A liquid chromatography measurement method includes: switching between a first measurement mode using a liquid chromatography method in which hemoglobin A1c and a hemoglobin variant are measured in a measurement sample by sequentially delivering a first component-separating eluent, a second component-separating eluent and a wash eluent to an analytical column, and a second measurement mode using the liquid chromatography method in which the hemoglobin A1c is measured by sequentially delivering the first component-separating eluent and the wash eluent to the analytical column; delivering the wash eluent in the first measurement mode prior to an influence from the second component-separating eluent disappearing such that a first retention time of the hemoglobin A1c in the first measurement mode and a second retention time of the hemoglobin A1c in the second measurement mode are substantially the same as each other; and delivering the first component-separating eluent after the wash eluent.

Methods are described for the automatic determination and correction of retention time shift of a MS data set relative to a control data set, to correct for retention time drifts endemic to targeted LCMS analyses. In an embodiment, a 2D grid of periodic MS spectra versus time is collected for a control experiment, and RT windows are determined with an additional set of unscheduled mass spectral analyses. During successive experiments, spectra from periodic MS scans are used to determine the correspondence between the current time and the time in the control experiment. The active set of MSn scans to be acquired by the instrument is then determined as the scans with adjusted retention time windows that bracket the corrected retention time.

The present invention relates to the field of diagnostic methods. Specifically, the present invention contemplates a method for diagnosing heart failure in a subject and a method for monitoring progression or regression of heart failure in a subject. The invention also relates to tools for carrying out the aforementioned methods, such as diagnostic devices.

Described herein are systems and techniques for improving operation of a gas chromatograph or a computer that identifies compounds that correspond to peaks in a graph of gas chromatograph data (chromatogram). Each of the peaks included in the chromatogram may be associated with retention times that are measured amounts of time that correspond to how long it took for respective compounds included in a sample to move through the gas chromatograph. Measured retention times may be compared to standard retention times to identify retention time shifts. These retention times shifts may correspond to a function that may be used to predict retention times of other compounds that could be included in the sample. When a measured retention time that is associated with an unclassified peak in the chromatogram matches a predicted retention time of a specific compound to a threshold level, the unclassified peak may be identified the specific compound.

A liquid chromatography method for identifying an analyte of interest utilizing as retention index standards a homologous series of neutrally charged compounds having at least one functional group bearing a positive charge and at least one functional group bearing a negative charge. The method is especially useful for liquid chromatography-mass spectrometry (LC-MS) methods, more especially for LC-MS methods employing electrospray (ESI) or atmospheric pressure chemical ionization (APCI) ionization systems.

A process for identifying an unknown compound in a sample includes matching a peak in a primary Fourier Transform Infrared spectral region of the sample spectrum with reference spectra in the same spectral region to generate an initial list of potential candidates, based, for example on goodness of fit criteria. The initial list can be reduced by retention time information and/or global peak matching techniques that analyze the sample spectrum in regions outside the primary region.

A GC sample carbon ladder is generated with the help of one or more of the following techniques: correction of solvent effects; fit analysis of the spectrum obtained for a target member of the carbon ladder and a reference spectrum; fit analysis of a sample carbon ladder in comparison with reference spectral features; constraints for proper order of elution; and/or inclusion of all members in a selected carbon ladder set.

A chromatograph device capable of correct measurement even if the retention times of target components change. This chromatograph device is provided with: a storage unit for storing measurement parameters for a plurality of target components, measurement conditions including measurement parameter switching times for each of two target components eluted in succession, and formulas for determining the switching times from predetermined retention times for the target components; a measurement data accumulation unit; a preceding-measurement-data determination unit for determining, at the time of sample measurement, whether there is preceding measurement data for the same column type, mobile phase type, and flow velocity; and a measurement execution unit for carrying out measurement on the basis of the measurement conditions if there is no preceding measurement data.

Methods for transferring a separation procedure from a first chromatographic system to a second one are disclosed that involve substantially matching a pressure profile. In some such methods, a length, an area, and a particle size of a first column in the first system and a flow rate in the first separation procedure are identifiable. Some such methods also involve selecting a combination of a length, an area, and a particle size of a second column in the second system and a flow rate for the second separation procedure. These methods may involve calculating a target length, a target area, or a target particle size for the second column in the second system or a target flow rate for the second separation procedure.

Methods for transferring a carbon dioxide based separation procedure from a reference chromatographic system to a target chromatographic system involve alternative techniques for determining system pressure drops not attributable to the column. One technique involves leveraging experimental chromatography to develop a correction factor that is a function of at least one correction coefficient and at least one ratio of the differential analyte retention time to the retention time in the reference system. Another technique involves leveraging other experimental measurements of tubing pressure drops under various condition to develop a lookup table that can be used to identify likely tubing pressure drops in the target system. A third technique leverages knowledge of the separation procedure and the target system and the likely nature of the relevant flow to calculate tubing pressure drops in the target system.