284
D. Toczek et al.
9.3.1 Flame Photometry
The flame atomic emission spectrometry (FAES) was used by us to measure the complexing ability of tested compound. The flame photometry constitutes the relatively
sensitive method which allows the determination of studied element concentrations
in the range of 0.1–1000 ppm with a relative small error of 1–3 %. This approach
was used for the determination of the calcium concentration in the water solution
over solid calcium oxalate i.e. the shift of the solid–liquid interphase equilibrium in
and without the presence of synthetic or natural complexing agent [45–47].
9.3.2 Conductometric Titration
The conductometric titration is based on the observation of changes in the conductivity of the analyzed solution during the addition of the titrating reagent—(sodium
oxalate in this case) to the solution of calcium chloride and the complexing agent.
The formation of the complex results in a decreasing of conductivity. Since some
of calcium ions are complexed and they are not participating in the conductance. In
this reaction, during the addition of Na
+
and C 2 O 4
2 −
, the insoluble calcium oxalate
is formed. The conductivity of such solution decreases until it reaches the end point
(EP) of titration, which corresponds to the moment when the total amount of Ca
2 +
ions in the solution is bonded. The conductivity of the solution at this point is minimal. Further addition of sodium oxalate result in increase of conductivity because
of the excess of Na
+
and C 2 O 4
2 −
ions. If addition the analyzed compound causing
that EP is reached sooner than in standard curve, that mean the compound possess
complexing ability to calcium ions. The end point of the titration is thus a measure
of the degree calcium ions complexing. The greater difference with respect to the
calibration curve, the better properties of the inhibition of calcium oxalate formation. When EP values of the standard curve and the curve with analyte are similar,
it is considered that the compound does not have the properties of inhibiting of the
formation of calcium oxalate. This method was applied to measure the properties of
studied compounds [48, 49].
9.4 Results and Discussion
The flame photometry and conductometric titration methods were used to evaluate
the complexing property of pure synthetized compounds as well as plant extracts
containing polyphenol glycosides [45]. Several glycosides of hydroxyanthraquinones were prepared. The synthesis was conducted according to a four-step method
consisting acetylation of sugar compounds, their bromination, coupling with hydroxyanthraquinone, and finally the removal of acetyl groups. Properties of pure
D. Toczek et al.
9.3.1 Flame Photometry
The flame atomic emission spectrometry (FAES) was used by us to measure the complexing ability of tested compound. The flame photometry constitutes the relatively
sensitive method which allows the determination of studied element concentrations
in the range of 0.1–1000 ppm with a relative small error of 1–3 %. This approach
was used for the determination of the calcium concentration in the water solution
over solid calcium oxalate i.e. the shift of the solid–liquid interphase equilibrium in
and without the presence of synthetic or natural complexing agent [45–47].
9.3.2 Conductometric Titration
The conductometric titration is based on the observation of changes in the conductivity of the analyzed solution during the addition of the titrating reagent—(sodium
oxalate in this case) to the solution of calcium chloride and the complexing agent.
The formation of the complex results in a decreasing of conductivity. Since some
of calcium ions are complexed and they are not participating in the conductance. In
this reaction, during the addition of Na
+
and C 2 O 4
2 −
, the insoluble calcium oxalate
is formed. The conductivity of such solution decreases until it reaches the end point
(EP) of titration, which corresponds to the moment when the total amount of Ca
2 +
ions in the solution is bonded. The conductivity of the solution at this point is minimal. Further addition of sodium oxalate result in increase of conductivity because
of the excess of Na
+
and C 2 O 4
2 −
ions. If addition the analyzed compound causing
that EP is reached sooner than in standard curve, that mean the compound possess
complexing ability to calcium ions. The end point of the titration is thus a measure
of the degree calcium ions complexing. The greater difference with respect to the
calibration curve, the better properties of the inhibition of calcium oxalate formation. When EP values of the standard curve and the curve with analyte are similar,
it is considered that the compound does not have the properties of inhibiting of the
formation of calcium oxalate. This method was applied to measure the properties of
studied compounds [48, 49].
9.4 Results and Discussion
The flame photometry and conductometric titration methods were used to evaluate
the complexing property of pure synthetized compounds as well as plant extracts
containing polyphenol glycosides [45]. Several glycosides of hydroxyanthraquinones were prepared. The synthesis was conducted according to a four-step method
consisting acetylation of sugar compounds, their bromination, coupling with hydroxyanthraquinone, and finally the removal of acetyl groups. Properties of pure