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21859 Titrotherm from Metrohm for the thermometric titrationAB-298Automated sodium determination in various foodsConsumers and regulatory agencies are pushing harder thanever for the accurate analysis of sodium in food products. Directmeasurement methods like atomic absorption spectroscopy (AAS)or inductively coupled plasma spectroscopy (ICP) are very costandtime-consuming for testing labs. For this reason, many foodcompanies have indirectly analyzed sodium by using the results ofchloride analysis. The amount of sodium is then typically calculatedby assuming a 1:1 molar ration of chloride ions to sodium ions inthe food. This is not necessarily the case especially when commonsodium-containing food ingredients, such as sodium benzoate andmonosodium glutamate, or chloride-containing ingredients such aspotassium chloride, are present in the food matrix.To determine the amount of sodium in foodstuffs, no cumbersomemanual sample preparation steps are necessary. The food is firsthomogenized fully automatically by a high-frequency homogenizerPolytron 1300D - (which can be mounted on a USB Sample Processor).Then, ammonium hydrogen difluoride is added to the sample,followed by a thermometric titration with a standardized aluminumsolution which contains a stoichiometric excess of potassium ions. Inthis exothermic reaction, insoluble NaK 2AlF 6 is obtained:Al 3+ + Na + + 2K + + 6F –NaK 2AlF 6