A method of quantifying a target compound includes applying an oxidation/reduction potential to an electrochemical cell (14); measuring an electrochemical current during the application of the oxidation/reduction potential; and ionizing and directing the target compound before and after the application of the oxidation/reduction potential to a mass spectrometer (16) that measures a target compound ion intensity. The method further includes determining a target compound ion intensity change due to the application of the oxidation/reduction potential and determining a total amount of the target compound in the sample using the measured electrochemical current and the target compound ion intensity change. Determining the target compound ion intensity change may comprise either comparing the target compound ion intensity before and after the electrolysis relative to a reference peak or comparing the integrated peak area of a target compound ion in an extracted ion chromatogram before and after the electrolysis.

Provided are methods for determining the apolipoprotein E (ApoE) phenotype in a sample by mass spectrometry; wherein the ApoE allele(s) present in the sample is determined from the identity of the ions detected by mass spectrometry. In another aspect, provided herein are methods for diagnosis or prognosis of Alzheimer's disease or dementia.

The disclosure features methods and systems that include directing an ion beam to a region of a sample to liberate charged particles from the region of the sample, where the directed ion beam is pulsed at a first repetition rate, deflecting a first subset of the liberated charged particles from a first path to a second path different from the first path in response to a gate signal synchronized with the repetition rate of the pulsed ion beam, and detecting the first subset of the liberated charged particles in a time-of-flight (TOF) mass spectrometer to determine information about the sample, where the gate signal sets a common reference time for the TOF mass spectrometer for the first subset of charged particles liberated by each pulse of the ion beam.

An analysis method incudes: preparing a sample containing microorganisms; placing the microorganisms under a first condition and then performing a first mass spectrometry on a substance produced by the microorganisms; and obtaining information on characteristics or classifications of the microorganisms contained in the sample on a basis of a difference between a first data obtained in the first mass spectrometry and a second data obtained when a second mass spectrometry is performed on a substance produced by the microorganisms after having been placed under a second condition as well as a reference data in which classifications or characteristics of the microorganisms are associated with the data obtained in the mass spectrometry of the microorganisms, in which the first condition and the second condition differ in a sugar concentration or an oxygen concentration in an environment in which the microorganisms are placed.

The present invention relates to a method for quantitative measurement of catechol estrogen bound protein in blood sample. By detecting adduction levels of binding sites of the catechol estrogen on the protein in blood sample, the catechol estrogen bound protein in the blood sample can be detected quantitatively and a limit of quantitation can be decreased.

Embodiments described herein generally relate to technologies for analyzing peptide structures for diagnosing and/or treating a disease state advancing through a disease progression. A non-limiting example of a method relating to the technologies described in the subject application may include receiving peptide structure data corresponding to the biological sample obtained from the subject, identifying a peptide structure profile, and diagnosing a disease state within a disease progression. The example may further include generating a diagnosis output relating to the disease state. In at least some cases, the peptide structure profile may include glycosylated peptides, aglycosylated peptides, or both.

Methods for derivatization of biomolecules including glycans or other biopolymers with one or more fluorescent, MS active compounds by reductive amination or rapid tagging in order to produce derivatized glycan having a pKa>7 and between about 200 Å.sup.2 and about 1000 Å.sup.2 of nonpolar surface area are described.

The present invention relates to use of an isobaric label in mass spectrometry (MS) analysis using data-independent acquisition (DIA), wherein said isobaric label comprises or consists of a group which fragments in the mass spectrometer (i) at an energy below the energy required for fragmenting analyte-derived precursor ions and/or a higher conversion rate than said precursor ions; and (ii) at said energy according to (i) and when coupled to a precursor ion, at a single site within said group, to yield a first moiety and a second moiety, said second moiety being coupled to said precursor ion.

Disclosed is a method for identifying methicillin-resistant Staphylococcus aureus through detection a mass signal at m/z of 6580-6600 in the MALDI-TOF mass spectrum. Also disclosed is a novel peptide biomarker, which consists of SEQ NO ID:5 and the use thereof for detection and/or identification of methicillin-resistant Staphylococcus aureus.

Methods for determining an in vitro release profile of peanut allergens in a sample are provided. Methods for determining one or more signatures of peanut allergens in a sample are provided.