Section: Methodology and research methods. Models and forecasts
The paper presents a flow-injection technique for ionometric fluorine detection in biological objects. The possibilities of automatic potentiometric titrator “Titrion” application, which allows carrying out controlled dosing of the solution and registering the electromotive force of the electrode system to perform flow ionometric measurements in combination with a specially designed measuring cell, are described. The cell consists of a single plastic housing containing an injector for sample injection with a micro syringe, a mixing chamber, and chambers for the working electrode and reference electrode. The optimum conditions for measurements were selected: the rate of solution passage through the cell, the parameters of mixing the sample with buffer solution, the most rational way of plotting the calibration graph was found. The method of standard fluorapatite composition was successfully tested, as well as samples of kidney stones and tooth enamel from humans and mollusks (Viviparus viviparus L.) shells, transferred into solution by treatment with hydrochloric acid. The developed technique allows carrying out fluorine express determination in biological objects using a small amount of the test substance (10–20 mg) with an absolute detection limit of 10 ng in 1–25 μL of the analyzed solution. The range of fluoride ion concentration detection was 30–500 ng in the analyzed sample. The relative measurement error for the range of measured concentrations does not exceed ±10 % rel. The proposed approach to the analysis is promising for the development of methods for iodide-, nitrate-, chloride- and other anions micro-detection in biological samples and environmental objects.
ISSN 1995-4301
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