Sociedad Europea De Analisis Diferencial De Movilidad

Alejandro Casado

Juan Fernandez De La Mora

Gonzalo Fernandez De La Mora

Guillermo Vidal-de-Miguel

Mario Amo

Daoiz Zamora

Improvements are provided in the detection of atmospheric vapors by ionizing them near ambient pressure, and analyzing them as ions. Lowest detection limits of parts per quadrillion (ppq) concentrations are enabled by a combination of improvements, including the use of a filter to remove occasional intense signal from explosive particles. Several sources of chemical background are identified and solutions for their reduction or elimination are presented. Gains in response time may be achieved by operating at elevated temperature. When the ionizer is an electrospray source, the use of high boiling point solvents is indicated. An increased selectivity is achieved by operating a differential mobility analyzer (DMA) in series with a mass spectrometer. However, ppq sensitivities require various improvements in the DMA system including a special coupling to the ionizer, controlling the temperature in the DMA pump circuit, avoidance of induction on the DMA electrodes from heating devices, etc.

Method for detecting atmospheric vapors at parts per quadrillion (PPQ) concentrations

A method for fast and accurate recognition of species contained in trace amounts in complex mixtures such as ambient air or biological fluids is taught based on the use in tandem of one or several differential mobility analyzers (DMAs) and possibly also a mass spectrometer (MS), all arranged in series. The two DMAs operate in different regions of the ion drag versus drift velocity curve (for instance, linear versus nonlinear regions), hence separating according to more than one independently discriminating parameters of the ion. Very high discrimination can be achieved even with a single stage of mass spectrometric separation by selecting a narrow range of ions with the DMA, and analyzing them in the MS, first without fragmentation, and then with fragmentation. This process does not require necessarily a tandem MS when fragmentation takes place in the inlet region of the MS. Fast and accurate discrimination is possible in single ion monitoring mode (SIM) for a large number of targeted species, even with relatively inexpensive and light single quadrupole MS systems, where the various filters placed in series would open pre-configured narrow windows suitable for passage of each ion in a list.

Growing community of inventors

Boecillo, Spain

Alejandro Casado