A thermal simulation experiment method for hydrocarbon-water-rock interactions based on isotope tracing is disclosed. N-eicosane, water and feldspar grains are first heated and reacted in a high temperature high pressure (HTHP) reactor. The reactor is quenched in water to room temperature and samples from the reaction are tested to obtain the composition and content of gas products, the isotopic compositions of gas products, the water solutions and authigenic clays, the nuclear magnetic resonance (NMR) spectra of the liquid hydrocarbons and water solutions, and textures and compositions of minerals. The genetic mechanisms of mass exchange and occurrence of hydrocarbon-water-rock interactions are analyzed. A thermal simulation experiment method using multiple isotope tracing, calibrates the exchange processes and paths for H and O between the hydrocarbons, water and minerals to provide evidence for deciphering the mechanism of the organic-inorganic interactions is disclosed.

Disclosed is a method for pretreating Ranitidine hydrochloride sample, comprising steps: S1, weighing the Ranitidine hydrochloride sample containing an impurity of N-nitrosodimethylamine; S2, preparing a test solution of Ranitidine hydrochloride so that the concentration of N-nitrosodimethylamine in the test solution reaches the detection limit of high-performance liquid chromatography; S3, adding an alkaline solution to the Ranitidine hydrochloride test solution, wherein the alkaline solution reacts completely with hydrochloric acid in Ranitidine hydrochloride to give a Ranitidine neutralizing solution; S4, adding a silver ion solution to the Ranitidine neutralizing solution, and silver ions undergo a complete complexation reaction with secondary amino groups in Ranitidine to generate a precipitate. The precipitation of Ranitidine in the high-concentration Ranitidine test article is removed without producing NDMA as a by-product while retaining NDMA in the sample, greatly improving the sensitivity of NDMA detection and meeting the detection requirements of various types of mass spectrometry.

The present invention relates to the field of chemical analysis detection and application, in particular to a marker peptide of snake venom thrombin-like enzymes (SVTLEs) from Agkistrodon Halys Pallas and an application thereof. The amino acid sequence of the marker peptide of snake venom thrombin-like enzymes (SVTLEs) from Agkistrodon Halys Pallas is TLCAGVMEGGIDTCNR. Characterizing the source of species and a content of the SVTLEs in a to-be-detected sample by using the marker peptide includes the following steps of: pretreating the to-be-detected sample by trypsin through enzymolysis, and taking a supernatant of an enzymolysis liquid as a test solution; and injecting the test solution and a reference solution into a liquid chromatography-mass spectrometer, and selecting a qualitative ion pair and a quantitative ion pair for detecting the source of species and a content of the SVTLEs in the to-be-detected sample.

The present disclosure relates to a method for using chemical tags which have two or more sites for ionization to improve quantification and identification of components of interest from a complex mixture. This method relies on first selectively reacting one or more component in a sample with a chemical tag having two or more sites for ionization, followed by separation of components based on charge status, and finally characterization of each component to identify the same. Additionally disclosed are compounds useful as chemical tags in the disclosed methods.

The disclosure describes a method for simultaneous determination of nitrogen and oxygen isotope compositions of natural nitrate and nitrite, which quantitatively converts natural nitrate and nitrite into an organic ester and a nitro-compounds respectively, and then nitrate and nitrite δ.sup.18O and δ.sup.15N are simultaneously determined by adopting a gas chromatography/pyrolysis/gas chromatography/isotope ratio mass spectrometry coupling technology (GC/Py/GC/IRMS). According to the method for simultaneously determining the nitrogen and oxygen isotope compositions of the natural nitrate salt and nitrite salt, the small amount of sample does not result in the loss, acquisition, exchange and fractionation of nitrogen and oxygen.

A method for preparing an analysis sample includes providing a sample containing a glycan, and performing an amidation reaction through contacting the sample with an amidation reaction solution having a pH of 7.7 or more, the amidation reaction solution containing at least one first compound which is to be reacted with a lactone included in the glycan, and which is selected from the group consisting of ammonia to be reacted with a lactone included in the glycan, primary amines having one or no carbon atom directly linked to a carbon atom linked to an amino group, hydrazine, hydrazine derivatives, hydroxylamine, and salts thereof, and alkalinizing agents to amidate the lactone, wherein when the alkalinizing agent is an amine, the alkalinizing agent is at least one amine selected from the group consisting of branched primary amines in which two or more carbon atoms are directly linked to a carbon atom linked to an amino group, secondary amines, and tertiary amines.

A method for simultaneously determining fat-soluble vitamins and carotenoids in serum, and belonging to the technical field of analytical chemistry, includes an ionic liquid (IL) or a binary mixed solvent composed of an IL and another solvent is adopted as an extractant; the biological samples are pre-treated by liquid-liquid extraction (LLE) and then detected by high-performance liquid chromatography (HPLC); retinyl acetate and trans-β-apo-8′-carotenal are adopted as the internal standards for fat-soluble vitamins and carotenoids, respectively; and the internal standard method is adopted to establish standard curves for quantification based on the retention time and the UV-Vis absorption spectrum. Compared with the existing methods, in the disclosure, the pretreatment process is simple and easy to be conducted, the sample can be prepared in a short time, and the toxic and harmful organic solvent is used at a reduced amount.

A method of analyzing phenylhydrazine content in a 3-methyl-1-phenyl-2-pyrazolin-5-one active pharmaceutical ingredient includes obtaining a first measured value by measuring a phenylhydrazine content of a standard solution including phenylhydrazine or a salt thereof, a first acidic water and a first water-soluble organic solvent and having a phenylhydrazine concentration of 0.01 μg/mL to 10 μg/mL, obtaining a second measured value by measuring a phenylhydrazine content in a sample solution including a 3-methyl-1-phenyl-2-pyrazolin-5-one active pharmaceutical ingredient, a second acidic water and a second water-soluble organic solvent, and detecting a phenylhydrazine content in a 3-methyl-1-phenyl-2-pyrazolin-5-one active pharmaceutical ingredient based on the first measured value and second measured value. The first acidic water is hydrochloric acid, and/or an aqueous acetic acid solution, the first water-soluble organic solvent is acetonitrile and/or methanol, the second acidic water is hydrochloric acid, and/or an aqueous acetic acid solution, and the second water-soluble organic solvent is acetonitrile and/or methanol.

Provided are a method, an apparatus, and a kit for detecting a neuroblastoma in a subject and/or for monitoring a therapeutic effect on the neuroblastoma, by measuring a urinary tumor marker(s) in a sample from the subject.

Described herein are the amphetamine-related compounds amphetamine carbamate (amphetammonium-amphetacarbamate) and amphetacarbamate, methods of making them, methods for detecting or quantitatively determining the amount of amphetacarbamate or amphetamine carbamate in a compositions, and ion chromatography columns useful in such methods.