Determination of mineral contents in nonalcoholic beverages Application Note · Flame AAS

Introduction

The testing of beverages such as mineral water, fruit juice and soft drinks for element contents is a common application in industrial quality control laboratories of beverage producers. Of particular interest are elements such as Ca, Fe, K, Mg and Na, as they are also shown on beverage packaging.

The concentration of these minerals typically ranges from low mg/L to a few g/L depending on element and beverage. Apple juice for example contains usually about 1g/L of potassium and 5 mg/L of iron as essential nutrients. In mineral waters potassium levels are expected to be below 5 mg/L though, and for iron only trace levels are expected to avoid coloring of mineral waters. The working range of the flame AAS technique matches the concentration for the elements of interest; hence, most beverage samples are analyzed by flame AAS directly after sample dilution.

The note describes a simple and fast flame AAS routine for quality control of beverage samples applicable for the novAA 800, ZEEnit 700P and contrAA 800 series from Analytik Jena. To improve the ease of use and to increase productivity, the autosampler AS-FD was used for (i) the preparation of calibration standards from a stock solution and for (ii) automatic dilution of different beverage samples (up to a factor of 1:500) to bring the element concentrations into the typical calibration range of the flame AAS technique. Further flame accessories like the SFS 6.0, the switching valve technology for AAS, improve the analytical precision in daily routine work.

Especially with the High Resolution Continuum Source AAS contrAA 800 all analytes can be easily quantified within one method. Due to the generally available spectral information next to the element line, the side pixel evaluation enables the measurement of high element concentration.