An ion mobility separator or spectrometer is disclosed comprising an inner cylinder and an outer cylinder defining an annular volume through which ions are transmitted. Spiral electrodes a-f are arranged on a surface of the inner cylinder and/or on a surface of the outer cylinder. A first device is arranged and adapted to maintain a DC electric field and/or a pseudo-potential force which acts to urge ions from a first end of the ion mobility separator or spectrometer to a second end of the ion mobility separator or spectrometer. A second device is arranged and adapted to apply transient DC voltages to the one or more spiral electrodes in order to urge ions towards the first end of the ion mobility separator or spectrometer. The net effect is to extend the effective path length of the ion mobility separator.

This invention provides methods and biomarkers for diagnosing autism by identifying cellular metabolites differentially produced in autistic patient samples versus non-autistic controls. Methods for identifying a unique profile of metabolites present of secreted in brain tissue, cerebrospinal fluid, plasma, or biofluids of autistic samples are described herein. The individual metabolites or a pattern of secreted metabolites provide metabolic signatures of autism, which can be used to provide a diagnosis thereof.

A system and methodology for the detection of threat substances is described. The detector system consists of a method to evaporate the sample into a primary separator and thermal release of trapped target materials into a secondary separator like conventional GC. The GC column is thermally ramped to elute all substances and the end of the column terminates into an atmospheric pressure chemical ionization source of an axial ion mobility spectrometer (AIMS). Both polarity ions are pulsed into a single construction separator tube at different timing. Their arrival time is detected on a collector plate, which allows registering their ion mobility spectra of both polarities for a single GC peak.

A field terminator includes a plurality of electrode plates positioned around a guide axis at a radial distance therefrom. The plates generate a quadrupole DC field such that a polarity on each plate is opposite to a polarity on the plates adjacent thereto. The plates may be positioned at an axial end of a quadrupole ion guide such as a mass filter. In addition to an RF field, the ion guide may generate a quadrupole DC field. The DC field of the plates may be opposite in polarity to that of the ion guide.

Collection and separation systems, collection and separation methods, isotope analysis systems, methods of processing samples to analyze .sup.15N, .sup.13C, and .sup.34S, and the like are provided. A system that includes a collection system in gaseous communication with a first device, wherein the collection system is configured to isolate two or more gases of a gaseous sample and configured to introduce each to a second device independently of one another is provided.

An isotope ratio spectrometer is operated for measurement of a sample. First isotope ratios and first signal intensities are measured for a reference in the spectrometer, over a first measurement time period. A first relationship comprising a relationship between the first isotope ratios and the first signal intensities is determined. Sample isotope ratios and sample signal intensities are measured in the spectrometer, over a second measurement time period subsequent to the first measurement time period. Second isotope ratios and second signal intensities for a reference are measured in the spectrometer, over a third measurement time period subsequent to the second measurement time period. A second relationship comprising a relationship between the second isotope ratios and the second signal intensities is determined. A reference isotope ratio is estimated for a time X within the second measurement time period, based on the first relationship and the second relationship.

An isotope ratio spectrometer is operated for measurement of a sample. First isotope ratios and first signal intensities are measured for a reference in the spectrometer, over a first measurement time period. A first relationship comprising a relationship between the first isotope ratios and the first signal intensities is determined. Sample isotope ratios and sample signal intensities are measured in the spectrometer, over a second measurement time period subsequent to the first measurement time period. Second isotope ratios and second signal intensities for a reference are measured in the spectrometer, over a third measurement time period subsequent to the second measurement time period. A second relationship comprising a relationship between the second isotope ratios and the second signal intensities is determined. A reference isotope ratio is estimated for a time X within the second measurement time period, based on the first relationship and the second relationship.