Patent ID: 7709788

Claim:
A method for calibrating drift time for an ion mobility spectrometer that is open to the atmosphere, the ion mobility spectrometer including a gas ionization region with a sample gas inlet tube and sample gas outlet tube open to the atmosphere, a drift region with an inlet and outlet for a drift gas flow and pneumatically coupled to the ionization region, a charge collecting surface at the end of the drift region opposite the ionization region, and an electric field generator for providing an electric field between said ionization region and said charge collecting surface in order to transport ions in between, the method comprising: heating a solid phase sample of a calibrant chemical to produce a calibrant gas using a temperature controlled oven in pneumatic communication with said ionization region, wherein said calibrant chemical includes 5-nitrovanillin, also known as 4-hydroxy-3-methoxy-5-nitrobenzaldehyde, CAS number 6635-20-7; determining the drift time of ions of said calibrant chemical through said ion mobility spectrometer; and determining the expected drift time of a target chemical using a pre-determined ratio of the reduced mobilities of said target chemical and said calibrant chemical.