Day 2 :
National Institutes of Health, USA
Keynote: The role of mass spectrometry in improving the diagnosis and management of adrenal diseases
Time : 10:00-10:30
After addressing several new findings which result in optimization of steroid profile measurement, the talk will focus on how mass spectrometry improves both diagnosis and treatment of patients with adrenal diseases (24 million people in the USA). The less than optimal use of serial cortisol measurements following ACTH stimulation to diagnose and treat adrenal disorders will be addressed. Replacement of cortisol by 11-DOC is preferable and in a fairly high percentage of cases (15–30%) disagrees with the diagnosis obtained using cortisol.
Time : 10:30-11:00
Mass spectrometry has long been applied to study inorganic vapors at high temperatures. Such measurements lead to a variety of useful information including thermochemical data on the both the vapor itself and condensed phase vapor source, identity of the vapor species above a particular condensed phase, and bond energies of the vapor species. However, sampling of high temperature vapors presents a series of unique challenges. Paricular care must be taken to have a clear, unobstructed path to the ionizer. In this paper, we describe the sampling system used at NASA Glenn and also a recently developed Monte Carlo simulation of this sampling system. The vapor source is a Knudsen cell, heated to temperatures up to 2000°C. An orifice in the cell of well-defined geometry forms a molecular beam, which is directed through a series of aperatures into the mass spectrometer ionizer. Following the method of Chatillon and colleagues, the first aperture has a smaller diameter than the Knudsen cell orifice so that the ionizer effectively ‘sees’ only into the cell, thus minimizing the effects of background gases. A second aperature further directs the molecular beam into the ionizing region. This molecular beam portion of this process can be modeled with a simple Monte Carlo simulation. Trajectories begin in the Knudsen cell and are traced through, till either the molecule leaves the sampling region or reaches the ionizer. This code allows optimization of aperature diameters and spacings as well as estimation of the efficiency of the sampling process. Future ideas are presented for high sensitivity measurements of inorganic vapors.
SABIC Technology Center, Saudi Arabia
Keynote: Further investigation of the adduct ion complications on MRM at different LC-MS/ MS ionization techniques, ESI, APCI, MMI and APPI
Time : 11:15-11:45
Wenjie Cao received a PhD from Professor John Calvin Giddings’ Group at the University of Utah, Salt Lake City, UT. He is a Contributor to the book, “Encyclopedia of Chromatography” and more than 20 publications and presentations in peer-reviewed scientific journals and international conferences. He has worked for Huntsman Polymers Corp, Sealed Air, and DuPont as a Research Investigator for 14 years in USA before joined SABIC in 2012. He is now the Technical Leader of chromatography and wet lab and a Staff Scientist of the Analytical Department of the SABIC Technology Center at Riyadh. He has filed six patents, delivered talks and made seminar presentations in the ISPAC Symposium, 2016 and in King Saud University since he joined SABIC Technology Center.
This presentation is going to extend the comparison of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to multimode ionization (MMI) and atmospheric pressure photo ionization (APPI) per some of the audiences’ request during the Q&A section of my presentation during the 2015 International Summit on Current Trend of MS in New Orleans. For the triple quadrupole LC-MS/MS instrument, the primary purpose or the most significant feature is the highest sensitivity among almost all, if not all of the LC-MS/MS instruments by doing the multiple reaction monitoring (MRM) testing. Ionization efficiency, selectivity, adduct ion production are among the top parameters which affect the MRM testing and the sensitivity. From ESI to APCI to MMI and APPI, this presentation will show that the species and amount of adduct ions produced at each mode are quite different. Some type of the adduct ions may complicate the MRM testing by decreasing the sensitivities while some other adduct ions may prevent any reliable MRM tests being performed. Some examples will be presented to show how the typical adduct ions are produced in each mode from ESI to APCI and APPI, and how the typical adduct ions may complicate the MRM testing. The overall pros and cons, and the best ionization mode for some type of the targeted chemicals will be summarized for the different ionization techniques.