A method for determining in a sample, by mass spectrometry, the amount of one or more analytes is described. The method comprises introducing a 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 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.

A method for evaluating a mass spectrometry device includes: by a mass spectrometry device, performing mass spectrometry of an ester of phthalic acid and detecting a plurality of types of ions produced by dissociation of the ester of phthalic acid; and obtaining information concerning whether the mass spectrometry device is in a state suitable for analysis, based on a ratio of intensities of the plurality of types of ions detected.

A liquid chromatograph mass spectrometer specifying a location where a flow path is clogged and recovering in a short time. The liquid chromatograph mass spectrometer includes a first flow path passing through a separation column, a second flow path not passing through the separation column, a mass spectrometry unit on the downstream side of the first and second flow paths and analyzes a sample that has passed through the first flow path, a first valve for connecting any one of the first and second flow paths to the mass spectrometry unit, and a controller for controlling driving of the first valve, connecting the first flow path to the mass spectrometric unit, comparing the measured value of the mass spectrometric unit with a predetermined threshold value, and connecting the second flow path to the mass spectrometry unit when it is determined to be abnormal.

A method of mass spectrometry is disclosed comprising: a) separating first ions or components of an analyte sample according to a physicochemical property other than ion mobility; b) separating said first ions or second ions formed from said components according to ion mobility; c) detecting the intensities of said first ions, or detecting the intensities of second ions formed from said components, or detecting the intensities of ions derived from said first or second ions; wherein the intensity of the ions detected at any given time is recorded together with an associated value of said physicochemical property and an associated value of said ion mobility so as to obtain spectral data; d) examining the intensities of the spectral data as a function of said ion mobility so as to detect an intensity peak in said spectral data, determining a discrete value of ion mobility for said peak, and defining a window of values of ion mobility that encompasses said discrete value; and e) filtering said spectral data so as to include only spectral data that has been associated with values of ion mobility that are within said window of ion mobility values.

A panel of metabolic biomarkers for differential diagnosis of stable angina pectoris and acute coronary syndrome is published herein. The panel comprises one or more of the metabolic biomarkers, including malic acid, taurine, arachidonic acid, citramalic acid, methionine, pentadecanoic acid. Single use of the 6 differential metabolites provided clinically diagnostic value of SA vs. ACS with AUC>0.7. When combined, the more metabolites, the larger of AUC. The highest AUC of 0.987 was obtained when all of the six metabolites were combined to distinguish SA vs. ACS with sensitivity 96.8% and specificity 97.7% using optimal cut-off value. The metabolic biomarkers provided by the invention can be used for differential diagnosis of SA vs. ACS of high accuracy, sensitivity and specificity.

The invention relates to a method for the determination of crocetin and its derivative amounts and the derivative composition from gardenia yellow. The method mainly comprises of following steps: the absorbance measurement of a gardenia yellow aqueous solution at known concentration by UV-VIS, the absorption coefficient measurement of total crocetin derivative, the total crocetin derivative amount calculation according to Lambert-Beer law, the relative amount calculation of each crocetin derivative from its absorption coefficient and peak area on HPLC, the amount calculation of each crocetin derivative from the total amount of crocetin derivative and the relative amount of each crocetin derivative, and finally total crocetin amount calculation. In practice, the absorption coefficient of each crocetin derivative is calculated from that of its root structure, crocetin, based on the negative correlation-ship of absorbance with molecular mass of the molecule while the molecular mass of each crocetin derivative is substituted by the m/z value of its parent ion.

The present invention is based on the finding that enrichment of D3-creatinine in a urine sample following oral administration of a single defined dose of D3-creatine can be used to calculate total-body creatine pool size and total body skeletal muscle mass in a subject. The invention further encompasses methods for detecting creatinine and D3-creatinine in a single sample. The methods of the invention find use, inter alia, in diagnosing disorders related to skeletal muscle mass, and in screening potential therapeutic agents to determine their effects on muscle mass.

The invention relates to a method for determining the presence of at least one distinct polypeptide in a biological sample comprising contacting the biological sample with a hydrolyzing agent, wherein the hydrolyzing agent is capable of hydrolyzing the distinct polypeptide in a sequence-specific manner such that at least one distinct peptide having a predetermined peptide measured accurate mass would result if the at least one distinct polypeptide were present in the biological sample, to obtain a hydrolyzed sample; bringing the hydrolyzed sample in contact with a substrate comprising at least one immobilized binding partner, wherein the at least one immobilized binding partner is capable of specifically binding the distinct peptide; removing the hydrolyzed sample from the substrate in a manner such that the distinct peptide would remain bound to the immobilized binding partner; contacting the substrate with an elution solution, wherein the distinct peptide would dissociate from the immobilized binding partner into the elution solution; subjecting a portion of the elution solution to liquid chromatography to segregate a plurality of molecules in the portion of the elution solution to obtain sorted molecules; determining the measured accurate mass of at least one sorted molecule present in the elution solution; and determining the presence of the at least one distinct polypeptide in the biological sample when a measured accurate mass of at least one molecule is substantially equal to the predetermined peptide measured accurate mass.

Provided are methods for determining the amount of tamoxifen and its metabolites in a sample by mass spectrometry. In some aspects, the methods provided herein determine the amount of norendoxifen. In some aspects, the methods provided herein determine the amount of norendoxifen and tamoxifen. In some aspects, the methods provided herein determine the amount of norendoxifen and other tamoxifen metabolites. In some aspects, the methods provided herein determine the amount of tamoxifen, norendoxifen, and other tamoxifen metabolites.

The invention relates to poly-amide bonded hydrophilic interaction chromatography (HILIC) stationary phases and novel HILIC methods for use in the characterization of large biological molecules modified with polar groups, known to those skilled in the art as glycans. The invention particularly provides novel, poly-amide bonded materials designed for efficient separation of large biomolecules, e.g. materials having a large percentage of larger pores (i.e. wide pores). Furthermore, the invention advantageously provides novel HILIC methods that can be used in combination with the stationary phase materials described herein to effectively separate protein and peptide glycoforms by eliminating previously unsolved problems, such as on-column aggregation of protein samples, low sensitivity of chromatographic detection of the glycan moieties, and low resolution of peaks due to restricted pore diffusion and long intra/inter-particle diffusion distances.