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AssigneeApplikon Dependable Instruments B.V.
InventorRobert Hoogendijk
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The invention relates to a method of determining an ion concentration with the aid of an ion-selective electrode, in which method a known quantity by volume of a sample is taken, a buffer is added and the initial potential of the electrode pair is measured, a known volume having an accurately known ion concentration is added and the potential obtained is measured, the standard solution being added stepwise, and the initial potential of the electrode pair and the slope of the relationship between potential and logarithm of the concentration is calculated for each of the quantities added from the data obtained, a small quantity of the solution to be determined is added, the potential difference is measured and the latter is compared with the required sudden change in potential, after which a sample is again taken and a quantity of the solution to be determined is added which is expected to bring the sudden change in potential into the required region, the potential is then read off and the required concentration is calculated. A description is furthermore given of an apparatus which is suitable for performing said method.
Method of determining, with the aid of an ion-selective electrode ion selective electrode the concentration of a substance to be determined, which comprises taking a known volume of a sample, a buffer is added to a sample solution in order to produce a medium in which a potential of the ion selective electrode is directly related to the concentration of a respective ion and, after a set reaction time, an initial potential of the electrode pair including an ion-selective electrode and reference electrode is measured, then a known volume of a solution having an accurately known concentration of the substance to be determined which is a standard solution is added and a change in potential produced is measured, and the concentration of the substance to be determined is calculated therefrom, including the steps of providing that the addition of the standard solution to a reaction mixture is carried out in steps, the first addition being a small one which brings about a change in potential which indicates what the concentration of a substance to be determined is approximately, then further additions are made on the basis of the change in potential produced until a final change in potential is such that it corresponds to an increase in concentration of 1.5 to 10 times the concentration of the substance to be determined which was present in the sample.
Dependencies are inferred from the claim text.