Search results for "Spectrophotometry"
showing 10 items of 644 documents
Some observations on the use of matrix modifiers in the determination of aluminum by electrothermal atomic absorption spectrophotometry
1989
Abstract Some evidence demonstrating that the use of matrix modifiers is necessary to obtain good calibration lines in the determination of aluminum by graphite furnace atomic absorption spectrophotometry is provided. It was found that the most sensitive results were obtained when Mg(NO 3 ) 2 was used instead of NH 4 H 2 PO 4 .
Determination of platinum and iridium in reforming catalysts by second derivative and absorptiometric spectrophotometry
1991
Investigations on the spectrophotometric determination of platinum as a complex formed by tin(II)chloride in hydrochloric acid are reported. The determination of platinum was found to be interfered with by iridium, because it also forms a complex with tin(II) chloride. The features of the derivative absorption spectrophotometry for the quantitative determination of platinum and iridium was also studied. The analytical application of the method for the determination of platinum and iridium in catalysts was investigated.
Some observations on the spectrophotometric determination of nitrite using ergonovine-p-dimethylaminobenzaldehyde
1991
Abstract The system ergonovine maleate-p-diethylaminobenzaldehyde in sulfuric acid media is applied to the kinetic-spectrophotometric determination of nitrite ions with competitive precision. The reaction rate is strongly enhanced by the presence of nitrite or ferric ions, being the nitrite in the “promoting” role of the reaction. Linear calibration plots are obtained for nitrite concentration ranges 0.3–2.4 ppm or 0.66–6 ppb. The influence of foreign compounds is also established.
Influence of Grain Size, Oxygen Stoichiometry, and Synthesis Conditions on the γ-Fe2O3 Vacancies Ordering and Lattice Parameters
2002
The soft chemistry method has been used to synthesize γ-Fe2O3 nanoparticles: various synthesis temperature were applied to obtain nanometric powders with crystallite size in the 9–14 nm range. Powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometry, surface area measurements, and electron microscopy (TEM, SEM). It is clearly shown that these nanometric powders are very well crystallized as indicated by XRD and IR spectra which present substructural bands attributed to vacancies ordering (P4132). Based on these model materials and in the crystallite size range studied here, cell parameter appears to be not linked to crystallite size. It rat…
Four color-measuring devices compared with a spectrophotometric reference system
2009
Abstract Objectives The objective of this study was to compare the L*C*h° color coordinates of dental color-measuring devices with those of a spectrophotometric reference system. Methods The International Commission on Illumination (CIE) L*C*h° color coordinates of ceramic samples, matching the colors of the VITA Linearguide, were recorded using four color-measuring devices (VITA Easyshade (A), VITA Easyshade compact (B), Degudent Shadepilot (C), X-Rite Shadevision (D)) and a spectrophotometric reference system under standardized test conditions. The intraclass correlation coefficients, regression lines with coefficients of determination, and mean deviations of the dental color-measuring de…
Effects of diazinon exposure on cholinesterase activity in different tissues of European eel (Anguilla anguilla).
1996
Cholinesterase (ChE) activity was measured in brain, plasma, and whole eye of Anguilla anguilla experimentally exposed to a sublethal concentration of 0.042 mg/liter (0.50 of the 96-hr LC50) of the organophosphorous pesticide diazinon. Whole eye was the tissue which revealed higher values of ChE activity (8.17 micromol/min/g) in nonexposed animals. Brain, plasma, and whole eye ChE activity of A. anguilla was inhibited at 6, 24, 48, 72, and 96 hr of diazinon exposure. Pesticide induced significant inhibitory effects on the ChE activity of this species ranging from >70% inhibition in brain tissue to >90% in plasma samples. Brain and plasma presented technical difficulties in their collection.…
Towards a Rapid Screening of Liver Grafts at the Operating Room Using Mid-Infrared Spectroscopy
2020
The estimation of steatosis in a liver graft is mandatory prior to liver transplantation, as the risk of graft failure increases with the level of infiltrated fat. However, the assessment of liver steatosis before transplantation is typically based on a qualitative or semiquantitative characterization by visual inspection and palpation and histological analysis. Thus, there is an unmet need for transplantation surgeons to have access to a diagnostic tool enabling an in situ fast classification of grafts prior to extraction. In this study, we have assessed an attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic method compatible with the requirements of an operatio…
Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components.
1990
. Successful oral litholytic and other non-operative therapies of gallstones require exact determination of the stone components. Since computed tomography (CT) provides highly sensitive measurement of density, we performed a study to evaluate whether CT measurement of stone density allows a prediction of the composition of radiolucent gallstones. Twenty-eight patients presenting with 29 radiolucent gallbladder (n= 17) or common bile duct stones (n=12) were included. Prior to operative or endo-scopic therapy the attenuation values (Hounsfield Units, HU) were assessed in vivo by CT under standardized conditions (Somatom II, 125 KV, 130 mAs). After surgical or endoscopic stone removal the con…
Use of a three-factor interpretive optimisation strategy in the development of an isocratic chromatographic procedure for the screening of diuretics …
2000
Screening of diuretics in urine is feasible through direct injection of the samples into the chromatographic system and isocratic reversed-phase liquid chromatography (RPLC) with micellar-organic mobile phases of sodium dodecyl sulfate (SDS) and 1-propanol. The surfactant coverage of the chromatographic column makes the addition of organic competing amines less necessary than in conventional aqueous-organic RPLC to achieve well-shaped peaks. Also, the range of elution strengths of micellar mobile phases required to elute mixtures of hydrophobic and hydrophilic diuretics is smaller. This allows the isocratic separation of the diuretics within adequate analysis times. An interpretive methodol…
Determination of Neodymium Diphthalocyanine and its Utilization in Qualitative and Quantitative Evaluation of Synthetic Products
1993
Przedstawiono prostą metodę spektrofotometryczną w zakresie VIS, ilościowego oznaczania diftalocyjaniny neodymu, zarówno w surowych produktach reakcji syntezy jak i oczyszczonym materiale. Polega ona na pomiarach absorbancji badanych próbek w roztworze DMF przy czterech różnych długościach fal, tj. 500, 633, 671 i 800 nm. Zawartość diftalocyjaniny oblicza się z krzywej kalibracyjnej, przedstawionej w postaci równania liniowego.