Secondary electrospray ionization (SESI) of ambient vapors for explosive detection at concentrations below parts per trillion.
We determine the sensitivity of several commercial atmospheric pressure ionization mass spectrometers towards ambient vapors, ionized by contact with an electrospray of acidified or ammoniated solvent, a technique often referred to as secondary electrospray ionization (SESI). Although a record limit of detection of 0.2 x 10(-12) atmospheres (0.2 ppt) is found for explosives such as PETN and 0.4 ppt for TNT (without preconcentration), this still implies the need for some 10(8)-10(9) vapor molecules/s for positive identification of explosives. This extremely inefficient use of sample is partly due to low charging probability ( approximately 10(-4)), finite ion transmission, and counting probability in the mass spectrometer (1/10 in quadrupoles), and a variable combination of duty cycle and background noise responsible typically for a 10(3) factor loss of useful signal.
Martínez-Lozano
Pablo
P
Mechanical Engineering Department, Yale University, New Haven, CT, USA.
Rus
Juan
J
Fernández de la Mora
Gonzalo
G
Hernández
Marta
M
Fernández de la Mora
Juan
J
D001274:Atmospheric Pressure; D053834:Explosive Agents / Q000032:analysis*; D010417:Pentaerythritol Tetranitrate / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014303:Trinitrotoluene / Q000032:analysis; D035501:Uncertainty
D053834:Explosive Agents; D010417:Pentaerythritol Tetranitrate; D014303:Trinitrotoluene