Development of multiplexed and miniature mass spectrometers

Sameer Subhash Kothari, Purdue University


The objective of the projects described in the following chapters is the development of new multiplexed and miniature rectilinear ion trap mass spectrometers. The first project, described in chapter 2, is the development of an ESI mass spectrometer coupled with an atmosphere interface and using RIT as the analyzer. The development object is to demonstrate the possibility of using a RIT for the analysis of biological compounds, and furthermore to prove the concept of using RITs in the multiplexed instrument with an atmospheric pressure interface. Design, characterization and applications of a novel multiplexed, four channel mass spectrometer using RIT mass analyzer is described in chapter 3. This instrument is the first example of a fully multiplexed, four channel mass spectrometer with atmospeheric pressure interface with all the four channels operating simultaneously. This instrument increases the versatility of multiplexed instruments by adding the capability of detecting positive as well as negative polarity ions generated by ESI and atmospheric pressure chemical ionization (APCI) sources simultaneouosly. It is desirable to develop techniques to analyze involatile and thermally unstable compounds from large surface area with rapid response time, preferably without special sample preparation. Explosives present special problems for MS due to their great range of volatilities while their occurrence on surfaces makes their direct ionization difficult by traditional methods. The high electron affinities associated with the nitro or nitrate functional groups present in the overwhelming majority of explosives in common use mean that they readily form negative ions by electron capture. Therefore a mass spectrometer capable of detecting the negative ion species feature lower limits of detection and a greater range of analysis than if it were only capable of detecting positively charge explosive ions. Chapter 4 describes development of a miniature mass spectrometer with negative ion detection capability which can analyze explosives directly from surfaces without any specialized sample preparation.




Cooks, Purdue University.

Subject Area

Analytical chemistry

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