The turbidimetric method for determination of chondroitin sulfate (CSA) with rivanol has been proposed by NÉMETH-CSÓKA. When CSA in the extracts of the whale nasal cartilage with 5% Na2CO3 was determined by this original method, the values were lower than those obtained by carbazol method (Table 2). In this paper, the cause was elucidated and the author established a modified method.
Chondromucoprotein (CMP), in which CSA is combined with “protein core” and therefore could be regarded as “combined CSA”, was prepared from the whale nasal cartilage by water extraction and “free CSA” from CMP. It was found that rivanol turbidity produced with “combined CSA” was much lower than that produced with “free CSA” (Fig. 1). As it is known that CMP is easily degraded into CSA and “ protein core” by alkali treatment, the effect of NaOH treatment of CMP on rivanol turbidity was examined (Fig. 2).
As the results, in determining CSA in CMP by rivanol turbidity method, it is necessary to treat the sample with 1% NaOH for 3 hours at 25°C for degradation of CMP, as a pretreatment. Determination of CSA in mixtures of “free CSA” and “combined CSA”, which were prepared from CSA and CMP, by this modified rivanol method gave a satisfactory result (Table 3).