NIST

Is the National Institute of Standards and Technology, a non-regulatory federal agency that promotes U.S. innovation and industrial competitiveness by developing and providing reliable measurement services and standards. NIST's research and development efforts focus on a wide range of scientific and technological areas, including physics, chemistry, engineering, and computer science. Their work plays a critical role in supporting the U.S. economy and ensuring the accuracy and reliability of measurements and standards used in various industries.
https://webbook.nist.gov/chemistry/