Georg Becher has more than 30 years of continuous involvement in structural characterisation and chemical analysis of organic compounds. His present main focus is on human exposure assessment for organic pollutants through the use of chemical biomarkers. He directs research and development of analytical techniques for the determination of trace amounts of organic pollutants in human samples. State-of -the-art analytical methods are employed such as gas chromatography-high resolution mass spectrometry and liquid chromatography-triple stage mass spectrometry. The methods have been applied for biomonitoring persistent organic pollutants, such as dioxins, PCBs, brominated flame retardants and perfluorinated alkyl substances in breast milk and blood. Further, methods are developed for the determination of transformation products of reactive and easily metabolised compounds in urine.