Search tips
Search criteria 


Logo of aapspharmspringer.comThis journalToc AlertsSubmit OnlineOpen Choice
AAPS PharmSciTech. 2003 December; 4(4): 531–538.
Published online 2003 November 4. doi:  10.1208/pt040467
PMCID: PMC2750660

Thermal porosity analysis of croscarmellose sodium and sodium starch glycolate by differential scanning calorimetry


The aim of the study was to demonstrate the applicability of differential scanning calorimetry (DSC) on porosity analysis for cellulose and starch. Croscarmellose sodium (CCS) and sodium starch glycolate (SSG) were allowed to sorb moisture in 85%, 90%, 95%, and 100% relative humidity (RH) at 40°C for 24 hours. The pretreated samples were then subjected to DSC running temperature ranging from 25°C to −50°C at a cooling rate of 10°C/min. The cooling traces of water crystallization, if present, were transformed to porosity distribution via capillary condensation using Kelvin's equation. The porosity analysis of CCS and SSG was also done using nitrogen adsorption as a reference method. It was found that sorbed water could not be frozen (in cases of 85% and 90% RH) until the moisture content exceeded a cutoff value (in cases of 95% and 100% RH). The nonfreezable moisture content was referred to tightly bound, plasticizing water, whereas the frozen one may be attributed to loosely bound water condensation in pore structure of CCS and SSG surfaces. Not only capillary condensation but also the tightly bound, nonfreezable monolayer water lying along the inner pores of the surface contributed to porosity determination. Good agreement with less than 5% deviation of mean pore size was observed when the results were compared with nitrogen adsorption. The narrower pore size distributions, however, were obtained because of the limitations of the technique. It was concluded that pore analysis by DSC could be successful. Further research needs to be done to account for limitations and to extend the applicability of the technique.

Keywords: thermoporometry, differential scanning calorimetry (DSC), croscarmellose sodium (CCS), sodium starch glycolate (SSG)

Full Text

The Full Text of this article is available as a PDF (400K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
1. Sair L, Fetzer WR. Water sorption by starches. Ind Eng Chem. 1944;36:205–208. doi: 10.1021/ie50411a004. [Cross Ref]
2. Higuchi A, Iijima T. DSC investigation of the states of the water in poly(vinyl alcohol) membranes. Polymer. 1985;26:1207–1211. doi: 10.1016/0032-3861(85)90254-X. [Cross Ref]
3. Zografi G, Kontny MJ. The interactions of water with cellulose- and starch-derived pharmaceutical excipients. Pharm Res. 1986;3(4):187–194. doi: 10.1023/A:1016330528260. [PubMed] [Cross Ref]
4. Stern SA, Saxena V. Concentration-dependent transport of gases and vapors in glassy polymers. J Membr Sci. 1980;7:47–59. doi: 10.1016/S0376-7388(00)83184-1. [Cross Ref]
5. Mauze GR, Stern SA. The solution and transport of water vapor in poly(acrylonitrile): a re-examination. J Membr Sci. 1982;12:51–64. doi: 10.1016/0376-7388(82)80003-3. [Cross Ref]
6. Faroongsarng D, Peck GE. The swelling and water uptake of tablet III: moisture sorption behavior of tablet disintegrants. Drug Dev Ind Pharm. 1994;20(5):779–798. doi: 10.3109/03639049409038331. [Cross Ref]
7. Aharoni C. The solid-liquid interface in capillary condensation-sorption of water by active carbon. Langmuir. 1997;13:1270–1273. doi: 10.1021/la951007a. [Cross Ref]
8. Faroongsang D. The role of water sorption and, swelling by an insoluble tablet containing cellulose, starch, or their derivative as a disintegrant during aqueous coating simulation. West Lafayette, IN: Purdue University; 1993. pp. 134–139.
9. Cuperus FP, Bargeman D, Smolders CA. Critical points in the analysis of membrane pore structures by thermoporometry. J Membr Sci. 1992;66:45–53. doi: 10.1016/0376-7388(92)80090-7. [Cross Ref]
10. Filho GR, Bueno WA. Water states of Cuprophan (hemodialysis membrane) J Membr Sci. 1992;74:19–27. doi: 10.1016/0376-7388(92)87069-A. [Cross Ref]
11. Young JH, Nelson GL. Theory of hysteresis between sorption and desorption isotherms in biological materials. Trans Amer Soc Agric Eng. 1967;10:260–263.
12. Ishikiriyama K, Todoki M. Pore size distribution measurements of silica gels by means of differential scanning calorimetry. J Colloid Interface Sci. 1995;171:103–111. doi: 10.1006/jcis.1995.1155. [Cross Ref]
13. Ishikiriyama K, Sakamoto A, Todoki M, Tayama T, Tanaka K, Kobayashi T. Pore size distribution measurements of polymer hydrogel membranes for artificial kidneys using differential scanning calorimetry. Thermochim Acta. 1995;267:169–180. doi: 10.1016/0040-6031(95)02476-X. [Cross Ref]
14. Hay JN, Laity PR. Observations of water migration during thermoporometry studies of cellulose films. Polymer. 2000;41:6171–6180. doi: 10.1016/S0032-3861(99)00828-9. [Cross Ref]
15. Adamson WA. Physical Chemistry of Surfaces. 5th ed. New York, NY: John Wiley & Sons; 1990. Capillary condensation; pp. 661–666.
16. Flory PJ. Principle of Polymer Chemistry. Ithaca, NY: Cornell University Press; 1953. Partial molar quantities; pp. 511–518.
17. Van Dooren AA, Muller BW. Purity determinations of drugs with differential scanning calorimetry (DSC)-a critical review. Int J Pharm. 1984;20:217–233. doi: 10.1016/0378-5173(84)90170-4. [Cross Ref]
18. Gregg SJ, Sing KSW. Adsorption. Surface Area and Porosity. New York, NY: Academic Press; 1982. Use of the Kelvin equation for calculation of pore size distribution; pp. 136–138.
19. Ping ZH, Nguyen QT, Chen SM, et al. States of water in different hydrophilic polymers-DSC and FTIR studies. Polymer. 2001;42:8461–8467. doi: 10.1016/S0032-3861(01)00358-5. [Cross Ref]
20. Westermarck S. Use of Mercury Porosimetry and Nitrogen Adsorption in Characterisation of the Pore Structure of Manitol and Microcrystalline Cellulose Powders, Granules, and Tablets. Helsinki, Finland: University of Helsinki; 2000.
21. Ozeki S. Dielectric properties of water adsorbed in slitlike micropores of jarosite. Langmuir. 1989;5:181–186. doi: 10.1021/la00085a034. [Cross Ref]

Articles from AAPS PharmSciTech are provided here courtesy of American Association of Pharmaceutical Scientists