Yongdong Wang Cerno Bioscience Office: 203-312-1150 x1151 FAX: 203-312-1159 E-mail: yongdong.wang@cernobioscience.com Job Title: Founder and President

Speaker: Yongdong Wang, Cerno Bioscience, 14 Commerce Drive, Danbury, CT 06810

Topic: Formula ID: Accurate Mass to Spectral Accuracy, FTMS to Quadrupole MS, and Internal Calibration to Self Calibration

Place: Building 549, Conference Room B, NCI at Frederick, Frederick, MD

Time: Tuesday, October 16, 2007, at 11:00 AM

Abstract: It is well known in the MS field that a 5ppm mass accuracy is required for elemental composition determination through mass spectrometry, typically from high resolving power instruments such as qTOF or FTMS. Through theoretical simulation, it will be demonstrated that there are still quite a few candidate formulas to choose from, even at 100ppb mass accuracy.

These candidate formulas, fortunately, have different isotope distributions which can be used to further distinguish among themselves. These differences, however, are typically not more than a few percent or in some cases less than 1% in relative terms, unless there exists a signature element such as Cl or Br. In order to discern the subtle difference in isotope distributions, a more comprehensive calibration involving both mass and peak shape has to be developed to attain the high (>99%) spectral accuracy necessary for unique elemental composition determination.

With the new MS calibration involving both mass and peak shape, a much higher mass accuracy can be attained on an otherwise conventional unit mass resolution systems, allowing for formula determination on even a single quadrupole MS. On higher resolution MS, the ability to use and accurately measure spectral accuracy to better than 1% makes the formula determination much less susceptible to mass errors, leading to unknown formula ID based on its own mass spectral response, without the use of either external or internal standard with known compositions, through a “self calibration” process.

Examples from single quadrupole, TOF, and OrbiTrap MS will be given to demonstrate these points.

The slides to this seminar are in a 1.1 Megabyte PDF file, which can be opened and read by using the free Adobe Acrobat Reader®.