Evaluation of separation and determination of phytoavailable and phytotoxic aluminium species fractions in soil, sediment and water samples by five different methods

The suggested research deals with the separation of phytoavailable and phytotoxic aluminium species fractions in soil, sediment and water samples by five different procedures (single and sequential extractions, membrane filtration, chelating solid phase extraction and kinetic strength discrimination method). The concentrations of Al in studied samples and relevant plant materials were measured by flame atomic absorption spectrometry (FAAS), optical emission spectrometry with inductively coupled plasma (ICP OES) and UV/visible (VIS) spectrophotometry. The used separation procedures can be divided into three groups. The first group is consisting of weakly efficient single extraction procedures by H2O, dilute acetic acid, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), salicylic acid, ammonium salicylate and 8-hydroxyquinoline, chelating solid phase extraction by resins Iontosorb Oxin and salicyl and kinetic strength discrimination method using 8-hydroxyquinoline which release from the samples only small amounts of phytoavailable and phytotoxic Al by ion-exchange or complexation processes. The more efficient extractions with KCl, NH4Cl, CaCl2, BaCl2, CuCl2, LaCl3, NH4F and (NH4)2C2O4 leach approximately the same amounts of phytoavailable Al as the total Al concentrations in plant material (grass Festuca rubra) growing on analysed soils and sediments. The third group of separation procedures contains the most aggressive leaching with Na4P2O7, dilute HCl, NH2OH · HCl in HNO3 and H2O2/ammonium acetate in HNO3. These extractants release the highest amounts of Al from solid samples, approximately 2–4-fold as the total Al concentrations in relevant plant material and they are unsuitable for purpose of this study.