A molecular probe for selective detection of a nitrate and/or a decomposition product of a nitrate by generating a fluorescence signal in response to an excitation in the wavelength range between 340-370 and 480-520 nm, wherein the molecular probe is selected from a triarylborane dye according to formula (7) and a BODIPY dye according to formula (13):

##STR00001##

A rapid test device includes a micropad chip configured for a multi-parameter chemical testing of an input sample. A plurality of paper layers of the micropad chip are in fluid communication, including a sample absorption element, a filtering element configured to filter the input sample, and a sample distribution element configured to distribute the input sample received from the filtering element to a remainder of the plurality of paper layers. One or more reacting elements associated with the multi-parameter chemical testing of the input sample have one or more colorimetric reagents in fluid communication with the sample distribution element. A colorimetric result displaying element in fluid communication with the one or more reacting elements is configured to display a colorimetric result of the testing of the input sample with the at least one reacting element for a respective chemical test of the multi-parameter chemical testing.

An embodiment provides a method for measuring nitrate in an aqueous sample, including: introducing an aqueous sample containing an amount of nitrate to a cation exchange resin; flowing the aqueous sample over copper metal; adding a reducing reagent to the aqueous sample; adding a colorimetric indicator to the aqueous sample; and measuring the amount of nitrate in the aqueous sample by measuring a change in intensity of the absorbance. Other aspects are described and claimed.

In various embodiments the present invention is directed to a complex for use in detecting nitrite, a method for making the complex, and a method for detecting nitrite with the complex. The complex comprises a structure of Formula (I) ##STR00001## where R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are independently selected from hydrogen, a halogen atom, a C1-C4 straight or branched alkyl group, a C1-C4 straight or branched alkoxyl group, a phenyl group or a heterocyclic group, or any two of R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 together form a phenyl group and the others are independently selected from hydrogen, a halogen atom, a C1-C4 straight or branched alkyl group, a C1-C4 straight or branched alkoxyl group, or a hydroxyl group, where said phenyl group is optionally substituted with a C1-C4 alkyl group or a halogen atom; and wherein n is an integer selected from 0, 1 or 2.

An explosive detection system may include a suction nozzle having a suction port for introducing air containing explosive particles at one end thereof, a discharge nozzle having a discharge port for discharging air at one end thereof, a sensing block in which a detection material capable of detecting explosive particles in the air is disposed, a sensor unit for emitting light to the sensing block and outputting a sensing signal, a first guide pipe connected to the other end of the suction nozzle and guiding the air introduced through the suction nozzle to the sensing block in which the detection material is disposed, a suction force generating unit formed at the other end of the discharge nozzle and to suck air through the suction port and to provide a suction force for sucking air into the sensing block and discharging the air to a discharge port formed at one end of the discharge nozzle, a second guide pipe formed between the sensing block and the suction force generating unit and discharging the air introduced into the sensing block by the suction force generated by the suction force generating unit to the discharge port of the discharge nozzle, and a controller for determining whether explosive particles are present in the air using the sensing signal.

The invention provides a mild procedure for the functionalization of cellulose and other substrates with a detection reagent such as N-(1-naphthyl)ethylenediamine and is able to achieve much higher functionalization density than previously reported. A paper-based device created using cellulose functionalized according to the invention allowed for much lower detection limits for nitrite in various kinds of water samples than have been seen using paper-based devices. In addition, grafting of N-(1-naphthyl)ethylenediamine to cellulose improved the stability of the N-(1-naphthyl)ethylenediamine in the presence of moisture and light.

The present invention provides, inter alia, a device comprising a colorimetric detection layer configured to undergo a color change upon interaction with a first analyte of interest. The detection layer comprises a first plurality of self-assembled fiber bundles. At least a fraction of the fiber bundles undergo a change from a first conformation to a second conformation upon interaction with the first analyte of interest, thereby undergoing a color change. The invention also provides a method for using the system to detect an analyte of interest.

A wipe for detecting the presence of an explosive substance is composed of an absorbent or adsorbent substrate and a chemical detection solution impregnated within the substrate. In one embodiment the chemical detection solution includes a combination of reagents operable, when contacted with a particular explosive substance to undergo a chemical reaction or a series of chemical reactions to produce a compound having a visible color. In another embodiment, the chemical detection solution includes a redox color indicating agent that is operable to exhibit a color change upon reacting with the explosive substance.

An in-situ analyzer for a nutritive salt includes an injector, a calorimetric detector (11), a mixing ring (12), a sample pipeline, a pure water bin, a standard solution bin and various reagent bins of the analyzer which are correspondingly connected to ports of a multi-way valve (5). A microprocessor is connected to a first motor driver and a first motor in turn, and then connected to an injection pump (6) of the injector. The microprocessor is connected to a second motor driver and a second motor in turn, and then connected to the multi-way valve (5) for controlling one port in the multi-way valve connected to the injector to be in respective and corresponding communication with other ports in the multi-way valve (5). The colorimetric detector (11) is connected with the microprocessor.

The patent relates to para amino benzoic acid (pABA) sensitized terbium (Tb.sup.3+) doped spherical LaF.sub.3 nanoparticles used for detection of nitro group containing compounds using the terbium (Tb.sup.3+) doped spherical LaF.sub.3 nanoparticles sensitized by para amino benzoic acid (pABA).