Provided are methods of detecting the presence or amount of a vitamin D metabolite in a sample using mass spectrometry. The methods generally directed to 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.

A method of passively detecting radiofrequency (RF) signals spontaneously emitted by a non-equilibrium population of electrons that are spin polarized by flowing through a chiral media during relaxation of the spin polarized electrons to equilibrium at a frequency corresponding to a Zeeman spin-flip energy of the spin polarized electrons under influence of a magnetic field (MF). The MF is applied to the chiral media for a predefined time period to shift a frequency and magnitude of the spontaneously emitted RF signals in line with Zeeman effect. The shifted emitted RF signals is passively detected and stored for medical use applications using a receiver antenna tuned to a resonant frequency of the shifted emitted RF signals.

Provided are methods for determining the amount of thyroglobulin in a sample using various purification steps followed by mass spectrometry. The methods generally involve purifying thyroglobulin in a test sample, digesting thyroglobulin to form peptide T129, purifying peptide T129, ionizing peptide T129, detecting the amount of peptide T129 ion generated, and relating the amount of peptide T129 ion to the amount of thyroglobulin originally present in the sample.

The invention generally relates to systems and methods for quantifying an analyte extracted from a sample. In certain embodiments, the invention provides methods that involve introducing a solvent into a capillary, introducing the capillary into a vessel including a sample such that a portion of the sample is introduced into the capillary, moving the sample and the solvent within the capillary to induce circulation within the sample and the solvent, thereby causing the analyte to be extracted from the sample and into the solvent, analyzing the analyte that has been extracted from the sample, and quantifying the analyte. In certain embodiments, the quantifying step is performed without knowledge of a volume of the sample and/or solvent.

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 thyroglobulin in a sample using various purification steps followed by mass spectrometry. The methods generally involve purifying thyroglobulin in a test sample, digesting thyroglobulin to form peptide T129, purifying peptide T129, ionizing peptide T129, detecting the amount of peptide T129 ion generated, and relating the amount of peptide T129 ion to the amount of thyroglobulin originally present in the sample.

The use of volatilization reagents is disclosed for improved detection of inorganic oxidizers such as, but not limited to, chlorates and perchlorates. Detection methods are disclosed whereby a reagent can transfer a proton to the anion (i.e., chlorate, perchlorate, etc.) of an inorganic salt analyte, forming an acid (i.e., chloric acid, perchloric acid) that is easier to detect by a mechanism whereby the acidified reagent is more easily vaporized, and hence, more easily detected. Concurrently, the anion of the acid forms a new salt with the cation released from the salt that was acidified. The reagents can also include acidic salts or cation-donators, more generally. In some embodiments, hydrated reagents or co-reagents that can release water can be employed.

Methods are described for measuring the amount of one or more of vitamin A, α-tocopherol, and the combination of β-tocopherol and γ-tocopherol in a sample. More specifically, mass spectrometric methods are described for detecting and quantifying one or more of vitamin A, α-tocopherol, and the combination of β-tocopherol and γ-tocopherol in a sample.

The present invention relates to a metabolic biomarker set for use in assessing breast cancer in a mammalian subject. In particular, the invention relates to a metabolic biomarker set for screening and/or diagnosing breast cancer, the metabolic biomarker set including at least (a) one amino acid selected from glutamine, glutamate and serine, and one lipid, or (b) glutamine and glutamate. Further, the invention relates to a metabolic biomarker set for prediction of therapeutic response to breast cancer neoadjuvant chemotherapy. Moreover, the present invention relates to a method for assessing breast cancer, which includes obtaining a biological sample, preferably blood, from a mammalian subject and measuring in the biological sample the amount and/or ratios of metabolites. By employing the specific biomarkers and the method according to the present invention it becomes possible to more properly and reliably assess breast cancer.

Methods are described for measuring the amount of one or more of vitamin A, α-tocopherol, and the combination of β-tocopherol and γ-tocopherol in a sample. More specifically, mass spectrometric methods are described for detecting and quantifying one or more of vitamin A, α-tocopherol, and the combination of β-tocopherol and γ-tocopherol in a sample.