title: An automated system for monitoring and regulating the pH of bicarbonate buffers.
abstract: The bicarbonate buffer is considered as the most biorelevant buffer system for the simulation of intestinal conditions. However, its use in dissolution testing of solid oral dosage forms is very limited. The reason for this is the thermodynamic instability of the solution containing hydrogen carbonate ions and carbonic acid. The spontaneous loss of carbon dioxide (CO(2)) from the solution results in an uncontrolled increase of the pH. In order to maintain the pH on the desired level, either a CO(2) loss must be completely avoided or the escaped CO(2) has to be replaced by quantitative substitution, i.e. feeding the solution with the respective amount of gas, which re-acidifies the buffer after dissociation. The present work aimed at the development of a device enabling an automatic pH monitoring and regulation of hydrogen carbonate buffers during dissolution tests.
authors.affiliation: Physiolution GmbH, Walther-Rathenau-Strasse 49 a, 17491 Greifswald, Germany. ggarbacz@physiolution.eu
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Garbacz
authors.forename: Bartosz
authors.initials: B
authors.lastname: Kołodziej
authors.forename: Mirko
authors.initials: M
authors.lastname: Koziolek
authors.forename: Werner
authors.initials: W
authors.lastname: Weitschies
authors.forename: Sandra
authors.initials: S
authors.lastname: Klein
mesh_terms: D057205:Automation, Laboratory; D001639:Bicarbonates / Q000737:chemistry*; D002021:Buffers; D002245:Carbon Dioxide / Q000737:chemistry; D004867:Equipment Design; D005740:Gases; D006863:Hydrogen-Ion Concentration; D008838:Microcomputers; D008839:Microelectrodes; D008956:Models, Chemical; D012984:Software; D012995:Solubility; D013678:Technology, Pharmaceutical / Q000295:instrumentation* / Q000379:methods; D013997:Time Factors
chemical_list: D001639:Bicarbonates; D002021:Buffers; D005740:Gases; D002245:Carbon Dioxide