MULTIPURPOSE ELECTROCHEMICAL MASS-SPECTROMETRY - A NEW POWERFUL EXTENSION OF DIFFERENTIAL ELECTROCHEMICAL MASS-SPECTROMETRY

In previously reported setups for differential electrochemical mass sp ectrometry (DENIS), the mass spectrometer was usable only for this app lication. The present publication describes a novel setup which overco mes this Limitation using a dual inlet system. One inlet is connected to a vacuum recipient at which the electrochemical cell is attached wh en operating in the DEMS mode. The other one consists of a capillary i nlet which can be used for various mass spectrometry applications. Wit hout the necessity of shutting down the vacuum system, it is possible to switch modes by just opening and closing two valves. The present pu blication describes the connection to a thermogravimetric analyzer (TG A) via the capillary inlet. Using this setup, it is possible to detect thermal decomposition products as a function of temperature in additi on to the determination of the weight loss. Additionally, the characte ristic response time of the multipurpose electrochemical mass spectrom etry (MPEMS) operating in the DEMS mode has been substantially improve d compared to previous setups (20 to 50 ms in comparison to 200 to 500 ms). Thus, higher scan rates than the typical 10 to 25 mV/s are now p ractical. Using sputtered electrodes, scan rates as high as 1000 mV/s can be applied. As indicated by the features described above, MPEMS is a versatile instrument with a wide range of applications not only in electrochemistry, but also in general analytical chemistry.