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101.
Silvia Ružičková Jolana Bajuszová Ladislav Koller Mikuláš Matherny Karol Flórián 《Mikrochimica acta》2006,156(1-2):115-120
The evaporation as a part of the spectrochemical excitation process is a complicated procedure during which different thermo-chemical
reactions connected mainly to the formation of carbides are overshot. This one is accelerated namely at the 4000 K on the
top of the carrier electrode. The carbide creation markedly affects the evaporation process of single elements of the given
matrix and modifies this process. In spite of this it is evident that the intensity of the DC arc has a significant impact
on the evaporation of all elements.
The evaporation capability of two optical methods, the classical non-controlled direct current (DC) arc spectrography and
the PC controlled DC arc optical emission spectrometry, have been compared for the determination of some environmental important
elements (Al, Cr, Ni, and V). The experiments were carried out using grating spectrograph PGS-2 and simultaneous multi-channel
LECO 750 spectrometer which is connected to a separated evaporation cell and adjusted to the Marinković plasma source. Standardized
evaporation curves were designed and the half-time (t50%) values and the total (t100%) evaporation time values were calculated. The basic statistical evaluation was done and the main figures of the merit were
calculated. 相似文献
102.
The elements Mn and V were determined by INAA in about 5 mg and 100 mg aliquots of NIST SRM 1648 to elucidate discrepancies between our previous results for the 0.5 mg to 15 mg aliquots and the NIST certified and/or information values. Simultaneously, other NIST SRMs 1633a, 2704, and BCR CRMs 038, 101 and 143 were also analyzed. Special attention was given to evaluating and minimizing uncertainties of all steps of analysis. Our results compared very well with the respective certified and/or information values (if available) of all SRMs and CRMs studied, except for NIST SRM 1648. For this SRM we have found significantly lower results than the NIST values which suggests that the NIST values are positively biased by about 10%. A new value for V in BCR CRM 143 was also obtained. 相似文献
103.
Butorphanol tartrate is a synthetic opioid agonist-antagonist used as analgesic, possessing three chiral centres in the basic part of the molecule. Its chiral purity is routinely controlled only by optical rotation. A new capillary zone electrophoresis method, capable to separate the enantiomers of butorphanol and intermediate of its synthesis, cycloamine, was developed. Different electrolyte composition (type and concentration of carrier ion, pH, and organic solvent addition), and type and concentration of several chiral selectors (natural and modified cyclodextrins) were tested. Using the optimized conditions (acidic electrolyte with the addition of highly sulphated gamma-cyclodextrin) as low as 0.05% of undesirable enantiomers can be detected. Selected method characteristics, i.e., linearity (0-50 mg/l), precision (2.5% at 20 mg/l), and accuracy (101 +/- 2% at 20 mg/l) were evaluated. The optimized method was applied for the analysis of real batches of butorphanol and cycloamine. It was found that butorphanol tartrate manufactured by IVAX Pharmaceuticals contains less than 0.05% of undesirable enantiomer. 相似文献
104.
Andrea?TuroňováEmail author Miriam?Gálová Magdaléna??upicová Ladislav?Lux 《Journal of Solid State Electrochemistry》2003,7(10):689-693
The composition of a two-component Ni-Cu coating and the efficiency of its electrochemical deposition on Fe powder was studied
by constant current electrolysis. A fluidized bed arrangement was applied. The variable parameters were: the particle size
fraction, the density of the suspension of the Fe powder in the plating bath, and the intensity of the stirring of the fluidized
bed. Both the Cu and Ni contents in the deposit decrease with increase in the particle size, and with decrease in the suspension
density. Thus, the surface area available for the electrochemical process proved to be of high importance. Another important
factor is the quality of the contacts of the powder particles with the current carrying compact electrode during which the
deposition of Ni is preferred. This influence is manifested in a decrease of the Ni-Cu ratio in the deposit with an increase
in the particle size and rotation speed and, consequently, with a decrease in the suspension density. The current efficiency
values on the powder for optimum conditions reached 80%. 相似文献
105.
Pyrolysis-capillary gas chromatography (Py-cGC) represents important method to identify the analytes in the mixture after thermal degradation. This combines high effective analyte separation on-line coupled with thermal degradation process that depends on analyte structure. System of retention indices has been used for identification of the analytes after on-line pyrolysis and chromatographic separation. The pyrolysate composition has been studied during thermal degradation of polymethylmethacrylate (PMMA) at different pyrolysis temperatures and chromatographic column conditions. Homologues series of n-alkanes have been used for calculation of pyrolysate Kováts retention indices (I) and compared with mass spectrometric (MS) data of pyrolysate model mixture. To identify PMMA thermal degradation products the high density polyethylene (HDPE) as additive standard producing triplets of the olefin homologous series during co-pyrolysis has been used. These homologous series enable to calculate programmed temperature retention indices (ITPGC) to identify the analytes present in the pyrolysate. Calculated I values were compared with published I values databases to identify analytes yielded at different pyrolysis temperatures. 相似文献
106.
Kalenda Petr Koudelka Ladislav Mošner Petr Beneš Ludvík Černošek Zdeněk 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2303-2310
Journal of Thermal Analysis and Calorimetry - The thermal behavior and crystallization of barium molybdate-phosphate glasses were studied in two compositional series, namely A:... 相似文献
107.
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110.
Zuzana Bujdošová Katarína Györyová Daniela Hudecová Jana Kovářová Ladislav Halás 《Chemical Papers》2010,64(5):584-591
New zinc(II) 4-chloro- and 5-chlorosalicylate complex compounds of the general formula ((4- or 5-Cl)C6H3(2-OH)COO)2Zn · L
n
(where L = methyl 3-pyridylcarbamate, phenazone; n = 2, 4) were prepared and characterized by elemental analysis, thermal analysis (TG/DTG, DTA), and IR spectroscopy. During
thermal decomposition, mpc, phen, chlorosalicylic acid, chlorophenol, carbon dioxide, and carbon monoxide were released. Volatile
products of the thermal decomposition were confirmed by mass spectrometry. The final solid product of the thermal decomposition
up to 700°C was zinc oxide or metallic zinc. Antimicrobial activity of the compounds prepared was tested against various strains
of bacteria, yeasts and filamentous fungi. The highest antimicrobial effect was determined against the G+ bacteria S. aureus. 相似文献