Methods, apparatuses, and systems for diagnosing misalignment in gas detecting devices are provided. An example method may include causing at least one detector component of a receiver element of the open path gas detecting device to generate a first light intensity indication corresponding to first infrared light; causing the at least one detector component to generate a second light intensity indication corresponding to second infrared light; and generating an alignment indication based at least in part on the first light intensity indication and the second light intensity indication.

Methods, apparatuses, and systems for diagnosing misalignment in gas detecting devices are provided. An example method may include causing at least one detector component of a receiver element of the open path gas detecting device to generate a first light intensity indication corresponding to first infrared light; causing the at least one detector component to generate a second light intensity indication corresponding to second infrared light; and generating an alignment indication based at least in part on the first light intensity indication and the second light intensity indication.

A method of measuring a concentration of NO.sub.2 in a gaseous mixture using a multimode laser beam that covers a tunable spectral range with a width of no more than 5 nm, wherein the multimode laser beam provides a high resolution transmittance spectrum at an absorption cross section of NO.sub.2 molecules, and a system for measuring the concentration of NO.sub.2 in the gaseous mixture. Various combinations of embodiments of the system and the method are provided.

A method of measuring a concentration of NO.sub.2 in a gaseous mixture using a multimode laser beam that covers a tunable spectral range with a width of no more than 5 nm, wherein the multimode laser beam provides a high resolution transmittance spectrum at an absorption cross section of NO.sub.2 molecules, and a system for measuring the concentration of NO.sub.2 in the gaseous mixture. Various combinations of embodiments of the system and the method are provided.

The instant disclosure provides a gas concentration detection device including a plurality of gas concentration measurement modules and a control module. The control module coupled with the plurality of gas concentration measurement modules. Each gas concentration measurement module including: a gas chamber, a signal generating unit and a sensing unit. The control module providing a plurality of clock signals, wherein each clock signal controls the corresponding signal generating unit to correspondingly generate the medium to enter the gas chamber and pass through the gas. The sensing unit outputs a sensing signal by receiving the medium, and the control module corrects the sensing signals from the sensing units to respectively obtain corrected sensing signals, and the corrected sensing signals are integrated by the control module to obtain a gas concentration signal.

The instant disclosure provides a gas concentration detection device including a plurality of gas concentration measurement modules and a control module. The control module coupled with the plurality of gas concentration measurement modules. Each gas concentration measurement module including: a gas chamber, a signal generating unit and a sensing unit. The control module providing a plurality of clock signals, wherein each clock signal controls the corresponding signal generating unit to correspondingly generate the medium to enter the gas chamber and pass through the gas. The sensing unit outputs a sensing signal by receiving the medium, and the control module corrects the sensing signals from the sensing units to respectively obtain corrected sensing signals, and the corrected sensing signals are integrated by the control module to obtain a gas concentration signal.

A system includes a sensor body that has a folded optical waveguide configured in a “U” shape, wherein the waveguide is configured to convey infrared energy from one end of the waveguide to the other end of the waveguide.

A method for determining the total organic carbon in a sample which includes mixing the sample with a reagent containing at least one acid effective for reacting with inorganic carbon-containing materials in the sample, and at least one oxidizing agent effective for oxidizing organic carbon-containing materials in the sample in the presence of ultraviolet radiation, and detecting the carbon dioxide generated, is described. The at least one acid may include phosphoric acid, while the oxidizing agent may include sodium persulfate. In accordance with an embodiment of the inventive concept, the sample is first injected into a reaction chamber, which is continuously flushed with carbon dioxide free gas with no UV light present, and CO.sub.2 generated from any inorganic carbon in the sample as carbonates is flowed through the detector, and may be recorded. Subsequent to this step, the UV light is passed through the reaction chamber and CO.sub.2 generated from the reaction of the at least one oxidizing agent with the organic material in the solution in the presence of ultraviolet radiation, is flowed through the detector, which may be a non-dispersive infrared detector, after the reaction chamber is sparged using a carbon dioxide free gas, and recorded.

For determining concentration of a targeted molecule M in a liquid sample admixed with interfering molecules M.sub.J which overlap its absorption band, a NDIR reflection sampling technique is used. Besides the signal source, a reference and an interference source are added. M is calculated by electronics which use R.sub.ave(t) from a pulsed signal and reference channel output and a calibration curve which is validated by use of R.sub.Java(t.sub.2) from a pulsed interference and reference channel output. Signal, interference and reference sources are pulsed at a frequency which is sufficiently fast so that a given molecule of M or M.sub.J will not pass in and out of the liquid sampling matrix within the pulsing frequency.

The light projection assemblies and opacity monitors described in this specification have an integrating sphere with an input aperture, an output aperture, and a spherical-shaped internal chamber. An LED source is located external to the chamber at the input aperture. A light baffle is located within the chamber at the output aperture. A condenser lens is located external to the chamber at the output aperture.