HughPickens.com writes: Discovery News reports that dirty laundry smells bad because of certain chemicals called volatile organic compounds, which can't always be washed out on an eco-friendly 20C cycle. Researchers identified six volatile organic compounds (VOCs) on dirty t-shirts and socks. "The need to conserve the environment by reducing the wash temperature and the use of biodegradable washing products have grown in importance in the new millennium, making this type of research more high profile," says Professor John Dean. The researchers gave 6 men and two women a new pair of socks. They asked the volunteers to wash their feet with tap water and dry them before wearing the socks for at least 10 hours in a specified type of shoe. They then put each sock into a separate sample bag and stored them in the dark overnight. The researchers graded each sock and t-shirt on a scale of 0 (no malodor) to 10 (malodorous) by smelling them. To determine the chemicals present, samples were taken from each one. Items were then washed on a cold cycle using unscented detergent, and resampled before they were dried, at which point researchers took one final series of specimens. Following a method called static headspace-multi-capillary column-gas chromatography-ion mobility spectrometry (SHS-MCC-GC-IMS), six main VOCs were identified as the main culprits behind smelly clothing. Each one left its own scented signature. Butyric acid, for example, produced a rancid butter-like odor, while 2-heptanone created a banana-like fruity smell. "The work is fascinating as it links an everyday event -- the washing of clothes -- with cutting-edge research," says Dean. "In this particular research project we applied a new and innovative analytical technique for the detection of volatile compounds found in laundry items. We hope this provides a way of analyzing the effectiveness of different washing techniques."