/ RAW MATERIALS / Malt / AAS of Minerals

R-205.34.210 [2016-03] Determination of Metals in Wort – ICP-AES or ICP-OES

Minerals and trace elements (e.g., K, Ca, Na, Mg, Fe, Cu, Zn, Mn) play a significant role in beer production and in product quality.

This group of elements is important, e.g., for yeast growth, and therefore for fermentation. However, if concentrations are too high, particularly of heavy metals, this may have very adverse effects on the stability and sensory properties of the beer. For this reason, mineral analysis may be helpful when problems arise. Elements such as potassium and magnesium are also important for human nutrition. Typical analysis techniques such as gravimetry, complexometry and colorimetry are either too imprecise or involve complex procedures and are very time-consuming. Atomic absorption spectrophotometry or atomic emission spectrometry with inductively coupled plasma (ICP-AES or ICP-OES) represent an elegant, rapid and very precise analysis technique.

Generally speaking, the following methods are suitable for use with Congress wort samples.

Atomic Absorption Spectrophotometry (AAS) is based on the phenomenon of resonance absorption.

An element-specific light source (e.g. hollow cathode lamp or gas emitting lamp) radiates through a space (e.g. flame or absorption cuvette) containing the absorption medium, namely the metal of the element to be measured, in a vaporized form. This method is based on the fact that radiant energy causes the excitation of atoms from their base orbitals, which then absorb specific frequencies of light, resulting in characteristic spectra. The reduction in the resonance energy is proportional to the concentration of the element present and is separated from the other frequency lines originating from the light source by a monochromator. These are then further transformed by a detector to an electrical signal, which is displayed digitally or recorded.

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atomic absorption spectrometer

Application/Purpose

All of the following minerals (Fe, Na, K, Ca, Mn, Zn, Cu, Mg, Al and Sn) can be determined either simultaneously or sequentially with this analytical technique.

Scope of Application

Suitable for analysis of all (laboratory) wort samples

Principle

Atomic emission spectroscopy, also known as optical emission spectroscopy, in conjunction with inductively coupled plasma (ICP-AES or ICP-OES) is a technique used to determine and measure elements based on the phenomenon of atomic emission. The solutions to be analyzed are nebulized and the resulting aerosol is transported with the help of a carrier gas into an inductively coupled plasma (ICP). There, the elements are excited to a higher energy state, causing emissions. The spectrometer separates these emissions into individual wavelengths, and the intensities of the spectral lines of the element are measured with detectors (photomultipliers). A qualitative measurement is possible by calibrating the instrument with reference solutions, whereby a linear relationship exists over a broad range (generally several orders of magnitude) between the intensities of the emission lines (spectra) and the concentrations of the elements.