Abstract: Provided are methods of detecting the presence or amount of a vitamin D metabolite in a sample using mass spectrometry. The methods generally comprise ionizing a vitamin 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. Also provided are methods to detect the presence or amount of two or more vitamin D metabolites in a single assay.

Abstract: The invention provides methods and apparatuses that utilize mass spectrometry for preparation of a surface to have catalytic activity through molecular soft-landing of mass selected ions. Mass spectrometry is used to generate combinations of atoms in a particular geometrical arrangement, and ion soft-landing selects this molecular entity or combination of entities and gently deposits the entity or combination intact onto a surface.

Abstract: The invention relates to the use of molecular tweezers as sensitive materials in chemical sensors intended to detect or assay organic compounds in the vapour state, and in particular nitro compounds. These molecular tweezers correspond to the general formula (I): in which: MC1 and MC2 represent macrocycles; p and q are equal to 0 or 1; X and Y are optionally substituted C1 to C10 alkylene groups; while E represents an optionally substituted cyclic or heterocyclic spacer group; and in which MC1 and MC2 are positioned facing each other. Fields of application: detection of explosives, control and monitoring of atmospheric pollution and of the quality of ambient air in relatively confined spaces, and monitoring of industrial sites.

Abstract: 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.

Abstract: An optical gas concentration sensor and method for measuring blood gas based on the light adsorption sensing technique are disclosed. The optical gas concentration sensor comprises a light source, a photo detector, and a gas filtering membrane for separating the indicator and a liquid. A gas in the liquid diffuses to the indicator through the gas filtering membrane so as to change the color of the indicator due to the chemical reaction occurred between the indicator and the gas. Then, the photo detector receives the light passing though the reacted indicator from the light source. The gas concentration is determined based on pH-sensitive absorbance spectrum of the indicator.