Automated Karl Fischer titration apparatus and method - Patent Articles

United States Patent 5,340,541
Jackson , et al. August 23, 1994
Automated Karl Fischer titration apparatus and method
Abstract
Automation of the coulometric Karl Fischer titration has allowed for the accurate, precise determination of moisture content of lyophilized hGH formulations. The system of the present invention utilizes a vented, two-hole sampling/dispensing probe that dispenses titrant and withdraws sample solution through the closed container rubber septum into the Karl Fischer titration reaction vessel. This approach eliminates erroneous results due to environmental moisture contamination or loss of material during the sample transfer process. The system of the present invention is also equipped with a fixed loop valving system, which facilitates the precise measurement of a defined amount of water as a standard. This allows for an accurate accessment of system suitability that was lacking with commercial water standards due to inaccurate moisture content presumably from moisture contamination of the standard under storage and/or at the time of manufacture. The use of the automated system of the present invention has led to a more complete understanding of the role of moisture content on hGH stability and this technology is applicable to other pharmaceuticals where an accurate moisture content determination is needed.
Inventors: Jackson; David A. (Fishers, IN); Riggin; Ralph M. (Indianapolis, IN); Towns; John K. (Indianapolis, IN)
Assignee: Eli Lilly and Company (Indianapolis, IN)
Appl. No.: 027254
Filed: March 5, 1993
Current U.S. Class: 422/75; 205/788; 422/81; 436/42; 436/51
Intern'l Class: G01N 031/16; G01N 033/18
Field of Search: 422/63,64,67,68.1,75,100,103,104,81 436/42,51 204/153.22