A rapid flow-through, highly sensitive microfluidic photoionization detector (PID) which is micro-fabricated directly onto a substrate, such as a conductive silicon wafer, is provided. The microfluidic PID has an ionization chamber volume of less than 9 L. The microfluidic PID may have a flow through design with a microfluidic channel defines a serpentine pattern on the substrate. The flow through design of the microfluidic PID results in negligible dead volume, thus allowing a shortened response time over existing commercially available designs. Such microfluidic PIDs are particularly useful with gas chromatography (GC), including microGC and multi-dimensional microGC systems. Methods for calibrating PIDs are also provided.

A rapid flow-through, highly sensitive microfluidic photoionization detector (PID) which is micro-fabricated directly onto a substrate, such as a conductive silicon wafer, is provided. The microfluidic PID has an ionization chamber volume of less than 9 L. The microfluidic PID may have a flow through design with a microfluidic channel defines a serpentine pattern on the substrate. The flow through design of the microfluidic PID results in negligible dead volume, thus allowing a shortened response time over existing commercially available designs. Such microfluidic PIDs are particularly useful with gas chromatography (GC), including microGC and multi-dimensional microGC systems. Methods for calibrating PIDs are also provided.

The present disclosure relates to an ion exchange process, as well as a process and system for detecting nitrates, which employ a class of dopants comprising at least two functional groups capable of simultaneous convergent hydrogen bonding with a nitrate ion. In an aspect, the present disclosure provides an ion exchange process for forming a negatively charged nitrate-dopant ion analyte for analysis by a spectrometry analysis instrument, comprising: providing a gas comprising a dopant in both neutral and ionized forms; contacting a nitrate-containing sample with the gas comprising the dopant and thereby desorbing a nitrate ion from the sample to form a negatively charged nitrate-dopant ion analyte and replacing the desorbed nitrate ion with a negatively charged ionized dopant molecule; wherein the dopant is an organic compound comprising two or more carbon atoms and two or more functional groups capable of simultaneous convergent hydrogen bonding with a nitrate ion; or the dopant is an organic compound comprising at least two carbon atoms and only a single functional group capable of hydrogen bonding with a nitrate ion, which group is a COOH functional group, and where the carbon atom of the COOH functional group is bonded directly to another carbonyl group; and with the proviso that the dopant is not lactic acid, a lactic acid salt or a compound that forms lactate ions upon ionization.

The present disclosure relates to an ion exchange process, as well as a process and system for detecting nitrates, which employ a class of dopants comprising at least two functional groups capable of simultaneous convergent hydrogen bonding with a nitrate ion. In an aspect, the present disclosure provides an ion exchange process for forming a negatively charged nitrate-dopant ion analyte for analysis by a spectrometry analysis instrument, comprising: providing a gas comprising a dopant in both neutral and ionized forms; contacting a nitrate-containing sample with the gas comprising the dopant and thereby desorbing a nitrate ion from the sample to form a negatively charged nitrate-dopant ion analyte and replacing the desorbed nitrate ion with a negatively charged ionized dopant molecule; wherein the dopant is an organic compound comprising two or more carbon atoms and two or more functional groups capable of simultaneous convergent hydrogen bonding with a nitrate ion; or the dopant is an organic compound comprising at least two carbon atoms and only a single functional group capable of hydrogen bonding with a nitrate ion, which group is a COOH functional group, and where the carbon atom of the COOH functional group is bonded directly to another carbonyl group; and with the proviso that the dopant is not lactic acid, a lactic acid salt or a compound that forms lactate ions upon ionization.

An ion mobility gas detector apparatus including a detector core, an inlet gas path, an exhaust gas path, a source of diluent gas, and at least one or more sensors for measuring temperature, pressure and humidity of gas streams. Further included is a mixing mechanism adapted to mix at least first and second gas streams in response to one or more sensor measurements. A controller is provided for applying drive signals to the detector core.

An ion mobility gas detector apparatus including a detector core, an inlet gas path, an exhaust gas path, a source of diluent gas, and at least one or more sensors for measuring temperature, pressure and humidity of gas streams. Further included is a mixing mechanism adapted to mix at least first and second gas streams in response to one or more sensor measurements. A controller is provided for applying drive signals to the detector core.

A particulate measurement apparatus comprises a control section, which provisionally determines in an anomaly determination process that a corona core wire is in a short anomaly state when a linear voltage is equal to or lower than a particular voltage value and increments a sensor anomaly counter CNS or a chassis anomaly counter. The control section determines that the corona core wire is in a short anomaly state when the count value of one of the anomaly counters is equal to or greater than a determination threshold.

A particulate measurement apparatus comprises a control section, which provisionally determines in an anomaly determination process that a corona core wire is in a short anomaly state when a linear voltage is equal to or lower than a particular voltage value and increments a sensor anomaly counter CNS or a chassis anomaly counter. The control section determines that the corona core wire is in a short anomaly state when the count value of one of the anomaly counters is equal to or greater than a determination threshold.

In a particulate measurement apparatus (300) of a particulate measurement system (10), a control section (600) provisionally determines in an anomaly determination process at S130 that a corona core wire (202) is in a wire-breakage anomaly state; namely, that the corona core wire (202) is broken, when a corona low-side current C1 is equal to or smaller than a current determination value C1min, and increments a wire-breakage anomaly counter CNB at S140. The control section (600) determines that the corona core wire (202) is in the wire-breakage anomaly state at S170 when the count value of the wire-breakage anomaly counter CNB is equal to or greater than a wire-breakage determination threshold Cth; namely, that the result of the determination at S160 is Yes.

A dielectric barrier discharge ionization detector Includes: a dielectric tube; a high-voltage electrode connected to an AC power source and circumferentially formed on the outer wall of the dielectric tube; upstream-side and downstream-side ground electrodes and circumferentially formed above and below the high-voltage electrode; a discharging section for generating electric discharge to create plasma, from a gas containing argon; and a charge-collecting section for ionizing sample-gas components by the plasma and detecting an ion current formed by the ionized components. The detector also satisfies one or both of the following conditions: the upstream-side ground electrode is longer than a creeping discharge initiation distance between a tube-line tip member at the upper end of the dielectric tube and the high-voltage electrode; or the downstream-side ground electrode is longer than a creeping discharge initiation distance between the high-voltage electrode and the charge-collecting section.