National Research Laboratories 1 article published in JoVE Environment Clean Sampling and Analysis of River and Estuarine Waters for Trace Metal Studies Kuo-Tung Jiann*1, Liang-Saw Wen*2,3, Peter H. Santschi4 1Department of Oceanography, National Sun Yat-sen University, 2Institute of Oceanography, National Taiwan University, 3Taiwan Ocean Research Institute, National Research Laboratories, 4Department of Oceanography and Marine Sciences, Texas A&M University at Galveston Special care using "clean techniques" is required to properly collect and process water samples for trace metal studies in aquatic environments. A protocol for sampling, processing, and analytical procedures with the aim of obtaining reliable environmental monitoring data and results with high sensitivity for detailed trace metal studies is presented.