Ion Mobility Spectrometer (IMS)
Handheld IMS can identify dangerous chemicals
Ion mobility spectrometers (IMS) are suitable for the chemical analysis of hazardous substances. They are characterized by low detection limits, short response times and the detection of different chemical substance classes. Mobile ion mobility spectrometers, such as the ChemProX, can be used to detect traces of hazardous substances directly on site.
The ChemProX uses open loop technology. Unlike standard IMS instruments, this special design allows sample input, ionization, drift phase and detection to occur continuously.
Open Loop technology increases selectivity of ion mobility spectrometers
In ChemProX, the detectors are integrated into the walls of the drift tube. The ions are deflected toward the walls of the drift tube, which also serve as detectors. In this method, the size of the ions is not measured by the drift time, but by the penetration depth of the ions into the tube, i.e. small ions enter deeper than larger ones. The time at which the ions enter the drift tube is no longer relevant and the measurement can be made continuously. This makes the ChemProX less susceptible to interfering substances.
The detectors are replaced by MOS (metal oxide semiconductor) sensors. When an ion hits the surface of the MOS sensor, its polarity (positive or negative charge), trajectory and change in polarity is measured at the sensor. These independently operating sensors (orthogonal sensors) significantly reduce the false alarm rate. Each measured signal about the size of the ion, can additionally be further distinguished according to its polarity and chemical properties (MOS sensor). Thus, two ions with the same signal for size can additionally be distinguished by further parameters, which significantly increases the selectivity of the ChemProX.