|Hall, Mary Beth|
|VAN SOEST, PETER - Cornell University - New York|
Submitted to: Animal Feed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2019
Publication Date: 5/3/2019
Citation: Hall, M., Van Soest, P.J. 2019. A modified method for preparing the lithium salt of chromium EDTA and comparison to the Binnerts method. Animal Feed Science And Technology. https://doi.org/10.1016/j.anifeedsci.2019.05.002.
Interpretive Summary: Liquid markers are used in dairy cattle nutrition research to measure how quickly liquid and nutrients pass or disappear from the rumen. A new method for synthesizing purified crystals of the liquid marker chromium (III) EDTA was developed because it was not possible to get the chemicals needed for the previous method. An older alternate method for producing chromium EDTA where the compound is not purified was also tested. Both the new and alternate method performed well, giving approximately 99% recovery of the chromium as chromium EDTA. This work provided an evaluation of a new method for producing a liquid marker that is relied on in nutrition research.
Technical Abstract: The objectives of this study were to develop an alternative method for preparing the lithium (Li) salt of chromium (III; Cr) ethylenediaminetetraacetic acid (EDTA; Cr-EDTA), and to evaluate the degree to which Cr is complexed with EDTA in a preparation in which Cr-EDTA is not crystallized for purification (Binnerts method). The new Li·Cr-EDTA preparation method which uses Cr acetate hydroxide rather than Cr acetate·H2O (Udén method) gave product yields of 90 to 87% which was similar to the 90% yield reported for the original preparation method. The Cr concentrations were 93 to 96% of that expected for the salt. Both the new preparation of Li·Cr-EDTA and the liquid preparation of the Binnerts method showed the same absorbance pattern at wavelengths from 330 to 700 nm with maximum absorption at 541 nm. Comparison to a Li·Cr-EDTA generated standard curve showed that the uncrystallized Cr-EDTA produced with the Binnerts methods gave a recovery of approximately 99%, which did not differ from a separate preparation of Li·Cr-EDTA. The new method for preparing Li·Cr-EDTA gave results comparable to the Udén method. In our study, the degree of Cr and EDTA complexation in the uncrystallized solution of the Binnerts method was comparable to the crystallized Li·Cr-EDTA.