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.

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.

An apparatus for in-line monitoring of nitrite content in a metalworking fluid is provided, the apparatus comprising a sample inlet for receiving a sample of a metalworking fluid, a dilution inlet for receiving a dilution fluid, a reagent inlet for receiving a photoactive reagent, a reaction volume for containing a sample mixture in fluid communication with the sample inlet, dilution inlet and reagent inlet, a photometer for monitoring the sample mixture, and a flow control system for controlling fluid flow in the apparatus, to: selectively introduce the sample, the dilution fluid and/or the photoactive reagent from the respective inlets to the reaction volume to form the sample mixture, retain the sample mixture in the reaction volume and discharge the sample mixture from the reaction volume.

A soil or plant analysis apparatus to perform low and high frequency measurements is described herein. In one embodiment, the soil analysis apparatus comprises a first sub-system to perform low frequency soil measurements and a second sub-system to perform high frequency soil measurements. The high frequency measurements of the second sub-system are at least 1.25 times the low frequency measurements of the first sub-system.

Thin films of organic semiconducting material comprising perylene diimide small molecules with pyrrolic N—H bonds. Films are prepared using green solvents including water and alcohols. The films can be solvent-resistant and generally range in thickness from 10 to 1000 nm. Perylene diimide molecules are dissolved in solvent by addition of a base to polarize the pyrrolic N—H bond believed to generate an ionic salt in alcohol or aqueous solution. Devices containing such films are provided. Methods of making films and methods of using films in OPV device applications and in amine sensors are provided.

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.

The invention provides an analytical process, which preferably is a one-step process, for detecting in a sample peroxide-based explosives, nitrate-based explosives and/or nitramine-based explosives, the process comprising contacting a sample suspected of containing a peroxide-based compound, especially a peroxide-based explosive, a nitramine, nitrate ester or a nitrate salt, especially a nitrate-based explosive and/or a nitramine-based explosive, with a composition comprising a Ni-porphyrin, an acid and preferably an acid-stable solvent.

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).

The present disclosure is directed to methods and systems for detecting a chemical substance. The methods and systems include mixing a sample of a substance of interest with an additive and then producing an adduct using an ionization source. The systems and methods further include performing a spectrometric analysis of the adduct and identifying the sample using comparative spectrometric data.

Reagents and methods are disclosed for detection of oxidizers and inorganic salts and other analytes of interest. The reagents can interact with their target analytes, especially oxidizer compositions or oxidizer-based explosives, to selectively enhance their ionization yield, interacting by chemical reaction or by forming an associative adduct which facilitates their detection. For example, the reagents can adduct with the counter-ion of the intended analyte for improved direct detection and/or react chemically via acid-base reactions to produce a new product for detection. In another aspect of the invention, reactive reagents and methods are also disclosed that facilitate indirect detection of the analyte at lower temperatures based on reduction-oxidation (redox) chemistry. These reagents are particularly useful in detecting oxidizer analytes.