Detection Equipment and Technology Evaluation to Counter the Threat of Fentanyl and Xylazine Act of 2024 or the DETECT Fentanyl and Xylazine Act of 2024 This bill provides statutory authority for the Department of Homeland Security's Science and Technology Directorate to take certain actions to support the detection of drugs such as fentanyl and xylazine. Specifically, the bill provides statutory authority for the directorate's research and development efforts to improve drug detection equipment and reference libraries for law enforcement agencies, including with respect to portable equipment, equipment that can analyze complex samples, and technology that uses artificial intelligence or other techniques to detect new substances. The bill additionally requires the directorate to follow certain standards and rely on certain information from the National Institute of Standards and Technology and the Drug Enforcement Administration, respectively, regarding these efforts.