To Örebro University

Soil is one of the vehicles by which metals enter plants and ground water. Compared to organic pollutants, metals do not biodegrade and are usually not mobile. In order to estimate the potential impact on ground water, the amounts of extractable metals from soil are thus of concern.

Soil matrices may represent a quite complex matrix, thus the appropriate choice of sample preparation and analytical method is of great importance and challenging to ensure reliable and fast data, and keeping labour and time need as low as possible.

To quantitatively determine bioavailable metals, selected soil samples were dried and homogenised, then extracted using acetic acid (c = 0.1 mol/L). These extracts were then analysed on the one hand using classical analytical methods, such as titrimetry (complexometry) and spectrophotometry as well as the other hand by instrumental methods, including inductively-coupled plasma optical emission spectrometry (ICP-OES) and inductively-coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GF-AAS), in order to investigate their applicability for the determination of certain soil pollutants, which may have a negative impact on the environment, animals and humans, when entering water bodies.

Regarding the methods, ICP-OES and ICP-MS are multi-element methods offering advantages like low detection limits, good precision and repeatability, but suffer from drawbacks, like high costs due (ultra clean laboratory, supra pure chemicals, high argon consumption) and low tolerance to high matrix loading. This drawback is minimised using GF-AAS, which conversely is only a single-element method, but giving the possibility to overcome problems with concentrations below limits of detection (LOD) due to repetitive sample introduction. The classical methods are characterised by higher LODs, but applying specific reagents precise measurements with low interferences even in complex matrices can be obtained by photometry. Titrimetric methods can be used not only for specific single element determination, but also for determining the sum of certain metals.