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.

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.

An ion generator may be configured to generate ions within a fluid passage that is at least partly defined by an electrical insulator, where the ion generator may include: a discharge electrode placed within the fluid passage; a ground electrode placed in a vicinity of the discharge electrode; and a power source configured to intermittently apply a predetermined discharge voltage to the discharge electrode with respect to the ground electrode. The power source may be configured to apply a base voltage to the discharge electrode with respect to the ground electrode during at least part of a time period after applying the discharge voltage, the base voltage having an opposite polarity to the discharge voltage.

An ion generator may be configured to generate ions within a fluid passage that is at least partly defined by an electrical insulator, where the ion generator may include: a discharge electrode placed within the fluid passage; a ground electrode placed in a vicinity of the discharge electrode; and a power source configured to intermittently apply a predetermined discharge voltage to the discharge electrode with respect to the ground electrode. The power source may be configured to apply a base voltage to the discharge electrode with respect to the ground electrode during at least part of a time period after applying the discharge voltage, the base voltage having an opposite polarity to the discharge voltage.

A light source emits excitation light to discharge gas that flows through a dielectric tube. A ground electrode unit includes a first ground electrode and a second ground electrode arranged at a distance from each other in an axial direction of the dielectric tube. A high-voltage electrode is provided between the first ground electrode and the second ground electrode. A first distance between the first ground electrode and the high-voltage electrode is shorter than a second distance between the second ground electrode and the high-voltage electrode. A cover is provided on an outer wall of the dielectric tube at a position between the first ground electrode and the high-voltage electrode. The light source is arranged to emit excitation light such that an optical axis thereof is directed toward a position where the cover is not provided on the outer wall of the dielectric tube.

Particulate measurement processing executed by a sensor control section of a particulate measurement system includes a step of stopping voltage conversion by a first isolation transformer and a second isolation transformer, a step of obtaining correction information B, and a step of correcting ion current A through use of the correction information B. The correction information B reflects improper current generated through particulates, etc. (soot or the like) adhering to a particulate sensor. The ion current A (signal current I.sub.esc) is corrected through use of the correction information B, and the amount of soot S is computed through use of the corrected ion current A. As a result, it is possible to measure the amount of the soot S (the amount of particulates) while suppressing the influence of the improper current.

Particulate measurement processing executed by a sensor control section of a particulate measurement system includes a step of stopping voltage conversion by a first isolation transformer and a second isolation transformer, a step of obtaining correction information B, and a step of correcting ion current A through use of the correction information B. The correction information B reflects improper current generated through particulates, etc. (soot or the like) adhering to a particulate sensor. The ion current A (signal current I.sub.esc) is corrected through use of the correction information B, and the amount of soot S is computed through use of the corrected ion current A. As a result, it is possible to measure the amount of the soot S (the amount of particulates) while suppressing the influence of the improper current.

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.