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Determinação potenciométrica em fluxo de cloreto de cetilpiridinio em desinfectantes bucais IPB - Escola Superior Agrária
Baptista, Paula; Araújo, Alberto N.; Montenegro, Maria da Conceição B. S. M..
The work describes a new procedure for cetylpyridinium chloride determination in oral disinfectants, based on a flow-injection system with potentiometric detection. The determination was based on the measurement of picrate concentration decrease as result of ion-pair reaction with the analyte present in the injected sample. In the optimised set-up the sample injection volume was kept at 400 µL and merged downstream with the reagent solution containing 1,0 x10-5 mol/L of picrate adjusted to pH 5.0 with citrate/citric acid buffer. The flow rate was fixed at 8 mL/min and the reactor length at 40 cm. The proposed procedure enables the determination of cetylpyridinium in the analytical range of 5,0x10-6 – 7,5x10-5 mol/L at a sampling rate of 60/h. The results...
Tipo: Article Palavras-chave: Potentiometry; Oral disinfectants; FIA; Ion-selective electrodes; Cationic surfactants; Spectrophotometric determination; Pharmaceutical preparations; Capillary electrophoresis; Pair extraction; Construction; Titrations; Sensor.
Ano: 2003 URL: http://hdl.handle.net/10198/938
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DNA-lipid systems: A physical chemistry study BJMBR
Dias,R.; Antunes,F.; Miguel,M.; Lindman,S.; Lindman,B..
It is well known that the interaction of polyelectrolytes with oppositely charged surfactants leads to an associative phase separation; however, the phase behavior of DNA and oppositely charged surfactants is more strongly associative than observed in other systems. A precipitate is formed with very low amounts of surfactant and DNA. DNA compaction is a general phenomenon in the presence of multivalent ions and positively charged surfaces; because of the high charge density there are strong attractive ion correlation effects. Techniques like phase diagram determinations, fluorescence microscopy, and ellipsometry were used to study these systems. The interaction between DNA and catanionic mixtures (i.e., mixtures of cationic and anionic surfactants) was...
Tipo: Info:eu-repo/semantics/article Palavras-chave: DNA; Cationic surfactants; Catanionic mixtures; Chitosan; Phase behavior; Polyelectrolyte-oppositely charged surfactant systems.
Ano: 2002 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002000500002
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