Methods for determining the amount of vitamin D compounds in a sample are provided. The methods can employ LC-MS/MS techniques and optionally the use of deuterated internal standards. Methods for diagnosing vitamin D deficiencies are also provided.

Methods for determining the amount of vitamin D compounds in a sample are provided. The methods can employ LC-MS/MS techniques and optionally the use of deuterated internal standards. Methods for diagnosing vitamin D deficiencies are also provided.

Methods for determining the amount of vitamin D compounds in a sample are provided. The methods can employ LC-MS/MS techniques and optionally the use of deuterated internal standards. Methods for diagnosing vitamin D deficiencies are also provided.

An apparatus is provided for sensing an analyte in a fluid. The apparatus includes a fluid collecting device configured to collect the fluid containing the analyte; a fluid input in fluid communication with the fluid collecting device configured to input the fluid containing the analyte into the fluid collecting device, an analyte interactant in fluid communication with the fluid collecting device, wherein the analyte interactant, when contacted by the analyte, reacts to cause a first change in thermal energy within the fluid collecting device; a modulator that causes a second change in thermal energy; a thermal sensing device comprising at least one pyroelectric device thermally coupled to the fluid collecting device to generate a first signal in response to at least one of the first change in thermal energy and the second change in thermal energy; a control device operatively coupled to the thermal sensing device and the modulator that generates a second signal, wherein the second signal comprises information useful in characterizing the analyte. A related method also is disclosed.

This disclosure provides 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 comprises (i) a diazonium salt that contains a diazonium ion; (ii) an amine and nitrous acid; and/or (iii) a nitrite and an acid.

Methods for determining the amount of vitamin D compounds in a sample are provided. The methods can employ LC-MS/MS techniques and optionally the use of deuterated internal standards. Methods for diagnosing vitamin D deficiencies are also provided.

An apparatus is provided for sensing an analyte in a fluid. The apparatus includes a fluid collecting device configured to collect the fluid containing the analyte; a fluid input in fluid communication with the fluid collecting device configured to input the fluid containing the analyte into the fluid collecting device, an analyte interactant in fluid communication with the fluid collecting device, wherein the analyte interactant, when contacted by the analyte, reacts to cause a first change in thermal energy within the fluid collecting device; a modulator that causes a second change in thermal energy; a thermal sensing device comprising at least one pyroelectric device thermally coupled to the fluid collecting device to generate a first signal in response to at least one of the first change in thermal energy and the second change in thermal energy; a control device operatively coupled to the thermal sensing device and the modulator that generates a second signal, wherein the second signal comprises information useful in characterizing the analyte. A related method also is disclosed.

A sampling system includes an analyte sampler that includes an enclosure; a mount disposed in the enclosure; a capillary tube disposed in the mount; and a thermal member disposed in the enclosure and including a first fluid supply member to provide a fluid to an interior of the enclosure. The sampling system also includes a manifold in fluid communication with the analyte sampler. A process for sampling an analyte includes subjecting the capillary tube to a negative pressure; and controlling the temperature of the capillary tube to immobilize the analyte in the capillary tube; providing an analyte to a second end of the capillary tube; and immobilizing the analyte in the capillary tube to sample the analyte.

Porous sol-gel material essentially consisting of units of one or more first polyalkoxysilanes chosen from the following compounds: (chloromethyl)triethoxysilane; 1,3-dimethyltetramethoxydisiloxane; ethyltrimethoxysilane; triethoxy(ethyl)silane; triethoxymethylsilane; triethoxy(vinyl)silane; trimethoxymethylsilane; trimethoxy(vinyl)silane; tetraethoxysilane or tetramethoxysilane (TMOS) and of units of one or more second polyalkoxysilanes chosen from the following compounds: (N-(3-(trimethoxysilyl)propyl)ethylenediamine; 3-aminopropyltriethoxysilane (APTES) and 3-aminopropyltrimethoxysilane, in a first polyalkoxysilane/second polyalkoxysilane molar ratio of 1/0.01 to 1/1, optionally comprising a probe molecule, method of preparation and applications in the trapping of monocyclic aromatic hydrocarbons and other pollutants or in their detection.

The invention relates to the quantitative measurement of steroidal compounds by mass spectrometry. In a particular aspect, the invention relates to methods for quantitative measurement of steroidal compounds from multiple samples by mass spectrometry.