A method of detecting Hg.sup.2+ ions in an aqueous solution is described. The method includes contacting the aqueous solution with a metal-organic framework (MOF) chemosensor composite to form a mixture and monitoring a change in an absorption and/or a fluorescence profile of the MOF chemosensor composite in the mixture to determine a presence or absence of Hg.sup.2+ ions in the aqueous solution. The MOF chemosensor composite includes fluorescein hydrazide (FH); and a MOF, including nickel as a metal ion and at least one trimesic acid (BTC) ligand. A hydrazide group on the fluorescein hydrazide coordinates to the metal ion of the MOF.

A peracetic acid decontamination chemical indicator including a substrate and an indicator composition disposed thereon, where the indicator composition comprises a colorant that changes color when exposed to a peracetic acid solution but does not change color when exposed to a hydrogen peroxide solution, an acidified hydrogen peroxide solution, or an acetic acid solution, and where the indicator composition does not include a transition metal salt or a halogen source, and methods of using the chemical indicator.

An optical sensor may include a housing, a printed circuit board, an optical emitter, and an optical detector. The housing can define a channel configured to receive a transparent tubing line through which fluid can flow during operation. The housing can have multiple optical pathways, including a primary optical pathway transecting the channel, a light emission optical pathway, and a light detection optical pathway. The optical emitter and optical detector can each be mounted on the printed circuit board. Further, the housing may be positioned on the printed circuit board with the optical emitter aligned to emit light into the light emission optical pathway and the optical detector aligned to receive light from the light detection optical pathway.

A reaction processor includes: a reaction processing vessel; a first optical head including a first objective lens OB1 for irradiating a sample with first excitation light and collecting first fluorescence generated from the sample; a second optical head including a second objective lens for irradiating a sample with second excitation light and collecting second fluorescence generated from the sample; and a holding member holding the first optical head and the second optical head. The wavelength range of the first fluorescence and the wavelength range of the second excitation light at least partially overlap with each other. A distance between the optical axis of the first objective lens and the optical axis of the second objective lens satisfies 2.Math.P.sub.0+2.Math.P.sub.1+4.Math.P.sub.2+4.Math.P.sub.3<P, P.sub.0=L.Math.NA/√(1−NA.sup.2), P.sub.1=t.sub.1.Math.NA/√(n.sub.1.sup.2−NA.sup.2), P.sub.2=t.sub.2.Math.NA/√(1−NA.sup.2), and P.sub.3=t.sub.3.Math.NA/√(n.sub.3.sup.2−NA.sup.2).

Techniques are disclosed relating to fluorescence-based flow cytometry. A flow cytometer may include a partially-reflective surface configured to reflect a first portion of fluorescent emissions from a sample to a first optical sensor and direct a second, greater portion of fluorescent emissions from the sample to a second optical sensor and a controller configured to determine a value representing the intensity of the fluorescent emissions based on a first measurement taken by the first optical sensor, a second measurement taken by the second optical sensor, or both. A flow cytometer may include a baseplate with a first side and a second, opposing side with a flow cell, a laser, and a reflective surface disposed above the first side and an optical sensor and isolating material disposed below the second side. The reflective surface receives fluorescent emissions and reflects at least a portion through the baseplate to the optical sensor. A flow cytometer may include a flow cell, a laser, a first optical sensor positioned to measure scattered laser light, a second optical sensor positioned to measure fluorescent emissions, and a controller configured to adjust the measurements taken by the second optical sensor based on a comparison of measurements taken by the first optical sensor with expected measurements based on a known beam profile of the laser beam.

A spectroscopic measurement device emits light to a measurement target and measures the measurement light output from the measurement target in accordance with the light emission. A spectroscopic measurement device includes: a first housing having a light shielding property and configured to house a light source that emits light and having a first opening through which the light emitted from the light source passes; a second housing having a light shielding property and having a second opening through which the measurement light passes and configured to house a spectrometer that receives the measurement light that has passed through the second opening; and an attachment configured to detachably hold the first housing and the second housing.

A dual function fluorometer-absorbance sensor features an absorbance-based sensor configured to receive one part of an optical signal transmitted through a body of water of interest along an optical beam transmission path, and determine absorbance-based sensor signaling containing information about an absorbance of the optical signal by one or more absorbance species of interest present in the body of water; and a fluorescence-based sensor configured to receive another part of the optical signal transmitted through the body of water of interest along a corresponding optical beam transmission path that is perpendicular to the optical beam transmission path, and determine fluorescence-based sensor signaling containing information about a fluorescence transmitted by one or more fluorophore species of interest present in the body of water.

Techniques are disclosed relating to fluorescence-based flow cytometry. A flow cytometer may include a partially-reflective surface configured to reflect a first portion of fluorescent emissions from a sample to a first optical sensor and direct a second, greater portion of fluorescent emissions from the sample to a second optical sensor and a controller configured to determine a value representing the intensity of the fluorescent emissions based on a first measurement taken by the first optical sensor, a second measurement taken by the second optical sensor, or both. A flow cytometer may include a baseplate with a first side and a second, opposing side with a flow cell, a laser, and a reflective surface disposed above the first side and an optical sensor and isolating material disposed below the second side. The reflective surface receives fluorescent emissions and reflects at least a portion through the baseplate to the optical sensor. A flow cytometer may include a flow cell, a laser, a first optical sensor positioned to measure scattered laser light, a second optical sensor positioned to measure fluorescent emissions, and a controller configured to adjust the measurements taken by the second optical sensor based on a comparison of measurements taken by the first optical sensor with expected measurements based on a known beam profile of the laser beam.

Provided herein is a method of effectively quantifying a target material by performing both colorimetry and fluorescence analysis on the same sample, based on metal nanoparticles and an aptamer.

A system and method for determining impurities in a beverage grade gas such as CO.sub.2 or N.sub.2 relies on a coupling of FTIR analysis and UV fluorescence detection. Conversion of reduced sulphur present in some impurities to SO.sub.2 can be conducted using a furnace. In some cases, CO.sub.2% also is determined.