Paweł KOŚCIELNIAK is a full professor at the Jagiellonian University, Faculty of Chemistry, Krakow, Poland. He is a member of the Committee of Analytical Chemistry of the Polish Academy of Sciences. The main areas of his scientific interest are flow analysis, forensic chemistry, and environmental analysis. He is involved in the development of novel analytical methods and procedures with special attention paid to such fundamental analytical issues as analytical calibration, examination and elimination of interference effects, optimization and validation procedures, and two-component analysis. He is the author of more than 300 articles on these issues.