A di(2-ethylhexyl) terephthalate composition is provided. The di(2-ethylhexyl) terephthalate composition comprises di(2-ethylhexyl)terephthalate, at least one of a first component, a second component and a third component, and a fourth component When the di(2-ethylhexyl) terephthalate composition is characterized by gas chromatography (GC), the first component is eluted at a retention time ranging from 4.8 minutes to 6.0 minutes, the second component is eluted at a retention time ranging from 9.0 minutes to 10.0 minutes, the third component is eluted at a retention time ranging from 10.1 minutes to 12.0 minutes, and the fourth component is eluted at a retention time ranging from 21.0 minutes to 22.1 minutes. The ratio of the total area of the chromatographic peaks indicating the first component, second component, and third component to the area of the chromatographic peaks indicating the fourth component is 0.135 to 1.720.

Disclosed herein is a method for selectively reducing, using electrical energy, CO.sub.2 to carbon monoxide or formic acid, a catalyst for use in the method, and an electrochemical reduction system. The method for producing carbon monoxide or formic acid by electrochemically reducing carbon dioxide of the present invention includes (a) reacting carbon dioxide with a metal complex represented by formula (1), and (b) applying a voltage to a reaction product of the carbon dioxide and the metal complex represented by formula (1):

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In an LC system using an ODS column (15) and UV detector (17), a cannabis-derived sample is analyzed by gradient elution using a phosphoric acid aqueous solution and phosphoric-acid-containing methanol. A control unit (3) regulates the openings of solenoid valves in a mixer (12) so that the increase rate of the mixture ratio of the phosphoric-acid-containing methanol in a second part of the analysis period is higher than in a first part. By this operation, ten active ingredients (including Total THC, Total CBD and CBN) contained in cannabis can be satisfactorily separated within an analysis time which is equal to or even shorter than approximately 30 minutes. Each ingredient separated by the column (15) is detected by the UV detector (17). An active ingredient identification processor (22) identifies the ten active ingredients based on the retention times of the peaks on a chromatogram created from the detection signals.

Disclosed is an organic carbon detector that can be used with a liquid chromatography equipment such as a size exclusion chromatography. The organic carbon detector contains a carbon oxidization subsystem and a stripping and CO.sub.2 detection subsystem arranged and detachably connected with each other in said order. The carbon oxidization subsystem contains a microfluidic agent injection module (1), an inorganic carbon removal module (2), a microfluidic ultraviolet oxidation module (3) and a vacuum pumping system (4), configured to remove inorganic carbons and oxidize organic carbons. The stripping and CO.sub.2 detection subsystem contains a stripping module (7) and a CO.sub.2 detector (12), using a carrier gas to transfer the organic carbon converted gas to the CO.sub.2 detector (12). Also disclosed is a method of using the organic carbon detector in water quality monitoring.

The present invention provides a related substance of (3S)-3-(4-(3-(1,4-dioxaspiro[4,5]dec-7-en-8-yl)benzyloxy)phenyl)hex-4-inoic acid, and a method for evaluating the quality of (3S)-3-(4-(3-(1,4-dioxaspiro[4,5]dec-7-en yl)benzyloxy)phenyl)hex-4-inoic acid using the same. According to the present invention, it is possible to evaluate the quality, stability and the like of a pharmaceutical composition comprising (3S)-3-(4-(3-(1,4-dioxaspiro[4,5]dec-7-en-8-yl)benzyloxy)phenyl)hex-4-inoic acid using a compound of Chemical Formula 2 or a salt thereof as a reference standard.

Example aspects of a volatile organic compound detection device, a wearable health monitoring device, and a method of monitoring a user's health are disclosed. The volatile organic compound detection device can comprise a collector comprising a collector material configured to collect volatile organic compounds given off from a user's skin; a separator comprising a gas chromatography column configured to separate mixtures of the volatile organic compounds into their constituent chemicals; and an identifier comprising a detector and a processor, the detector configured to transduce the constituent chemicals into a signal, the processor configured to process the signal to identify specific volatile organic compounds indicative of a health condition.

Disclosed herein are a group of gastric cancer VOC markers in saliva and an application thereof in the preparation of a diagnostic reagent of gastric cancer. The markers are a combination of compounds selected from the group consisting of acetaldehyde, 2-methylbutyraldehyde, isopropanol, hexanal, n-butanol, cineole, nonanal, menthone, 2-ethylhexanol, menthol, anethole and dodecanol. The diagnostic reagent is used for detecting the contents of the marker in a saliva sample of a subject to perform the diagnosis of gastric cancer.

The measurement of glutaraldehyde-based biocides in seawater without the use of a derivatization agent. The measurement of glutaraldehyde-based biocides in seawater may be performed without additional components to reduce background interferences. The concentration of a glutaraldehyde-based biocides in a seawater sample is determined using reversed phase liquid chromatography and a gradient mobile phase of acetonitrile and deionized water. Systems for determining the concentration of glutaraldehyde-based biocide in a seawater injection system are also provided.

Disclosed is a detection method for N-nitrosodimethylamine (NDMA) impurities, comprising: (1) obtaining a test solution containing a sample to be tested; and (2) detecting the test solution by means of gas chromatography-mass spectrometry to determine the content of an N-nitrosodimethylamine impurity in the sample. The method provided in the present invention has a good separating effect, a wide linear range, a high sensitivity and a good method durability, and can detect the content of N-nitrosodimethylamine (NDMA) in the sample rapidly and effectively.

The invention relates to a system and micro monitor apparatus, a space-, time-, and cost-efficient device to concentrate, identify, and quantify organic compounds in gas environments. The invention further relates to a method centered on gas chromatography for identifying and quantifying organic compounds in gas environments, using air as the carrier gas, without the need for a compressed pre-bottled purified carrier gas.