Direct detection of silver nano particles in biological and environmental samples

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Nanotechnology is still an emerging area in research and industry and so far several hundreds of different consumer products include nanomaterials. About a fifth of all consumer products comprise silver nanoparticles. Silver nanoparticles are often added to cosmetics, hygiene, and health care products as well as in food and food contact materials. Their broad application requires a new assessment of silver, i.e. silver nanoparticle risk to human health and environment. However, official bodies are unable to give a definite opinion on basis of the currently available data. For this purpose more data has to be gained and large sample series are to be studied. In this context, there is an urgent need for reliable and robust analytical methods for nanoparticle detection, especially in complex sample matrices and large sample series. In addition, from December 2014 on, labelling of nanomaterials in food will be mandatory in the EU. Hence, controlling this obligation will require suitable analytical methods. Several approaches are currently objects of research and are discussed in detail in the state-of-the-art of the present proposal. In the planed project, a new method will be developed, allowing fast and cost-effective screening of large sample series for the presence of silver nanoparticles. In particular the developed method will be able to detect directly and selectively silver nanoparticles in solid complex matrices without elaborative sample preparation. This will be achieved by application of direct solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry. In preliminary experiments we could show that atomisation delay and atomisation rate are significant indicators for the presence of silver nanoparticles. In the planed project this approach will be further pursued in order to develop a new method for detection and distinction of silver nanoparticles and silver ions in relevant solid and complex liquid samples. The advantages of such an approach are obvious: The analytical process is shortened, because sample preparation is minimised to sample homogenisation. Extraction or separation of nanoparticles from the matrix is unnecessary. Hence, a higher samples throughput is achieved, no reagents are required and no chemical wastes for disposal occur. This makes the method economical and ecological beneficial (green analytical chemistry; sustainability). Moreover, no manipulation of the original samples occurs which minimises undesired transformation of the nanoparticles in the course of the analytical procedure.