Abstract: Methods and systems for adjusting instrument setting, improving fidelity of isotope pattern for mass spectra, and/or determining molecular mass with improved accuracy are disclosed. In one example, a method for determining Mmono of a compound of interest in a sample using a mass spectrometer is provided. The method comprises: (1) tuning or adjusting instrument setting of the mass spectrometer using at least one known compound, wherein the instrument setting comprises at least one parameter for improving accuracy; (2) analyzing the compound of interest using the adjusted instrument setting to obtain a mass spectrum thereof, wherein the mass spectrum comprises an isotope pattern thereof; and determining the Mmono of the compound of interest from the mass spectrum thereof.

Abstract: Methods and systems for identifying analytes in a sample using mass spectrometry are provided. A method for identifying analytes in mass spectrometry data comprises: introducing a sample to a mass spectrometer; analyzing the sample with the mass spectrometer in a plurality of cycles; generating, for each cycle, a mass spectrum comprising at least one peak; annotating peaks in the mass spectrum based on their relationships; assigning best ion types to each peak; processing each cycle of the mass spectrum to assign a score to each of the at least one peak thereof with respect to the likely neutral mass related to the peak; grouping peaks that share a common neutral mass; and outputting the analyte neutral mass.

Abstract: Methods and systems for building and using an analyte library are provided. One aspect is a method for building an analyte library, the method comprising receiving mass spectrum data from analysis of a sample using mass spectrometry, mass spectrum data including a mass spectrum and a sample matrix, and the sample including an analyte, identifying peaks in the mass spectrum, assigning at least one ion type to the peaks, annotating the peaks for the analyte based on the sample matrix, extracting an ion fingerprint for the analyte based on the annotated peaks and storing an analyte identification entry including the ion fingerprint for the analyte.

Abstract: Methods and systems for identifying one or more analytes in a sample are provided. One aspect is a method of predicting an identity of analytes in an unknown sample, the method comprising accessing a database comprising a plurality of results from analyzing samples using mass spectrometry to identify analytes, the plurality of results including annotated ion fingerprints, training a machine learning model with the plurality of results, and applying the machine learning model to the unknown sample to predict an identity of one or more analytes in the unknown sample.

Abstract: A method for identifying peaks in a mass spectrum is provided. The method includes: accessing a mass spectrum (300), having an intensity signal, generated for analysis of a sample; performing a wavelet transformation on the intensity signal to generate a wavelet space representation (310) of the intensity signal; generating a scale-space-processing (SSP) response signal (412, 414, 416) from the wavelet space representation of the intensity signal, wherein the SSP response signal (412, 414, 416) represents the SSP response from the wavelet scale representation (310) at different wavelet scales for a particular m/z starting position (312, 314, 316); identifying a first wavelet scale for a first local maximum in the SSP response signal; based on the first wavelet scale, detect a first baseline intensity signal; subtracting the first baseline intensity signal from the intensity signal to generate a first adjusted intensity signal; and detecting one or more peaks in the first adjusted intensity signal.

Abstract: An automated method of operating a mass spectrometer (MS) comprising a differential mobility spectrometer (DMS) includes: introducing a first compound to the DMS; calculating a first alpha function for the first compound; introducing a second compound to the DMS; calculating a second alpha function for the second compound; and determining operation parameters of the DMS to achieve sufficient separation of the first compound and the second compound, based on the first alpha function and the second alpha function.

Abstract: A method of operating a system including a differential mobility spectrometer (DMS) and a mass spectrometer. A sample is introduced to the DMS. The sample is analyzed with the DMS. Data is generated based at least in part on an analyte ion generated from the sample and at least one transport gas composition. Library data of the analyte ion is accessed from a library. The generated data is compared to the library data. A signal is sent when the generated data deviates from the library data by more than a predetermined threshold.

Abstract: In one aspect, a computer implemented method for determining expected cleavage products of a macromolecule includes defining at least one residue of the macromolecule as having a core and at least one linker, where said at least one linker is defined as a sequence of two or more structural units that are coupled to one another via one or more chemical bonds. A digital data processor can be utilized to determine one or more expected bond cleavages, if any, between the structural units of said at least one linker and between adjacent residues when the macromolecule undergoes cleavage, e.g., in response to application of energy thereto, so as to predict expected cleavage products of the macromolecule.

Abstract: Each of one or more unknown compounds are separated from a sample over a separation time period. Separated compounds are ionized, producing one or more compound precursor ions for each of the unknown compounds and a plurality of background precursor ions. A precursor ion mass spectrum is measured for the combined compound and background precursor ions at each time step of a plurality of time steps spread across the separation time period, producing a plurality of precursor ion mass spectra. One or more background precursor ions are selected from the plurality of precursor ion mass spectra that have a resolving power in a range below a threshold expected resolving power. A separation time is detected for an unknown compound when a decrease in an intensity measurement of the selected background precursor ions over a time period exceeds a threshold decrease in intensity with respect to time.

Abstract: At least one molecule is ionized and a mass spectrometer mass analyzes an m/z range, producing an m/z mass spectrum. A range of N sequential charge states is received. A copy of the m/z mass spectrum is created for each of the N charge states, producing N m/z spectra. Each spectrum of the N spectra is converted to a neutral mass mass spectrum using a different charge state of the N charge states, producing N neutral mass mass spectra. The N neutral mass mass spectra are aligned by neutral mass. When two or more spectra of the N neutral mass mass spectra corresponding to two or more different and sequential charge states include a neutral mass peak above a predetermined intensity threshold at a neutral mass value within a predetermined neutral mass tolerance, the neutral mass value is identified as a neutral mass of the at least one molecule.

Abstract: Each of one or more unknown compounds are separated from a sample over a separation time period. Separated compounds are ionized, producing one or more compound precursor ions for each of the unknown compounds and a plurality of background precursor ions. A precursor ion mass spectrum is measured for the combined compound and background precursor ions at each time step of a plurality of time steps spread across the separation time period, producing a plurality of precursor ion mass spectra. One or more background precursor ions are selected from the plurality of precursor ion mass spectra that have a resolving power in a range below a threshold expected resolving power. A separation time is detected for an unknown compound when a decrease in an intensity measurement of the selected background precursor ions over a time period exceeds a threshold decrease in intensity with respect to time.

Abstract: Known lipid molecules of a matrix are grouped into lipid classes and the lipid classes are further grouped into a pass-through group and a mobility separation group based on isobaric interferences. A separation system separates known lipid molecules from a matrix sample and an ion source ionizes the matrix sample. Two injections are performed. For the first injection a DMS device is put into passive mode, and for the second injection the DMS device is used to resolve isobaric interferences. A tandem mass spectrometer performs MRM scans of the pass-through group for the first injection and MRM scans of the mobility separation group for the second injection. A processor quantitates each lipid molecule in the matrix sample by comparing the MRM intensity values obtained for the first and second injections to MRM intensity and concentration values for known standards of the known lipid molecules of the matrix.

Abstract: A metabolized product ion spectrum is produced for a metabolized version of a known compound using tandem mass spectrometry. Metabolized structures are inferred from the metabolized product ion spectrum. An unmetabolized product ion spectrum is received for an unmetabolized version of the known compound and unmetabolized structures are inferred from the unmetabolized product ion spectrum. Each of the metabolized structures is compared to the unmetabolized structures, producing matched and unmatched structures. For each unmatched structure, a biotransformation repository is searched for modifications and each unmatched structure and the modifications found are again compared to the unmetabolized structures, producing modified matched structures. For each atomic index of the known compound, an unmodified specificity is calculated from the matched structures, a modified intensity specificity is calculated from the modified matched structures, and a score is calculated from the specificities.

Abstract: At least one product ion mass spectrum produced by a tandem mass spectrometer is received. A chemical structure of a compound that corresponds to the at least one product ion mass spectrum is received. One or more elemental compositions are assigned to at least one peak in the at least one product ion spectrum based on the chemical structure using the processor. At least one elemental composition of the one or more assigned elemental compositions is selected for the at least one peak using the processor. The mass of the at least one peak is converted to the mass of the selected at least one elemental composition using the processor, producing a product ion mass spectrum with higher mass accuracy.

Abstract: Systems and methods are provided for providing a DMS precursor ion survey scan. An ion source configured to receive a sample is instructed to ionize the sample using a processor. A DMS device configured to receive ions from the ion source is instructed to separate precursor ions received from the ion source and transmit precursor ions using two or more CoVs using the processor. A mass analyzer configured to receive transmitted precursor ions from the DMS device is instructed to measure the m/z intensities of the transmitted precursor ions across an m/z range at each CoV of the two or more CoVs using the processor. The measured m/z intensities of the transmitted precursor ions received from the mass analyzer are stored as a function of m/z value and CoV using the processor. This produces a stored two-dimensional mapping of m/z intensities of the precursor ions of the sample.

Abstract: A metabolized product ion spectrum is produced for a metabolized version of a known compound using tandem mass spectrometry. Metabolized structures are inferred from the metabolized product ion spectrum. An unmetabolized product ion spectrum is received for an unmetabolized version of the known compound and unmetabolized structures are inferred from the unmetabolized product ion spectrum. Each of the metabolized structures is compared to the unmetabolized structures, producing matched and unmatched structures. For each unmatched structure, a biotransformation repository is searched for modifications and each unmatched structure and the modifications found are again compared to the unmetabolized structures, producing modified matched structures. For each atomic index of the known compound, an unmodified specificity is calculated from the matched structures, a modified intensity specificity is calculated from the modified matched structures, and a score is calculated from the specificities.

Abstract: Known lipid molecules of a matrix are grouped into lipid classes and the lipid classes are further grouped into a pass-through group and a mobility separation group based on isobaric interferences. A separation system separates known lipid molecules from a matrix sample and an ion source ionizes the matrix sample. Two injections are performed. For the first injection a DMS device is put into passive mode, and for the second injection the DMS device is used to resolve isobaric interferences. A tandem mass spectrometer performs MRM scans of the pass-through group for the first injection and MRM scans of the mobility separation group for the second injection. A processor quantitates each lipid molecule in the matrix sample by comparing the MRM intensity values obtained for the first and second injections to MRM intensity and concentration values for known standards of the known lipid molecules of the matrix.

Abstract: Systems and methods are provided for providing a DMS precursor ion survey scan. An ion source configured to receive a sample is instructed to ionize the sample using a processor. A DMS device configured to receive ions from the ion source is instructed to separate precursor ions received from the ion source and transmit precursor ions using two or more CoVs using the processor. A mass analyzer configured to receive transmitted precursor ions from the DMS device is instructed to measure the m/z intensities of the transmitted precursor ions across an m/z range at each CoV of the two or more CoVs using the processor. The measured m/z intensities of the transmitted precursor ions received from the mass analyzer are stored as a function of m/z value and CoV using the processor. This produces a stored two-dimensional mapping of m/z intensities of the precursor ions of the sample.

Abstract: At least one product ion mass spectrum produced by a tandem mass spectrometer is received. A chemical structure of a compound that corresponds to the at least one product ion mass spectrum is received. One or more elemental compositions are assigned to at least one peak in the at least one product ion spectrum based on the chemical structure using the processor. At least one elemental composition of the one or more assigned elemental compositions is selected for the at least one peak using the processor. The mass of the at least one peak is converted to the mass of the selected at least one elemental composition using the processor, producing a product ion mass spectrum with higher mass accuracy.

Abstract: The applicants' teachings provide in some aspects methods and apparatus for mass spectrometric analysis that identify the location of carbon-carbon double bonds, if any, in an analyte by (1) obtaining the m/z ratio of the intact analyte ions, (2) subjecting these ions to collision-induced dissociation and (3) determining relationships between masses and/or mass-to-charge ratios of the intact analyte ions and the fragments produced by such collision-induced dissociation. The methods and apparatus selectively subject analyte ions to ozone-induced dissociation based on those relationships and determine location(s) of carbon-carbon double bonds, if any, from reaction products of ozone-induced dissociation.