In recent years, society has become aware of the dangers of excessive salt intake, which is linked to high blood pressure and cardiovascular disease. Initiatives of the food and health organizations were taken, making sodium determination, sodium content declaration and product labeling mandatory. With the new Titration Excellence family it is now possible to directly measure the sodium content in food based on the dedicated multiple standard addition technique – simple, accurately and fully automated.
Multiple standard addition technique
The standard addition technique is a quantitative analysis whereby a standard ion solution of known concentration is added to a known sample volume in multiple steps. The measurement is performed using a sodium glass ion-selective electrode as the measuring element and a silver/silver chloride system as a reference electrode. Sensor calibration values are obtained during the measurement itself - no further calibration is necessary!
This method was first introduced with the stand-alone sodium analyzer from METTLER TOLEDO. The new Titration Excellence line now also supports the multiple standard addition technique, allowing direct sodium determination to be fully automated. Together with the InMotion™ Autosampler, a whole series of samples can be automatically analyzed for sodium content. This not only speeds up the workflow, but also protects operators from potentially harmful chemicals.
Great application versatility
Using the multiple standard addition technique, operators can determine the sodium content of most food products directly without extensive sample preparation. Liquid and solid homogeneous samples can be added directly to the analysis beaker. Deionized water and ionic strength adjustment buffer can be added automatically using an additional dosing unit. For inhomogeneous samples it is recommended to prepare a dilution solution to improve repeatability of the results.
The multiple additions reduce any matrix effects in the sample. As a result, the sodium content of a wide variety of samples can be successfully determined. Testing revealed that the integrated, stable algorithm efficiently delivers accurate and repeatable results:
The ideal solution
The multiple standard addition technique provides comparable results to traditional methods used for direct sodium analysis, such as atomic absorption spectroscopy, ion chromatography and inductively coupled plasma spectroscopy. But it does not require their complex and elaborative sample preparation, the need for in-depth user knowledge or expensive equipment or chemicals.
The simplicity and high accuracy of this technique allows food companies to perform their own analyses rather than having to rely on external research labs. Considering the increased public awareness of the health implications connected to excess sodium intake and the increasing pressure on food manufacturers to monitor and declare the sodium content, this dedicated tool has arrived just at the right time.