Date: Monday, March 6th, 2017 

Time: 11:00 AM 

Location: Building 4, Room 125​

Department of Chemistry, 

Stanford University, California,

USA      

Department of Chemistry, 

Stanford University, California, 

USA     

An important advance in mass spectrometry has been the introduction of ambient ionization sources in which ionization of the sample is accomplished in its ambient state at room temperature and atmospheric pressure external to the mass spectrometer. One of the leading forms of ambient ionization mass spectrometry has been that of paper spray ionization. Analyte ions are generated by applying a small volume of spray solvent to a paper support, which is normally held at high voltage. The analyte of interest can be premixed with the solvent spray or it can be applied to the paper prior to introduction of the solvent spray.  Paper spray mass spectrometry has enjoyed great success in analyzing complex mixtures.  I will describe a modification of paper spray mass spectrometry in which the paper support was replaced by a suitable organic-inorganic hybrid polymer whose porosity and chemical composition can be carefully controlled. The polymers chosen were organosiloxanes, which were prepared by the sol-gel process in which methyl-substituted alkylsiloxanes are hydrolyzed in the presence of a structure-directing porogenic reagent (CTAC, polyethylene glycol, or 1-ethyl-3-methylimidazolium ethyl sulfate) and an acid catalyst (hydrochloric acid).   Target drug compounds (lidocaine, sunitinib, and salbumatol) and seven narcotics in aqueous solutions, in blood, or in urine were used to demonstrate the utility of these polymers as solid sample supports and spray emitters.  Under the same conditions, a hydrophilic drug compound (geneticin) was detected by polymer spray but not by paper spray mass spectrometry.  Sample volumes of 1 to 2 µL were loaded onto the surface of these polymers, dried, and then sprayed from the polymer surface at 3-5 kV with methanol-water solvents. Organosiloxane polymer supports were found to the give a cleaner background, more ion signal, and less spread of the applied sample compared to paper supports for the same recording conditions. Moreover, organosilane polymer spray compared to paper spray offers a uniform surface that can be easily chemically modified, and which could be cleaned and reused, if desired. Some other variations of spray mass spectrometry will also be presented.

 

 

Richard N. Zare is the Marguerite Blake Wilbur Professor in Natural Science at Stanford University. Professor Zare is renowned for his research in the area of laser chemistry, resulting in a greater understanding of chemical reactions at the molecular level. By experimental and theoretical studies he has made seminal contributions to our knowledge of molecular collision processes and contributed very significantly to solving a variety of problems in chemical analysis. His development of laser induced fluorescence as a method for studying reaction dynamics has been widely adopted in other laboratories. Professor Zare has received numerous prestigious honors and awards among which are the 2011 King Faisal International Prize in Science and the 2000 Nobel Laureate Signature Award for Graduate Education, American Chemical Society. Professor Zare has given named lectures at numerous universities, has authored and co-authored over 800 publications and more than 50 patents, and he has published four books.