981 resultados para HR-CC FAAS


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A simple method to determine Cu, Fe, Mn and Zn in single aliquots of medicinal plants by HR-CS FAAS is proposed. The main lines for Cu, Mn and Zn, and the alternate line measured at the wing of the main line for Fe at 248.327 nm allowed calibration within the 0.025 - 2.0 mg L-1 Cu, 1.0 - 20.0 mg L-1 Fe, 0.05 - 2.0 mg L-1 Mn, 0.025 - 0.75 mg L-1 Zn ranges. Nineteen medicinal plants and two certified plant reference materials were analyzed. Results were in agreement at a 95% confidence level (paired t-test) with reference values. Limits of detection were 0.12 μg L-1 Cu, 330 μg L-1 Fe, 1.42 μg L-1 Mn and 8.12 μg L-1 Zn. Relative standard deviations (n=12) were ≤ 3% for all analytes. Recoveries in the 89 - 105% (Cu), 95 - 108% (Fe), 94 - 107% (Mn), and 93 - 110% (Zn) ranges were obtained.

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Microwave-assisted acid decomposition, direct dilution in kerosene, and oil-in-water emulsion were evaluated as lubricating oil pretreatment procedures for Cu, Cr, Fe, Ni, Pb, Sb, and Zn determination by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). For wet digestion, results were compared with those obtained by Flame Atomic Absorption Spectrometry (FAAS). The ultrasound probe used in emulsions sonication contaminated samples with Cr, although better results have been observed for the other six elements in this condition. In general, recovery percentages ranging from 81-106%(Cu), 80-107%(Cr), 85-114%(Fe), 82-116%(Ni), 86-117%(Pb), 85-115%(Sb), and 81-114%(Zn) were obtained. The HR-CS FAAS showed to be faster and more sensitive than FAAS.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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This work describes a method to determine Cu at wide range concentrations in a single run without need of further dilutions employing high-resolution continuum source flame atomic absorption spectrometry. Different atomic lines for Cu at 324. 754 nm, 327. 396 nm, 222. 570 nm, 249. 215 nm and 224. 426 nm were evaluated and main figures of merit established. Absorbance measurements at 324. 754 nm, 249. 215 nm and 224. 426 nm allows the determination of Cu in the 0. 07-5. 0 mg L -1, 5. 0-100 mg L -1 and 100-800 mg L -1 concentration intervals respectively with linear correlation coefficients better than 0. 998. Limits of detection were 21 μg L -1, 310 μg L -1 and 1400 μg L -1 for 324. 754 nm, 249. 215 nm and 224. 426 nm, respectively and relative standard deviations (n = 12) were ≤ 2. 7%. The proposed method was applied to water samples spiked with Cu and the results were in agreement at a 95% of confidence level (paired t-test) with those obtained by line-source flame atomic absorption spectrometry.

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Solid-state M-L compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG-DSC coupled to FTIR, elemental analysis and high-resolution continuum source flame atomic absorption spectrometry technique (HR-CS FAAS) were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the composition, dehydration, thermal stability and thermal decomposition. © 2013 Akadémiai Kiadó, Budapest, Hungary.

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The wavelength-integrated absorbance (WIA) and summation of absorbance (∑ lines) of different lines were evaluated to enhance sensitivity and determine B, P and S in medicinal plants by HR-CS FAAS. The lowest LOD for B (0.5mgL-1) and P (13.7mgL-1) was obtained by integration of lines 249.773nm (3pixels) and 247.620nm (5pixels), respectively. The ∑ lines for CS at 257.595nm and 257.958nm furnished LOD=30.5mgL-1, ca. 10% lower than the LOD obtained for the WIA using 257.595nm and 5pixels. Data showed the advantage of WIA over ∑ lines to improve sensitivity for all analytes. Under optimized conditions, calibration curves in the 1.0-100mgL-1 B and 50.0-2000mgL-1 P, S ranges were consistently obtained. Results obtained with the HR-CS FAAS method were in agreement at 98% and 95% confidence level with certified values for B and P, respectively. And results for S were in accordance to non-certified values. Concentrations of B, P, and S in 12 medicinal plants analyzed by the proposed method varied within the 19.4-34.5mgkg-1 B, 719-3910mgkg-1 P and 1469-7653mgkg-1 S ranges. © 2012 Elsevier B.V.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)