Electrical measuring cell for determinging ammonia, amines, hydrazine amines, hydrazine and hydrazine derivatives

US5344546A · kind A · utility

Assignee

• DRAGERWERK AKTIEGESELLSCHAFT · DE

Inventors

• Herbert Kiesele · Lübeck, DE
• Stephan Haupt · Lübeck, DE
• Uwe Kuhn · Riederich, DE

Key dates

• Filing date: Feb 19, 1993
• Grant date: Sep 6, 1994
• Expiry date: Feb 19, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02A50/20
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The invention is directed to an electrochemical cell for measuring ammonia, amines, hydrazine and hydrazine derivatives and includes a measuring electrode in an electrolyte. The measuring electrode is provided with a coating made of a transition metal oxide and is improved in that its measuring sensitivity during long-term loading is increased. The cross sensitivity of the measuring cell is reduced especially with respect to NO.sub.2 and SO.sub.2. For this purpose, the oxide constituents of the coating are made of a metal conducting oxide of one element or an oxide mixture of several elements of the platinum metal group. Oxides of ruthenium and iridium have proven especially useful. The invention is also directed to an electrochemical measuring cell for measuring ammonia or hydrazine and includes at least a measuring electrode and a counter electrode in an electrolyte. The measuring cell provides a signal increase having a shorter response time and an improved signal stability. For this purpose, the electrolyte is an aqueous solution of a hygroscopic salt of an alkali metal or alkaline earth metal such as calcium nitrate or lithium nitrate or a mixture of both salts.