborated by performing the Fenton reaction with methylene blue (MB) dissolved in water, where the ferrofluid was suitable for producing reactive oxygen species (ROS), and surprisingly a strong degradation of MB was also observed when it was combined with H2O2. The intracellular ROS production was qualitatively corroborated using the HT-29 human cell line, by detecting the fluorescent rise induced in 2,7-dichlorofluorescein diacetate. In other experiments, cell metabolic activity was measured, and no toxicity was observed, even with concentrations of up to 4 mg/mL of magnetic nanoparticles (MNPs). When the cells were treated with magnetic hyperthermia, 80% of cells were dead at 43 °C using 3 mg/mL of MNPs and applying a magnetic field of 530 kHz with 20 kA/m amplitude. 相似文献
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Daniele Passarella Sergio Riva Gabriele Grieco Francesco Cavallo Begoña Checa Federica Arioli Elena Riva Daniela Comi Bruno Danieli 《Tetrahedron: Asymmetry》2009,20(2):192-197
The convenient synthesis of both enantiomers of the piperidine alkaloids such as dumetorine and epidihydropinidine is described. Pure enantiomers of 2-(2-hydroxy-ethyl)-piperidine-1-carboxylic acid tert-butyl ester are used as a common starting material. The syntheses are based on a RCM reaction and on methylation of the piperidine ring according to Beak–Lee methodology, respectively. 相似文献
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Francisco Bosch Reig Amparo Checa Moreno Marina Barbas Pardillo Vicente Peris Martinez Jose V. Gimeno Adelantado 《Mikrochimica acta》1989,99(1-2):49-57
A method is proposed for determination of fluoride by separation in acid medium followed by ion-selective electrode measurement. The separation is done at temperatures up to 200 °C, without any previous treatment of the sample, in a PTFE reactor designed to ensure the complete absorption of volatile fluoride compounds. The distillation variables (temperature, time and acid concentration) have been optimized and the interference of other various species in the separation step has been studied. The method has been applied to geological samples. The results obtained are statistically satisfactory. 相似文献
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Liquid chromatography-mass spectrometry has become a powerful analytical tool, with high selectivity and sensitivity. Usually in this technique, the calibration function is estimated from the molecular peak signal. This report describes the improvement in sensitivity when the signals from several fragments in addition to the molecular peak are used to establish the calibration function. The influence of the dwell time has also been analysed as an important instrumental parameter that influences the signal range, and consequently, the sensitivity. The calibration function obtained by adding fragment signals was used to estimate the instrumental detection limit using three different procedures, comparing and discussing the results obtained. 相似文献
10.
Aggregation and Contingent Metal/Surface Reactivity of 1,3,8,10‐Tetraazaperopyrene (TAPP) on Cu(111)
Manfred Matena Meike Stöhr Dr. Till Riehm Dr. Jonas Björk Susanne Martens Matthew S. Dyer Dr. Mats Persson Prof. Jorge Lobo‐Checa Dr. Kathrin Müller Dr. Mihaela Enache Hubert Wadepohl Prof. Jörg Zegenhagen Dr. Thomas A. Jung Dr. Lutz H. Gade Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(7):2079-2091