A system capable of performing both single and multidimensional liquid chromatography includes a solvent delivery system, a sample injection system, a first dimension column path configured to perform a separation process in a first dimension, a second dimension column path configured to perform a separation process in a second dimension that is different than the first dimension, a valve system; and a sample injection system fluidically connected to the valve system. The valve system is configured to direct flow from a sample injection system to a first dimension column path when the valve system is in a first position, and to direct flow from the sample injection system to the second dimension column path without the flow path flowing through the first dimension column path in the chromatography system when the valve system is in a second position.

The present application is related to a method for identifying whether porcine heparin is adulterated with heparin from ruminants, comprising: (1) respectively detecting the contents of trisaccharide(4S) and ΔUA2S-GlcNAc6S (ΔIA) in a sample and at least three batches of porcine heparin standards; (2) calculating a ratio of the trisaccharide(4S) to the ΔIA as well as a standard deviation (SD) of the ratio in the porcine heparin standards; when the ratio of the trisaccharide(4S) to the ΔIA in the sample exceeds a maximum value of the ratio in the porcine heparin standards+3SD, where the sample is considered to be mixed or adulterated with heparin from ruminants; wherein the detection method used is hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) or multiple reaction monitoring (MRM). The method can distinguish porcine heparin from ovine and bovine heparin based on the structural differences, regardless of the production process the heparin has undergone.

Disclosed are a tea type differentiation method and system, belonging to the technical field of detection. The method comprises: building a differentiation function by using ionic strengths of 20 compounds as evaluation indexes to discriminate tea types. According to the disclosure, the tea types are discriminated by using relative abundance of 20 compounds in tea, problems in sensory differentiation can be solved, the tea is classified more objectively and scientifically, and the reliability and accuracy of differentiation results are improved. By using three algorithms, the feasibility and accuracy of using 20 discovered compounds for tea type differentiation in a combined manner are validated.

A method of performing targeted multiplexed mass spectrometry includes performing, at a mass spectrometer, a targeted MS3 analysis of an isobaric tag-labeled target analyte included in a multiplex sample eluting from a column. The targeted MS3 analysis is performed during an acquisition segment scheduled based on an expected retention time of the isobaric tag-labeled target analyte. The method further includes performing, during the acquisition segment, a plurality of MS2 analyses of product ions derived from components included in the multiplex sample and eluting from the column. The method further includes determining, based on MS3 mass spectra acquired by the targeted MS3 analysis and MS2 mass spectra acquired by the plurality of MS2 analyses, a relative quantity of the isobaric tag-labeled target analyte in the multiplex sample.

A method for determining in a sample, by mass spectrometry, the amount of one or more analytes selected from the group consisting of N-acetylthreonine, TMAP, phenylacetylglutamine, tryptophan, creatinine, meso-erythritol, arabitol, myo-inositol, N-acetyl serine, N-acetylalanine, 3-methylhistidine, trans-4-hydroxyproline, kynurenine, urea, C-glycosyltryptophan, 3-indoxyl sulfate, pseudouridine, 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 of the 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 of the one or more ions to determine the amount of each of the one or more analytes in the sample. Also described is a kit comprising one or more isotopically labeled analogues as internal standards for each of the one or more analytes.

The present invention provides a method in which a porous body having a monoclonal antibody to be measured immobilized in pores thereof is brought into contact with nanoparticles having a protease immobilized thereonto in a liquid to perform selective protease digestion of the monoclonal antibody and a peptide fragment obtained by the digestion is detected by liquid chromatography mass spectrometry (LC-MS), wherein the monoclonal antibody is digested with the protease in the presence of an antibody specifically binding to the monoclonal antibody or a target molecule of the monoclonal antibody.

The invention relates to the detection of non-metabolized vitamin D. In a particular aspect, the invention relates to methods for detecting underivatized non-metabolized vitamin D by mass spectrometry.

A method for measuring aloesin in rat plasma includes: taking the to-be-detected plasma containing aloesin, adding the methanol solution containing the internal standard compound aloeresin D thereinto, performing vortex precipitation, centrifuging, and collecting supernatant as to-be-detected sample; setting liquid chromatogram conditions as follows: carrying out gradient elution by adopting a mobile phase A and a mobile phase B, wherein the mobile phase A is an aqueous solution containing 0.1-1.0 thousandth (v/v) of formic acid, the mobile phase B is methanol; Setting mass spectrometry conditions as follows: using electrospray ion source, using negative ion detection, spray voltage being 4500 V, spray temperature being 550° C.; adopting multiple reaction ion monitoring scan mode, wherein the ion pair used for the quantitative analysis of aloesin is m/z 393.1.fwdarw.272.9, and the ion pair for the internal standard compound aloeresin D is m/z 555.3.fwdarw.144.9. The method improves aloesin detection in plasma.

A method for the identification and localization of small molecule species in a histologic thin tissue section comprises the steps of: a) acquiring a mass/mobility image of the tissue section and generating a mass/mobility map of the small molecule species of interest for each pixel of the image; b) providing a second sample of the same tissue and extracting the small molecules of interest, separating them, and acquiring mass and ion mobility spectra from the separated small molecules; c) identifying the small molecules of interest using corresponding reference databases; and d) assigning identified small molecules to entries in the mass/mobility maps of the first tissue section by comparison of ion masses and mobilities of the identified species to those of the second thin tissue section.

A method for determining optimal values of a mass spectral operating parameter for mass spectral analysis of each of a plurality of compounds comprises: acquiring a plurality of mass spectral measurements of each of at least one characteristic ion species of each respective compound during its introduction into a mass spectrometer while a quantity of each introduced compound varies with time wherein, for each characteristic ion species, the operational parameter is caused to vary between successive mass spectral measurements of the said species; calculating, for each characteristic ion species, a corrected intensity of at least a portion of the plurality of mass spectral measurements of said each species, based on a best-fit synthetic model curve that relates to the time variation of the respective corresponding compound; and determining the optimal values of the operating parameter from analyses of variation of the corrected intensities with respect to the operational parameter variation.