In situ determination of calcium carboxymethylcellulose on a cellulose film via ion exchange
✍ Scribed by H. H. Chen
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 392 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
A simple and rapid ion exchange method is presented for the in situ determination of calcium carboxymethylcellulose (CaCMC) on a cellulose film. The method is based on the ion-exchange reaction between the calcium ion in CMC and a large quaternary ammonium ion, such as hexadecyltrimethylammonium ion, followed by a second ion exchange reaction in which the quaternary ammonium ion is displaced by 3,9-bisdimethylaminophenazothionium ion. The development of a blue color allows for the determination of the CaCMC distribution on the film by using a scanning densitometer. The reasons that CMC prefers a relatively large quaternary ammonium ion to the divalent calcium ion are suggested. This method is also applicable for the determination of sodium carboxymethylcellulose on a cellulose film where it is only necessary to carry out the second ion-exchange reaction. The minimum detection limit for a CaCMC (degree of substitution is 0.7) coating is at least 1 pg/cm2.