a. Nanospray mass spectrum of tetraplex labeled dp4 SEC-HPLC fraction corresponding to [1,1,2,2,2] [Δ-UA, UA, GalN, Sulfate, Acetyl] . b. Relative quantities per μg protein of the dp4 fraction of three proteoglycans and cartilage extract determined using: nanospray mass spectrometry of stable isotope coded samples; and SEC-HPLC of unlabeled samples at an absorbance of 232 nm. c. Relative glycoform quantities as determined by: nanospray tandem mass spectrometry of tetraplex labeled dp4 samples; d. CE-LIF disaccharide analysis of exhaustively digested chondroitin chains.