If you have to ship a sample of waste to a laboratory for analysis, that sample is exempt from RCRA regulations per 40 CFR 261.4(d). The exemption is valid throughout the entire cycle starting from sample collection, storage prior to shipping, shipment, lab storage prior to analysis, analysis, and return shipment of excess sample to the sample collector. It means that the sample collector does not need to use a hazardous waste manifest to ship the sample even if it is hazardous (listed, reactive, ignitable, corrosive or toxic). The same goes for samples that you ship to a lab for treatability studies.
Note that if the sample “leaves” the cycle at any point, the exemption ceases to exist. For example, if the lab decides to dispose of the excess sample, the sample exits the cycle and it becomes a solid waste and the lab must determine if it is a hazardous waste. Likewise when the excess sample reaches the sample collector, the cycle ends and the collector must dispose of the sample in accordance with RCRA regulations.