The disclosure relates to a method for measuring the amount of a target protein in body fluid. The method comprises preparing a sample suspected to comprise a target protein and adding a known amount of an isotope-labelled internal standard protein consisting of a fragment of the target protein. Furthermore, the method comprises bringing the sample into contact with a solid support comprising a binding agent. The target protein and the standard protein are thereafter digested to form a digested sample which is subjected to mass spectrometry, so as to determine the amount of the target protein in the sample by comparing with the standard protein. The disclosure further relates to a kit comprising at least one binding agent, at least one isotope-labelled internal standard protein, and instructions for carrying out the method.

A method for determining whether a subject has a disease or condition or is at risk of developing a disease or condition is disclosed. A method for determining whether a subject is at risk of developing an infectious disease or a complication thereof is also disclosed.

The disclosure describes a comprehensive metabolome analysis of urine samples that identified panels of metabolite markers for diagnosis and monitoring of alloimmune injury, acute rejection, and BK virus nephropathy. The disclosure provides non-invasive ways to monitor the status of transplanted kidneys by monitoring the presence of defined metabolite panels over a period of time. The metabolite panels of the disclosure can distinguish the between kidney injuries of distinct etiology with high sensitivity and specificity.

The present invention generally pertains to methods of preventing disulfide scrambling in non-reducing liquid chromatography-mass spectrometry analysis of a protein of interest. In particular, the present invention pertains to the addition of maleimide to a non-reducing liquid chromatography-mass spectrometry analysis of a protein to prevent disulfide scrambling.

A method and a device for protein sequence analysis, and the use of microdroplets for improving protein sequencing by accelerating enzymatic digestion, wherein the method comprises the following steps: a) forming a solution containing protein into microdroplets having a size small enough to result in acceleration of protein digestion; b) introducing the microdroplets into a mass spectrometer (MS) for real-time detection; c) obtaining analysis result of the protein from the mass spectrometer (MS); wherein the protein is fully digested in the microdroplets before entering the mass spectrometer (MS). The method and device can achieve simple and nearly complete protein digestion in a very short time and obtain high sequence coverage.

The present invention provides methods and systems to identify host cell protein (HCP) impurities in a sample containing high-abundance proteins. The HCP impurities can be enriched using interacting peptide ligands which have been attached to solid support. The HCP impurities can be eluted from the solid support. The isolated HCP impurities can be subjected to limited digestion to generate components of the isolated HCP impurities which can subsequently be identified using a mass spectrometer. The present invention also provides methods and systems to identify sequence variant (SV) peptides or proteins in a sample containing high-abundance proteins. The SV peptides or proteins can be enriched using interacting peptide ligands which have been attached to solid support. The SV peptides or proteins can be eluted from the solid support. The isolated SV peptides or proteins can be subjected to full or limited digestion to generate components of the isolated SV peptides or proteins which can subsequently be identified using a mass spectrometer.

Described are an apparatus for generating and collecting nanospray reactive droplets and a method for analyzing a protein digestion. The apparatus includes a capillary, counter electrode, collection vessel, electrostatic lenses, and voltage control module. The capillary receives a mixture that includes a protein and an enzyme and has an outlet disposed in the aperture to dispense the mixture. The collection vessel has a concave surface to receive a nanospray plume emitted from the capillary outlet. The counter electrode and electrostatic lenses are disposed along a nanospray path defined between the capillary outlet and the collection vessel. Each electrostatic lens is formed of an electrically conductive plate having an aperture therein to pass a nanospray reactive plume. The voltage control module is in electrical communication with and is configured to independently control the voltage of the capillary, the counter electrode, the collection vessel and each of the electrostatic lenses.

The present disclosure relates to methods and workflows for processing and analyzing clinical samples (e.g., nasal swabs, throat swabs, plasma samples, urine, etc.) In general, the methods and workflows involve the detection of an infectious state and are improved over contemporary methods due to increased throughput with improved resolution of positive results.

Method and devices for performing top down analysis of an antibody are described which involve utilizing an ion source to generate a plurality of ions from a sample containing at least one intact antibody. Further, transmitting said plurality of ions through a quadrupole rod set while applying an RF signal thereto and in the absence of a resolving DC voltage so as to preferentially transmit precursor ions having an m/z value greater than a low mass cutoff of about 1500 m/z from the quadrupole rod set to an ECD cell. The method and device can also performing an ECD reaction in the ECD cell on said precursor ions and also detect reaction products from the ECD reaction.

Various embodiments of the present disclosure relate to a method for analyzing target compounds from a fluid or dried biological sample by using a microfluidic sample device including a hollow cartridge and an absorbent body unit.