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 method for reducing the variability, as measured by relative standard deviation (RSD), of an analytical testing technique is provided. This improvement in RSD improves the confidence in the values obtained during field testing. The method includes incorporating a focusing agent into the sampling media, which permits providing sampling media such as thermal desorption tubes preloaded with the focusing agent.

A plurality of measured product ion spectra is produced using a DIA tandem mass spectrometry method. One or more product ions are retrieved from a spectral library of known compounds or one or more theoretical product ions are calculated for the known compounds of a database. For each known or theoretical product ion, an XIC is calculated from the measured product ion spectra. Measured XIC peaks above a threshold intensity are grouped for the known compounds producing a subset of known compounds. Known or theoretical retention times are retrieved or calculated for the subset of known compounds. A regression function is calculated to correct the known or theoretical retention times using the known or theoretical retention times of the subset of known compounds as the independent variables and the measured retention times of the measured XIC peak groups of the subset of known compounds as the dependent variables.

A method for reducing the variability, as measured by relative standard deviation (RSD), of an analytical testing technique is provided. This improvement in RSD improves the confidence in the values obtained during field testing. The method includes incorporating a focusing agent into the sampling media, which permits providing sampling media such as thermal desorption tubes preloaded with the focusing agent.

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.

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.

A thermal desorption tube for chromatography and mass spectrometry analysis. The thermal desorption tube includes a sorbent and a plurality of focusing agents loaded at known, relative amounts onto the sorbent. Each focusing agent is a compound that chromatographically elutes within a retention time similar to a retention time of a target analyte and has a mass spectrum similar to a mass spectrum of the target analyte. The thermal desorption tube is configured to be further loaded with a sample having the target analyte.

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.

A method of calibrating, a chromatography system is described. The method includes injecting a standard into a chromatographic separator. The standard including a first analyte having a first calibrant concentration and a second analyte having a second calibrant concentration. The standard can be separated in the chromatographic separator and measured with a detector. The method automatically identifies whether the first peak corresponds to the first analyte or the second analyte and whether the second peak corresponds to the first analyte or the second analyte, based on either an area or a peak height of the first peak and the second peak, and a ratio based on the first calibrant concentration and the second calibrant concentration.