Biosorption of copper by wine-relevant lactobacilli.

Must and wine may be contaminated with elevated copper concentrations by the use of fungicides or in course of the vinification process. Hitherto only a few practicable and harmless procedures exist to reduce an excess of copper from must and wine. For this reason we investigated the biosorption of copper by eight wine-relevant Lactobacillus species. Both, living and heat-inactivated cells revealed a significant degree of Cu adsorption. It was shown that Cu binding correlated positively with an increasing pH value of the environment. The highest binding capacity of the tested lactic acid bacteria was found for L. buchneri DSM 20057 with a maximum of 46.17 µg Cu bound per mg cell in deionized water. In must, wine and grape juice Cu was removed less effective which is not solely attributed to low pH-values, but also to specific medium parameters such as intrinsic metal cations, organic acids or phenolic compounds. Nevertheless, about 0.5-1.0 µg Cu per ml could be removed from wine samples, which is sufficient enough to lower critical copper concentrations.

Forensic investigation of brick stones using instrumental neutron activation analysis (INAA), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF).

Brick stones collected from different production facilities were studied for their elemental compositions under forensic aspects using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF). The aim of these examinations was to assess the potential of these methods in forensic comparison analyses of brick stones. The accuracy of the analysis methods was evaluated using NIST standard reference materials (679, 98b and 97b). In order to compare the stones to each other, multivariate data analysis was used. The evaluation of the INAA results (based on the concentrations of V, Na, K, Sm, U, Sc, Fe, Co, Rb and Cs) using principal component analysis (PCA) and cluster analysis is presented as an example. The results derived from the different analytical methods are consistent. It was shown that elemental analysis using the described methods is a valuable tool for forensic examinations of brick stones.