In order to evaluate the effect of chaotropic agents on proteoglycan and non-collagenous proteins, chicken xiphoid cartilage was treated with guanidine-HCl and MgCl2 in different concentrations (1M to 5M), and different periods of time (12, 24, 48 and 72hr). The maximum yield of uronic acid was obtained with 3M MgCl2 (73.3%). Concentrations of 4M and 5M of MgCl2 showed that much less Uronic acid was removed, 55.3% and 38.1% respectively. Extraction with 3MMgCl(2) and 3M guanidine-HCl resulted better efficiency when perfomed for 48 hr. Analysis by SDS-PAGE of the extracts obtained with guanidine-HCl and MgCl2 in different concentrations pointed out that most components are equally removed with the two solvents, showing that the extraction with MgCl2 is an alternative assay to remove non-collagenous proteins from extracellular matrix.8919397