1.1 ,This practice covers uniform procedures to develop, select, collect, prepare, and use oxidized, relatively unpolluted, aquatic natural-matrix bed-sediment reference samples for the collaborative testing of chemical methods of analysis for sediments and similar materials. Reference samples prepared using this practice are intended for use as natural sediments, analyzable for major, minor, and trace elements, and general physical/organic analyses only. The samples are not designed or tested for environmental pollutants such as trace organic compounds.