Strontium is a microcomponent of waters. A lot is known regarding the negative effects
of elevated strontium concentrations on human health. Being close to calcium by its chemical
properties strontium sharply differs in its biological action. Excess levels of this element in water
cause the substitution by strontium of calcium in bones, liver and brain. This pathology is a
reflection of the competitive relations of strontium and calcium in their distribution in the body.
Determination of microcomponents on the background of high concentrations of major
components of water is always associated with the possibility to get a wrong result due to the
occurrence of spectral and matrix effects. We studied the effect of sodium ions on the results of
determination of strontium concentrations by emission flame photometry. This is due to the fact
that sodium is a macrocomponent of water and its content in drinking water in Moldova is
limited to 200 mg/l. At the same time, our experience shows that sodium concentration in the
waters of Moldova is highly variable and can range from small concentrations to concentrations
far exceeding the maximum permissible value. In the present study we evaluated the use of
flame emission photometry method for determining the concentration of strontium ions in water
in the presence of various concentrations of sodium ions and a comparison with the method of
atomic absorption spectrometry. The research work was carried out on model solutions and the
natural mineral water from Soroca
It was shown that the presence of high sodium content in water leads to an overestimation
of results in determination of strontium by flame photometry. Thus, the concentration of
strontium (1.0 mg/L) increases 1.33 times if sodium ion concentration is 230 mg/l, 1.66 times
when concentration of sodium ions is 575 mg/L and 2.33 fold at a concentration of sodium ions
of 1150 mg/l.
A linear dependence of the background radiation on the sodium concentration was
established for the method of emission flame photometry at a wavelength of 460.7 nm (spectral
emission line of strontium). The greatest impact of high concentrations of sodium on the result of
determining the concentration of strontium ions is at low levels of strontium.
It was shown that taking into consideration the background radiation of sodium ions
allows to obtain reliable results.
During this study was revealed the overwhelming influence of nitric acid to
determination of strontium concentration by flame photometry.
In the case of using the method of atomic absorption spectroscopy in the determination of
strontium in different types of waters there have been identified no interferences of sodium ions
or nitric acid.
Metrological characteristics of both methods were assessed.