Análise potenciométrica de redissolução com ultramicroeletrodos: fundamentos e aplicações na determinação de metais traços. Quím. Nova [online]. 09/02/ la química analítica es la parte de la química que estudia, diseña, desarrolla, optimiza y aplica métodos y técnicas que se materializan en. fundamentos fisioquímicos grado farmacia us métodos químicos: son todos aquellos que se basan casi exclusivamente en reacciones químicas en los que la.
|Published (Last):||13 February 2017|
|PDF File Size:||17.96 Mb|
|ePub File Size:||2.8 Mb|
|Price:||Free* [*Free Regsitration Required]|
No processo de refino, por ex. Different methods of the selectivity determination can be found in the literature. Negative values indicate a preference for the target ion ra to the interfering ion.
According to the nature of the binding sites, the membranes can be fundamenttos as: Typically, the electrode calibration curve exhibits linear response range between M and M. Rio de Janeiro,vol.
For crude and degummed oils, the titration end point is difficult to be observed due to the high level of pigments, resulting in dark solutions.
However, it should be pointed out that a single time constant does not describe the form of the electrode response function. Food Protection53 This membrane can be prepared as: Fundamehtos this case and others, such as self-life studies, in which sample quantities are limited, potentiometric titration potendiometria be a very good alternative.
For fnudamentos reason the potential of sucha membrane is governed mainly by the activity of the primary target ion and also by the activity of othersecondary interfering ions. Typical calibration curve of a potentiometric sensor determined in this way is shown in figure 2. Nova17 A useful slope can be regarded as [mV per decade] [mV per decade] for double charged ion respectively.
Rio de Janeiro,cap. According the IUPAC dq the detection limit is defined by the cross-sectionof the two extrapolated linear parts od the ion-selective calibration curve. All the contents of this journal, except where otherwise noted, is fubdamentos under a Creative Commons Attribution License. The selectivity is one of the most important characteristics of an electrode, as it oftendetermines whether a reliable measurement in the sample is possible or not.
In practice the potential difference i. The selectivity coefficient Kxy has been introducedin the Nikolski-Eisenman equation.
In practice, detection limit on the order of M is measured for most of ion-selective electrodes. Potentiometric titration applied to free fatty acid determination of edible oils and fats. If ions fundametos penetrate the boundary betweentwo phases, then an electrochemical equilibrium will be reached, in which different potentials in the two phases are formed.
Funsamentos 10 for WindowsMinitab: The observed detection limit is often governedby the presence of other interfering ions or impurities.
It establishes the preference with which the sensor responds to the analyte in the presence of various interfering ions from the sample. However, in certain applications the value of the electrode slope is not criticaland worse value does not exclude its usefulness.
[Potencio & Conduto] Aula – Métodos Eletroquímicos e Titulação Potenciométrica (Guts)
Free fatty acids are a measure of evaluating fats fundamrntos oils, submitted to abusive conditions, besides being a quality characteristic potencioemtria edible vegetable oils. Positive values of log Kxy indicate the preference of an electrode for theinterfering ion. The measured signal is the sum of different potentials generated at all solid-solid, solid-liquid and liquid-liquid interfaces. Alterando as quantidades de amostra utilizadas. However, a membrane truly selective for a single typeof an ion and completely non-selective for other ions does not exist.
This definition can be extended to consider the drift of the system. New York,cap.