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3.
Anal Sci ; 29(7): 753-5, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23842420

RESUMO

A definitive method is described for the indirect assay of several tens of milligrams of urea by coulometric titration. Urea was decomposed in concentrated sulfuric acid using a Kjeldahl flask. Subsequently, the formed ammonium ion was titrated with electrogenerated hypobromite ion in a sodium bromide-sodium tetraborate medium of pH 8.6, with amperometric end-point detection. Parameters affecting the pretreatment procedure were evaluated. The optimized conditions included the heating of 2 g of urea at around 300°C for 2 h with 10 cm(3) of sulfuric acid. Under the proposed conditions, the assay value with expanded uncertainty (k = 2), 99.870 ± 0.026%, agreed well with the certified value of NIST SRM 912a urea, 99.9 ± 0.1%.


Assuntos
Bromatos/química , Técnicas Eletroquímicas , Ureia/análise
4.
Artigo em Inglês | MEDLINE | ID: mdl-21242103

RESUMO

We developed a detection technology for vapor forms of chemical warfare agents (CWAs) with an element analysis system using an electron cyclotron resonance ion source. After the vapor sample was introduced directly into the ion source, the molecular material was decomposed into elements using electron cyclotron resonance plasma and ionized. The following CWAs and stimulants were examined: diisopropyl fluorophosphonate (DFP), 2-chloroethylethylsulfide (2CEES), cyanogen chloride (CNCl), and hydrogen cyanide (HCN). The type of chemical warfare agents, specifically, whether it was a nerve agent, blister agent, blood agent, or choking agent, could be determined by measuring the quantities of the monatomic ions or CN(+) using mass spectrometry. It was possible to detect gaseous CWAs that could not be detected by a conventional mass spectrometer. The distribution of electron temperature in the plasma could be closely controlled by adjusting the input power of the microwaves used to generate the electron cyclotron resonance plasma, and the target compounds could be detected as molecular ions or fragment ions, enabling identification of the target agents.


Assuntos
Substâncias para a Guerra Química/análise , Ciclotrons/instrumentação , Íons/química , Espectrometria de Massas/instrumentação , Espectrometria de Massas/métodos , Gases/análise , Humanos , Micro-Ondas
5.
Talanta ; 73(2): 346-51, 2007 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-19073038

RESUMO

In this paper, we determine the effective purity of potassium iodate as a redox standard with a certified value linked to the international system of units (SI units). Concentration measurement of sodium thiosulfate solution was performed by precise coulometric titration with electrogenerated iodine, and an assay of potassium iodate was carried out by gravimetric titration based on the reductometric factor of sodium thiosulfate assigned by coulometry. The accuracy of the coulometric titration method was evaluated by examining the current efficiency of iodine electrogeneration, stability of sodium thiosulfate solutions and dependence on the amount of sodium thiosulfate solution used. The measurement procedure for gravimetric titration of potassium iodate with sodium thiosulfate was validated based on determination of a reference material of known purity (potassium dichromate determined by coulometry with electrogenerated ferrous ions) using the same gravimetric method. Solutions of 0.2 and 0.5mol/L sodium thiosulfate were stable over 17 days without stabilizer. Investigation of the dependency of titration results on the amount of sodium thiosulfate solution used showed no significant effects, no evidence of diffusion of the sample, and no effect of contamination appearing during the experiment. Precise coulometric titration of sodium thiosulfate achieved a relative standard deviation of less than 0.005% under repeating conditions (six measurements). For gravimetric titration, the results obtained for the effective purity of potassium dichromate were sufficiently close to its certified value to allow confirmation of the validity of the gravimetric titration was confirmed. The relative standard deviation of gravimetric titration for potassium iodate was less than 0.011% (nine measurements), and a redox standard with a certified value linked to SI units was developed.

6.
Anal Sci ; 22(8): 1121-4, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16896254

RESUMO

The precipitation titration of sodium chloride with electrogenerated silver ion was studied. The production of a precipitate of silver chloride had a significant effect on the titration results because the precipitate involved unreacted chloride or unreacted silver ion. The accuracy of the method was investigated by changing the introduction time of a sodium chloride solution to the coulometric cell during the process of electrolysis, and examining the dependency on the sample size. The accuracy of the measurement of the precipitation titration is discussed.


Assuntos
Técnicas de Química Analítica/métodos , Colorimetria/instrumentação , Colorimetria/métodos , Compostos de Prata/química , Cloreto de Sódio/química , Automação , Precipitação Química , Eletrólise , Desenho de Equipamento , Íons , Reprodutibilidade dos Testes , Projetos de Pesquisa , Titulometria/métodos
7.
Anal Sci ; 22(3): 461-3, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16733324

RESUMO

The drying conditions for primary standards of volumetric analysis have a significant effect on the titration results due to changes in the purity, stability and homogeneity. Amidosulfuric acid, a strong acid used as a reference material for volumetric analysis in Japan, was dried in a vacuum desiccator or heated at different temperatures, and then measured by Karl-Fischer titration, thermogravimetry/mass spectroscopy (TG-MS), ion chromatography and coulometric titration. The optimum drying conditions were at 50 degrees C for 24 h with crushing.

9.
Ann Pharmacother ; 39(3): 563-6, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15701776

RESUMO

OBJECTIVE: To report 2 cases of patients with Down syndrome and severe cognitive impairment who gained dramatic improvements in quality of life (QOL) upon donepezil treatment. CASE SUMMARIES: Case 1. A 38-year-old woman with Down syndrome, diagnosed with secondary progressive dementia when her mental state had deteriorated rapidly after graduation from junior high school, started donepezil treatment. The loading dose was 3 mg/day and was increased to 5 mg/day for maintenance. One month after the dose was increased, adverse effects such as soft stool and urinary incontinence appeared. These adverse effects disappeared when the dose was decreased again to 3 mg/day. Her QOL improved dramatically with this minimal dose. She recovered verbal and written communication skills that she had lost for the past 21 years. Case 2. A 22-year-old man with Down syndrome, who had been diagnosed as having severe mental retardation, was put on donepezil therapy. Both loading and maintenance doses were 3 mg/day. His QOL had also dramatically improved, with some recovery in verbal communication. Transient agitation/violence and transient muscle weakness appeared during the first few months of treatment. DISCUSSION: Patients with Down syndrome may be more sensitive to donepezil therapy than others and may benefit from this medicine, although they may also have adverse effects more frequently. CONCLUSIONS: Donepezil may be a useful medicine for some patients with Down syndrome with severe cognitive impairment or mental retardation if the adverse effects are manageable.


Assuntos
Inibidores da Colinesterase/uso terapêutico , Transtornos Cognitivos/tratamento farmacológico , Síndrome de Down/complicações , Indanos/uso terapêutico , Piperidinas/uso terapêutico , Adulto , Inibidores da Colinesterase/efeitos adversos , Transtornos Cognitivos/etiologia , Demência/tratamento farmacológico , Demência/etiologia , Donepezila , Síndrome de Down/psicologia , Feminino , Humanos , Indanos/efeitos adversos , Deficiência Intelectual/tratamento farmacológico , Masculino , Piperidinas/efeitos adversos , Qualidade de Vida
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