Methods of quantifying N.sup.2-carboxyethyl-2′-deoxyguanosine (CEdG) levels in biological samples and comparing those levels to known normal levels can diagnose a number of disorders, including diabetes and cancer. Methods can also determine whether therapies for disorders are effective by measuring CEdG levels before and after treatment. Measurement of CEdG levels occurs using liquid chromatography electrospray ionization tandem mass spectrometry.

Method for calibrating a gas chromatograph to render the calibration of the gas chromatograph more error-proof, wherein relative response factors determined during the calibration are compared with universal relative response factors contained in the memory and typical of the detectors, where an error message is generated and output if the relative response factors determined in the calibration deviate beyond a predetermined degree from the universal relative response factors, and where the universal relative response factors are determined and provided for different components by the manufacturer of the detectors, for instance.

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 for determining in a sample, by mass spectrometry, the amount of one or more analytes selected from the group consisting of 12,13-DiHOME, 3-hydroxybutyrate (BHBA), 3-hydroxyoctanoate, 3-methylglutarylcarnitine, 3-ureidopropionate, 7-alpha-hydroxy-4-cholesten-3-one (7-Hoca), citrate, fucose, fumarate, gamma-tocopherol, glutamate, glutarate, glycerol, glycochenodeoxycholate, glycocholate, hypoxanthine, maleate, malonate, mannose, orotate, 2,3-pyrdinedicarboxylate, ribose, serine, taurine, taurochenodeoxycholate, taurocholate, palmitoleate, linolenate, xanthine, xylitol, and combinations thereof is described. The method comprises subjecting the sample to an ionization source under conditions suitable to produce one or more ions detectable by mass spectrometry from each of the one or more analytes; measuring, by mass spectrometry, the amount of the one or more ions from each of the one or more analytes; and using the measured amount to determine the amount of each of the one or more analytes in the sample.

An automated method of monitoring a state of an analyzer is provided including a mass spectrometer (MS) with an electrospray ionization (ESI) source coupled to a liquid chromatography (LC) stream, including monitoring an electrospray ionization current of the ESI source and identifying a condition of multiple conditions of the analyzer based on the monitored ionization current of the ESI source, one of the conditions being a presence of a dead volume in a liquid chromatography stream of the analyzer downstream of an LC column of the LC stream.

This invention employs columns and methods to apply external and internal standards and compounds. Analytical standard or compounds are adsorbed to a solid phase extraction media and are stored indefinitely. The standards or compounds remain stable on the solid phase extraction media without decomposing. The standards or compounds may be removed from the solid phase extraction media with a solvent.

A method for preparation of a dried blood sample for multiplexing of analytes includes the steps of mixing an Internal Standard solution with a first diluent in a vessel, the Internal Standard solution including a plurality of different Internal Standards, adding the dried blood sample to the vessel, sonicating the vessel containing the Internal Standard solution, the first diluent and the dried blood sample, and removing the dried blood sample from the vessel. The Internal Standard solution can include a plurality of Internal Standards. The Internal Standard solution can include at least 15 Internal Standards. The dried blood sample can be generated using less than 50 L of blood. The dried blood sample can be generated using less than 10 L of blood. The first diluent can include methanol or a mixture of water and methanol.

Provided are methods for detecting or determining the amount of guanidinoacetate (GAA), creatine, and creatinine by mass spectrometry.

The present invention pertains to a fruit juice composition wherein the content of an aroma component is reduced but the content of a nutritional functional component and the content of a saccharide are not substantially reduced, a method for producing the composition, and a food or beverage containing the composition.

The present invention relates to a plastic reference material and a method of manufacturing the same, wherein the concentration of at least one chemical substance is characterized from a signal intensity of the chemical substance and a signal intensity of the isotope-labeled chemical substance of the chemical substance obtained using the pyrolysis GC-MS instrument by weighing a mass of a candidate material for the plastic reference material using a balance, weighing an isotope-labeled chemical substance of the chemical substance using a balance, preparing a mixed solution by dissolving the weighed candidate material for the plastic reference material and the weighed isotope-labeled chemical substance in a solvent, introducing a product resulting from evaporation of the solvent from the mixed solution into a pyrolysis GC-MS instrument, and calculating the concentration of the chemical substance included in the candidate material for the plastic reference material.