Direct Measurement of Minerals (Zn, Mn, Fe, Cu)

Flame atomic absorption spectrophotometers are capable of the direct measurement of samples with a complex matrix and also feature easy operability and maintainability. Although samples normally require digestion by heating prior to measurement, there are cases where samples in liquid form, such as beverages, can be measured directly.

This article introduces an example of the direct measurement of minerals, iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn), that are included in a commercially available wine using a flame atomic absorption spectrophotometer.

Measurement Samples and Method

Red and white wines which were sold commercially were chosen as samples to be measured without pretreatment. Initially, wine samples were measured with a standard added at constant volumes, before spike-and-recovery tests were carried out. In order to increase the stability of the measurement, the levels of Fe were also calculated for 40 samples of the same red wine.

Instrument Configuration and Measurement Conditions

Measurements were carried out using the AA-7000 atomic absorption spectrophotometer. The key features of the measurement environment are noted in Table 1. In the interests of matrix-matching, ethanol was added to the standard as a reagent to attain a 10 v / v% solution.

Measurement Results

The calibration curves of each element are displayed in Figures 1 to 4. The typical concentration (the concentration for 0.0043 absorbance units), determined using the measurements of the standards, can be seen in Table 2, alongside the detection limit (3σ) for each element.

The measurement findings of the wines and the recovery rates are listed in Table 3. Figure 5 details the findings from measuring the levels of Fe in the red wine in over 40 samples. It can be seen that the average concentration across these samples is 1.74 mg per L, with a relative standard deviation (%RSD) of 1.2%.

Conclusion

A flame atomic absorption spectrophotometer, followed by spike-and-recovery tests, was used to directly determine the levels of minerals in wine without the need for pretreatment. A stability test was also carried out by measuring a number of samples successively.

The recovery rates were found to be between 88 and 98%, while the stability was found to be 1.2% through the successive testing of the 40 samples. Both of these were considered to be promising results, indicating that flame atomic absorption spectrophotometry is a simple and accurate process through which to determine the levels of various minerals in wine.

The AA-7000 is furnished with a titanium burner head which is extremely resilient against corrosion. Additionally, it is simple to mount or dismount the air-cooled burner head in order to carry out cleaning, making maintenance work much easier.

This information has been sourced, reviewed and adapted from materials provided by Shimadzu Scientific Instruments.

For more information on this source, please visit Shimadzu Scientific Instruments.