Disclosed herein are systems for imaging and ablating a sample. An imaging/ablating device includes an optical assembly, a sample stage, and a receiver. The optical assembly enables ablation of a region of interest within the sample. The laser light propagated from the optical assembly during ablation propagates substantially in the same direction as the direction of travel of the ablation plume toward the receiver. A laser focus detection unit including at least one reference laser and photodetector generates at least one real-time detection signal indicative of one or more characteristics of the sample during ablation and/or of a distance from the objective to the sample stage or a surface of the sample. A controller coupled with the laser focus detection unit dynamically controls in real-time one or more parameters of the ablation laser and/or a position of the objective and/or a position of the receiver relative to the sample to improve MS imaging quality.

The present disclosure discusses a method of separating and/or purifying acidic peptides by the use of a mobile phase having a pH greater than or about equal to the isoelectric point of one or more of the metal oxides in the flow path.

Methods for determining the relative abundance of viral capsid components in a sample of viral particles are disclosed. In embodiments, methods for determining the relative abundance of empty capsids, partially-full capsids and full capsids (e.g., containing a heterologous nucleic acid molecule) of adeno-associated virus are disclosed.

Systems and methods are provided for microbial identification using cleavable tags. Control information is sent to a mass spectrometer to fragment one or more nucleic acid primers labeled with a first tag and monitor for an intensity of the first tag in a mass spectrometry (MS) method. An ion source provides a beam of ions from a polymerase chain reaction amplified sample that includes one or more nucleic acid primers labeled with the first tag. The first tag binds to one or more nucleic acid primers of a known microbe and is cleaved from the nucleic acid primers during the MS method. The mass spectrometer receives the beam of ions and is adapted to perform the MS method on the beam of ions. If the intensity of the first tag received from the mass spectrometer exceeds a threshold value, the known microbe is identified in the sample.

Disclosed herein are embodiments of methods for oligonucleotide analysis using a novel solid-phase extraction and hydrophilic-interaction liquid chromatography. The unique polar-based retention methods provided herein provide a high-recovery extraction. The methods improve assay reliability and reproducibility and reach picomolar sensitivity with the demonstrably beneficial accurate mass platform. Also disclosed herein are systems and computer program products for performing these methods.

Embodiments of the invention relate to the use of a melatonin agonist in the treatment of free running circadian rhythms in patients, including light perception impaired patients, e.g., blind patients, and to methods of measuring circadian rhythm.

A multi-dimensional liquid analysis system includes a flow splitter for separating mobile phase outflow from a first dimension liquid analysis system into first and second liquid split outlet flows. Volumetric flow rate control of the split outlet flows is provided by a flow control pump which withdraws one of the split outlet flows from the flow splitter at a controlled withdrawal flow rate to define the other split outlet flow rate as the difference between the outflow rate from the first dimension system and the withdrawal flow rate. In this manner, accurate and consistent flow division can be accomplished, which is particularly useful for multi-dimensional liquid analysis.

The present invention generally pertains to methods of characterizing charge variants of a protein of interest. In particular, the present invention pertains to the use of desalting size exclusion chromatography-reduced peptide mapping mass spectrometry to identify charge variants separated by capillary isoelectric focusing.

A method for determining in a sample, by mass spectrometry, the amount of one or more analytes selected from the group consisting of 12,13-DiHOME, 3-hydroxybutyrate (BHBA), 3-hydroxyoctanoate, 3-methylglutarylcarnitine, 3-ureidopropionate, 7-alpha-hydroxy-4-cholesten-3-one (7-Hoca), citrate, fucose, fumarate, gamma-tocopherol, glutamate, glutarate, glycerol, glycochenodeoxycholate, glycocholate, hypoxanthine, maleate, malonate, mannose, orotate, 2,3-pyrdinedicarboxylate, ribose, serine, taurine, taurochenodeoxycholate, taurocholate, palmitoleate, linolenate, xanthine, xylitol, and combinations thereof is described. The method comprises subjecting the sample to an ionization source under conditions suitable to produce one or more ions detectable by mass spectrometry from each of the one or more analytes; measuring, by mass spectrometry, the amount of the one or more ions from each of the one or more analytes; and using the measured amount to determine the amount of each of the one or more analytes in the sample.

Methods and system for identification of dimer species using online chromatography and electrospray ionization mass spectrometry are provided. Also provided are methods and system for quantitation of heterodimer species using immunoprecipitation and liquid chromatography-mass spectrometry.