Released in early 2016, our Dual Polarity Ion Source (DPIS) enables SIFT-MS to be extended to real-time detection of acid gases – including sulfur dioxide (SO2) and sulfur trioxide (SO3) – via negatively charged ionization.
The table summarizes how easily SO2 and SO3 are resolved using either of the negatively charged reagent ions OH– or O2–. The reaction rate coefficients for three of these reactions are fast, enabling SO2 and SO3 to be sensitively analyzed to sub-ppbv levels directly from air within a few seconds.
|Reagent ion||Product ion and m/z (in Daltons)||Rate coefficient, k|
(in cm-3 mole-1 s-1)
|Sulfur dioxide (SO2)|
|OH–||SO2.OH–, m/z 81||1.0×10-10 *|
|O2–||SO2–, m/z 64||3.0×10-9|
|Sulfur trioxide (SO3)|
|OH–||SO3–, m/z 80||1.6×10-9|
|O2–||SO3–, m/z 80||1.5×10-9|
* This rate coefficient has been converted from a three-body reaction rate coefficient to a pseudo first-order rate coefficient under the standard operating conditions when using nitrogen carrier gas in Syft Technologies’ Voice200ultra Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) instruments.
Through the groundbreaking advance of rapidly switchable dual-polarity ionization, SIFT-MS more than ever provides comprehensive stack and continuous emissions monitoring solutions.