Unique Inline Sample Preparation Technique for the Analysis of Calcium in Milk using Ion Chromatography

Calcium is an essential mineral in the human diet and is essential for strong bones and teeth as well as blood clotting, the transmission of nerve impulses and regulation of the heart’s rhythm. Ninety nine percent of calcium in the human body is stored in blood and teeth with the remaining one percent found in blood and other tissues. One way to get calcium into body is by eating foods that contain good sources of calcium such as diary sources like milk so being able to determine reliably the calcium in such products is of importance to those associated with the diary industry.

Using Dialysis with its novel and patented "stopped flow technique" then the sample preparation can be performed automatically inline reducing the extensive labour requirements historically placed upon the user, expanding the sample throughput, minimising the associated errors and enhancing the lifetime of the separation columns. Today, automated inline sample preparation is a key requisite for many laboratories when considering purchase of analytical instrumentation and Metrohm recognizes this fact having introduced its first such system over 10 years ago, hardly surprising given that their origins in Ion Analysis are themselves over sixty years old. Dialysis is neither filtration, nor extraction, nor digestion and works upon the principle that the analyte ions of interest in the sample matrix diffuse from a sample solution over a membrane into an acceptor solution to achieve a concentration equilibrium. The larger particles (>0.2µm) are transported to waste past the membrane meaning that each membrane has a life of up to one week.

The analysis of calcium in milk can easily be achieved using an 861 Advanced Compact IC with the 838 Advanced IC Dialysis Sample Processor, where the dialysis cell is integrated onto the side of the tower. The running costs of the IC system are minimal with no costly replacement of suppressor membranes or eluent cartridges required – themselves nothing more than a marketing ploy – instead IC from Metrohm offers power and flexibility as an alternative to the analyst. The diluted milk sample was placed on the carousel of the sample processor and then dialysed automatically using a mobile phase of 3mM Nitric Acid against a Metrosep C2 Separation Column with a peak for calcium obtained in less than 12 minutes.

To learn more about the benefits of Dialysis and Inline Sample Preparation from Metrohm, then please telephone or click 'request more info', where our IC Applications Support Team will be delighted to provide further application information.