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.

Methods and system for identification of dimer species using online chromatography and electrospray ionization mass spectrometry are provided. Also provided are methods and system for quantitation of heterodimer species using immunoprecipitation and liquid chromatography-mass spectrometry.

A detection kit for detecting an immunosuppressor in whole blood by high performance liquid chromatography-tandem mass spectrometry and a detection method thereof is provided. An internal standard solution is added with an antioxidant, vitamin E, and mixed with an internal standard diluent containing zinc sulfate heptahydrate, purified water and methanol for sample pretreatment, which not only exerts the function of the internal standard, but also synchronously achieves erythrocyte treatment, protein precipitation and target substance extraction. Various embodiments enable the immunosuppressor to be more stable in a solution matrix, thus promoting the detection accuracy and sensitivity. Various embodiments adopt isotopically-labeled sirolimus as an internal standard of everolimus to substitute isotopically-labeled everolimus, thus overcoming the interference of everolimus on isotopically-labeled everolimus and satisfying the detection requirements. Various embodiments detect four immunosuppressors simultaneously to reduce the cost of the internal standard, and has a lower detection cost, more accurate and stable detection results.

Systems and methods for determining regions of proteins that contribute to self-association of the protein are provided. Methods for modifying the self-association of concentrated protein formulations are also provided.

Exemplary embodiments described herein provide improved techniques for matching an experimental mass spectrometry fragmentation against a known or predicted fragmentation from a library. Among other improvements, exemplary embodiments provide more accessible interfaces that are easier to interpret, thus allowing for more accurate and faster matches. They also may automatically accumulate multiple experimental results to determine whether several runs of a given sample cumulatively represent a library fragmentation pattern. Furthermore, exemplary embodiments provide simplified techniques for identifying and accounting for molecule variants.

Improved formulations for purification of peptide from biological samples and methods and kits for purifying peptides from biological samples (e.g., cells and tissues), as well as use of purified peptides (e.g., polypeptides derived from protein digests) in mass spectrometry (e.g., LC-MS) applications are described.

The present invention generally pertains to methods of quantifying free fatty acids in a pharmaceutical formulation. In particular, the present invention pertains to a method of quantifying free fatty acids released from polysorbate hydrolysis in a pharmaceutical formulation comprising a pharmaceutical product, polysorbate and free fatty acids, using liquid chromatography-mass spectrometry, without the use of an extraction step.

Systems and methods to characterize dimerization interfaces at the subdomain level of a protein are provided. An exemplary method includes digesting a protein dimer sample into subdomains, labeling the digested protein sample, isolating labeled dimeric and monomeric subdomain fragments, and peptide mapping the labeled sample to determine where the dimer fragments are labeled and where the dimer fragments are not labeled. Regions that show decreased labeling extents in the dimer fraction than that in the monomer fraction are likely involved or in close proximity to the dimerization interface.

A method comprises: aspirating a sample through a needle capillary into a chamber having first and second windows, the capillary and chamber both affixed to a moveable robotic arm; causing a light beam generated by a light source that is affixed to the robotic arm to pass through the sample between the windows; detecting, using a photodetector that is affixed to the robotic arm, a quantity of the light that passes through the sample and the windows; determining an optical absorbance of the sample and a concentration of an analyte in the sample from the detected quantity of light; determining a quantity of the sample to dispense into an analytical apparatus based on the determined concentration; moving the robotic arm so as to cause the needle capillary to mate with an inlet port of an analytical apparatus; and dispensing the determined quantity of the sample into the analytical apparatus.

The present invention provides rapid, sensitive high-throughput methods and systems for characterizing peptides or proteins using hydrophobic interaction chromatography-coupled native mass spectrometry to improve manufacturing process of biopharmaceutical products, such as identifying impurities during antibody purification, monitoring post-translational modification variants during production, or characterizing drug-to-antibody ratio of antibody-drug conjugates. The separation profiles of the peptides or proteins are generated and compared to identify or qualify the peptides or proteins.