108641-83-4

DL-Cystine-d₄ is intended for use as an internal standard for the quantification of cystine by GC- or LC-MS. DL-Cystine is a racemic mixture of D- and L-cystine. D-Cystine is an inactive enantiomer of L-cystine , an oxidized form of cysteine .¹

1. Baker, D.H., and Harter, J.M. D-cystine utilization by the chick Poult. Sci. 57(2),562-563(1978).