The invention relates to the detection of vitamin D metabolites. In a particular aspect, the invention relates to methods for detecting derivatized vitamin D metabolites by mass spectrometry.

An automated dispersive liquid-liquid microextraction method of detecting and quanta N-nitrosamines in an aqueous sample. The method includes (a) extracting an aqueous solution containing the N-nitrosamines by mixing an extraction solvent and a dispersive solvent with the aqueous solution, such that the N-nitrosamines, or a portion thereof, re-distribute from the aqueous solution to the extraction solvent, (b) permitting the resulting mixture in (a) to form a two-phase mixture containing an aqueous phase comprising containing the aqueous solution with reduced amounts of the N-nitrosamines and an organic phase containing the extraction solvent with the N-nitrosamines extracted from the aqueous solution, (c) injecting the organic phase, or a portion thereof, into an injection port of a gas chromatograph coupled with at least one mass spectrometer, and (d) analyzing the N-nitrosamines by gas chromatography and mass spectrometry to detect and quantify the concentration of the N-nitrosamines in the aqueous solution.

A novel medical device that utilizes, for diagnosis and other medical uses, the detection of emitted radiofrequency (RF) signals experimentally shown as spontaneously emitted by a non-equilibrium population of spin polarized electrons in chiral media during their relaxation to equilibrium. The emitted RF signals correspond to the Zeeman spin-flip energy of electrons under the influence of a magnetic field (MF), which in the absence of an external MF are too difficult to detect. Using a larger MF shifts the low energy, low frequency RF emission of spin polarized electrons to a higher RF power emission wave characterized by a fixed resonant frequency. The detection of these higher RF power emissions is relatively easy using conventional MF magnet sources and antenna receiver technology.

The invention generally relates to methods and devices for synchronization of ion generation with cycling of a discontinuous atmospheric interface. In certain embodiments, the invention provides a system for analyzing a sample that includes a mass spectrometry probe that generates sample ions, a discontinuous atmospheric interface, and a mass analyzer, in which the system is configured such that ion formation is synchronized with cycling of the discontinuous atmospheric interface.

Provided are methods for determining the amount of lacosamide in a sample using mass spectrometry. The methods generally involve ionizing lacosamide in a sample and detecting and quantifying the amount of the ion to determine the amount of lacosamide in the sample.

The present invention is directed to a method and device to desorb an analyte using heat to allow desorption of the analyte molecules, where the desorbed analyte molecules are ionized with ambient temperature ionizing species. In various embodiments of the invention a current is passed through a mesh upon which the analyte molecules are present. The current heats the mesh and results in desorption of the analyte molecules which then interact with gas phase metastable neutral molecules or atoms to form analyte ions characteristic of the analyte molecules.

Provided are methods of detecting the presence or amount of a dihydroxyvitamin D metabolite in a sample using mass spectrometry. The methods generally comprise ionizing a dihydorxyvitamin D metabolite in a sample and detecting the amount of the ion to determine the presence or amount of the vitamin D metabolite in the sample. In certain preferred embodiments the methods include immunopurifying the dihydroxyvitamin D metabolites prior to mass spectrometry. Also provided are methods to detect the presence or amount of two or more dihydroxyvitamin D metabolites in a single assay.

The invention provides mass spectrometry methods, compositions and systems which enable a unique platform for analyte quantitation accessing very high degrees of multiplexing and accurate quantification, particularly well-suited for a range of quantitative analysis for proteomics applications. Embodiments of the present methods and systems combine isotopic coding agents characterized by very small differences in molecular mass with mass spectrometry methods providing large resolving power to provide relative or absolute analyte quantification in a large number of samples.

A method for analyzing aromatic compounds, and a reagent kit for LC-MS analysis of aromatic compounds. The method includes preparing a diazonium reagent, contacting aromatic compounds in a sample with the diazonium reagent to form an analyte; and measuring an amount or ratio of the analyte. The reagent kit includes a diazonium reagent, wherein the diazonium reagent includes (i) a diazonium salt that contains a diazonium ion; (ii) an amine and nitrous acid; and/or (iii) a nitrite and an acid.

This invention concerns a method for analysing the ageing stability of a bituminous binder, in particular by reference to its susceptibility to oxidation, by analysing a sample of the bituminous binder by means of electron spin resonance and measuring the integral of the signal of the carbon-centred stable radicals; accelerated ageing of the bituminous binder, comprising: i) heating the bituminous binder, followed by ii) heating the bituminous binder resulting from step i) under pressure; analysing a sample of the aged bituminous binder obtained from step b) by means of electron spin resonance and measuring the integral of the signal of the carbon-centred stable radicals; and comparing the integral of the signal of the carbon-centred stable radicals of the bituminous binder obtained from the first step and that obtained from the previous step.