[en] This report presents the results from analyses of samples taken from the headspace of waste storage tank 241-U-104 (Tank U-104) at the Hanford Site in Washington State. Tank headspace samples collected by Westinghouse Hanford Company (WHC) were analyzed by Pacific Northwest National Laboratory (PNNL) to determine headspace concentrations of selected non-radioactive analytes. Analyses were performed by the Vapor Analytical Laboratory (VAL) at PNNL. Vapor concentrations from sorbent trap samples are based on measured sample volumes provided by WHC. No analytes were determined to be above the immediate notification limits specified by the sampling and analysis plan. None of the flammable constituents were present at concentrations above the analytical instrument detection limits. Total headspace flammability was estimated to be <0.108% of the lower flammability limit. Average measured concentrations of targeted gases, inorganic vapors, and selected organic vapors are provided in a table. A summary of experimental methods, including sampling methodology, analytical procedures, and quality assurance and control methods are presented in Section 2.0. Detailed descriptions of the analytical results are provided in Section 3.0