IAEA-C7 oxalic acid was prepared by mixing natural oxalic acid which was purchased from the Vaishali company, Aurangabad, India, and synthetic oxalic acid purchased from Rhone Poulenc by recrystallization at Chemie Uettikon GmbH, Lahr, Germany in a certain proportion . The recommended value of the quality control material is the result of the statistical evaluation of an interlaboratory comparison .
(SD) Standard uncertainty at 1 sigma level
(R/I/C) Classification assigned to the property value for analyte (Recommended/Information/Certified)
le Clercq, M., van der Plicht, J., Gröning, M. (1998): New 14C reference materials with activities of 15 and 50 pMC. Proceedings of the 16th International 14C Conference, edited by W. G. Mook, J. van der Plicht. Radiocarbon, 40 (1), 1998, 295-279.