Abstract: Processes and methods for modeling non-linear calibration behavior resulting from isotopic interference between a target analyte and an internal standard during a mass spectrometry operation are disclosed and described. In some embodiments, a correction to instrument data obtained during the mass spectrometry operation can be made. Such a correction may entail determining, in some cases experimentally determining, one or two constants, and a single adjustable parameter for each analyte/internal standard pair.

Abstract: The present disclosure provides methods and composition involving increased sensitivity of compounds using mass spectrometry. In one embodiment, a method of increasing the sensitivity for detection of a carbonyl group-containing compound by mass spectrometry can comprise derivatizing the carbonyl group-containing compound with an O-substituted hydroxylamine thereby producing an oxime, resulting in enhanced sensitivity of detection by mass spectrometry, as compared to the underivatized carbonyl group-containing compound. Additionally, a method for assaying a carbonyl group-containing compound can comprise reacting the carbonyl group-containing compound in a sample with an O-substituted hydroxylamine to produce an oxime and performing analysis with mass spectrometric detection of the oxime by a mass spectrometry instrument.

Abstract: The present invention provides methods for determining the amount of cis-diol containing compounds in a biological samples using mass spectrometry, particularly catecholamines (dopamine, epinephrine, norepinephrine) in a plasma sample. After a sample is mixed with an internal standard, extracted with a two-step liquid-liquid extraction process utilizing phenylboronic acid chemistry, and then derivatized with a benzoyl chloride-like agent, relevant moieties are then separated chromatographically and detected by MS/MS whereby specific ion transitions are monitored. This invention has several clinical utilities, particularly those related to measuring plasma catecholamines in patients.

Abstract: The present invention provides methods for determining the amount of cis-diol containing compounds in a biological samples using mass spectrometry, particularly catecholamines (dopamine, epinephrine, norepinephrine) in a plasma sample. After a sample is mixed with an internal standard, extracted with a two-step liquid-liquid extraction process utilizing phenylboronic acid chemistry, and then derivatized with a benzoyl chloride-like agent, relevant moieties are then separated chromatographically and detected by MS/MS whereby specific ion transitions are monitored. This invention has several clinical utilities, particularly those related to measuring plasma catecholamines in patients.

Abstract: The present disclosure provides methods and composition involving increased sensitivity of compounds using mass spectrometry. In one embodiment, a method of increasing the sensitivity for detection of a carbonyl group-containing compound by mass spectrometry can comprise derivatizing the carbonyl group-containing compound with an O-substituted hydroxylamine thereby producing an oxime, resulting in enhanced sensitivity of detection by mass spectrometry, as compared to the underivatized carbonyl group-containing compound. Additionally, a method for assaying a carbonyl group-containing compound can comprise reacting the carbonyl group-containing compound in a sample with an O-substituted hydroxylamine to produce an oxime and performing analysis with mass spectrometric detection of the oxime by a mass spectrometry instrument.

Abstract: A radio-frequency quadrupole ion guide having a symmetrical magnetic field disposed along an axis of the ion guide, wherein the system provides prolonged interaction between electrons and uncharged compounds within an ionization volume of the ion guide, resulting in enhanced ion creation.

Abstract: A radio-frequency quadrupole ion guide having a symmetrical magnetic field disposed along an axis of the ion guide, wherein the system provides prolonged interaction between electrons and uncharged compounds within an ionization volume of the ion guide, resulting in enhanced ion creation.