analysis | Odour and emissions Right:
Fraunhofer’s SAFE (Solvent Assisted Flavour
Evaporation) apparatus is
used to extract odorants from plastics and polymers
the Council Directive 1999/13/EC [VOC Solvents Emission Directive] on the limitation of emissions of VOCs from the use of organic solvents in certain activities and installations. These actions were initially focused on certain production processes and then expanded to include products and their emissions – for paints and automotive finishes and subsequently for cosmetics, cleaning products and adhesives also. However, plastic compounds emitting VOCs have not yet been a major objective of EU legislation,” he explains. Erika Zardin, Manager of Fraunhofer IVV’s Product
Performance business area and an expert on environ- mental analysis and online gas phase monitoring, adds that that current main areas of research interest for plastics are in building materials and air quality relating to vehicle interiors. “These are addressed by a range of analytical methods encompassing micro-extraction techniques for sampling VOCs and electronic noses, along with human assessment of odours. With this background, it is now important to expand the knowl- edge database and analytical arsenal to provide an overview of all plastic materials emitting VOCs in consumer products,” she says.
Odour characterisation Fraunhofer IVV believes there is a growing demand from industry for the characterisation of unintended or disturbing odour emissions from daily use articles such as children’s products, leisure and sports equipment, and home-use products including furniture and home textiles. “We have developed a method – based on the well-established odorant analysis techniques commonly used in food flavour research – to search for and identify off-odours causing substances in complex non-food matrices, such as polymer materials. Due to our improved methodology, we are able to chemically identify sources of off-odours and make informed suggestions for developing avoidance strategies,” says Buettner. The first step in this new analytical protocol is to
obtain an objective description of the sample’s smell. “This can usually be done by human-sensory evaluation of the affected product by a trained panel. Odorants are then extracted from the sample using organic solvents, with non-volatile matrix constituents separated by solvent-assisted flavour evaporation, a new and versatile technique for the careful and direct isolation of aroma compounds from complex food matrices. The extract is then concentrated by means of Vigreux and micro-distillation. To identify the odorants, the extract is analysed using one- and two-dimensional gas chroma- tography and mass spectrometry/olfactometry.” Buettner says the combination of traditional analytical methods with the evaluation of eluting
22 COMPOUNDING WORLD | January 2017
substances by trained accessors enables sensitive and selective detection of odorants. “So far, we have used this methodology to identify odorants in a variety of non-food matrices, such as plastic toys for children, food contact materials made from silicone and post-consum- er plastic waste. Recycled polymers, wood, adhesives, and pigments have also been successfully analysed.” Issues relating to the sensory effects of articles in
daily use are an increasing area of research being addressed by the Fraunhofer IVV group and this includes, for example, the characterisation of misbal- anced or unwanted smells in packaging materials and consumer products. “In this area we are currently drafting several publications on products and materials of daily use - two of which address the issue of offensive and irritating smells in children’s toys,” Wiedmer says. Meanwhile, Zardin sees a multitude of research topics
ahead. “We see an increasing demand and obligation for scientists – such as chemists with exceptional analytical skills – to address these emerging and expanding issues,” she says. “When analysing plastic materials with sophisti- cated methodologies, as undertaken in our odorant research, the next logical step is to also target other unintended or intentionally administered substances that have an undesirable presence in these materials. At
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