Page 4 - QAD-TOF syetem

Innovative fragmentation technology

Introduction of neutral radicals in positive and negative modes

The OAD-TOF system is equipped with an OAD RADICAL SOURCE I, which enables Oxygen Attachment Dissociation
(OAD) analysis, an innovative fragmentation that utilizes Shimadzu’s proprietary radical reaction. It can measure
fragment ions that cannot be obtained by conventional collision-induced dissociation (CID), where ions are fragment -
ed by collision with an inert gas such as argon or nitrogen. The irradiating oxygen radicals specifically oxidize/dissoci -
ate double bonds between carbons, which is useful for structure estimation of organic compounds such as lipids. The
technique can be applied to monovalent ions and negative ions, which have been difficult to fragment using radical
reactions by electrons and anions, and provides completely new structural information.

Radical source

Neutral radicals such as O/OH/H radicals are generated by microwave
discharge of raw material gases (water vapor and hydrogen gas) in a
vacuum. The neutral radicals are introduced into the OAD cell UFaccumulation ™
through a quartz tube. UFgrating ™ MCP

OAD cell
Precursor ions are reacted with neutral DL (Desolvation Line)
radicals generated in a radical source and UF-Qarray ™
What is OAD (oxygen attachment dissociation)?
fragmented. A collision gas (argon) can be
introduced, and conventional CID CID preferentially dissociates weak chemical bonds. In the case of lipids, CID can determine the basic structure of lipids and
UF-Lens ™
fragmentation is also possible by setting polar groups, and the carbon composition of side chains (number of carbons and double bonds). With OAD, oxygen
the collision energy (CE). radicals react specifically with the double bonds between carbons, causing dissociation. By measuring fragment ions
specific to the double bond, the position of the double bond can be determined.
UF-FlightTube ™
Quadrupole O PC 16:0_20:4(n-6, 9, 12, 15)
Precise temperature control is achieved O
due to an optimized heater and heater Sub-Interface N + O P − O O
sensor layout and a robust control system. Heated ESI Probe O H O
This minimizes the effects of any room O
OAD ON
temperature variations to enable stable [M + H] +
100
mass accuracy over long periods. It also 782.5682
reduces the time and trouble required for 75
608.3922 648.4234 688.4549 728.4861
mass calibration. n-15 n-12 n-9 n-6
% 50
iRef TOF ™ 25 566.3823
The unique electrode shape achieves an 500 525 550 575 600 625 650 675 700 725 750 775 m/z
ideal electric potential distribution that
OAD OFF
increases energy-focusing, while also [M + H] +
inhibiting trajectory divergence and flight 100 782.5702
time lengthening during ion reflection. 75
% 50
For LCMS-9050, click the button below. 25

Product 500 525 550 575 600 625 650 675 700 725 750 775 m/z

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