Disclosed is a novel means for accurate qualitative and quantitative analyses for each N-glycosylation site. The method of analyzing N-linked sugar chain(s) of glycoprotein according to the present invention comprises: treating a part of a glycopeptide-containing sample to be analyzed with endo-β-N-acetylglucosaminidases to cleave off sugar chains while leaving one GlcNAc of the chitobiose core on the Asn at the N-glycosylation site; subjecting the obtained sugar chain-cleaved sample to preliminary liquid chromatography/mass spectrometry; predicting the retention time of the glycopeptide of interest and the mass-to-charge ratio (m/z) of the precursor ion in main analysis based on the results of the preliminary liquid chromatography/mass spectrometry; and carrying out the main analysis. By this method, the binding sites and structures of N-linked sugar chains in a glycoprotein can be analyzed. By using the sugar chain-cleaved sample as an internal standard in the main analysis, quantitative analysis of sugar chains at each glycosylation site also becomes possible.

A method and system for determining the dissociation constant (K.sub.d) of a reversible binding pair of a first compound and a second compound. The method comprises: injecting a sample into a capillary tube via one or more valves, wherein the sample comprises the first compound, the second compound, and a first compound-second compound complex; injecting a mobile phase into the capillary tube via said one or more valves, the sample flowing through the capillary tube under laminar flow conditions, wherein the second compound and the first compound-second compound complex is separated from the first compound by transverse diffusion; measuring time dependence of a signal that is proportional to the concentration of the first compound, both unbound and bound to the second compound using a measurement component; and determining the equilibrium dissociation constant based on the measured signal versus time dependence.

Reagents and methods for obtaining a metabolite solution comprising a mass spectrometry compatible volatile salt or volatile compound.

An automated system for lipid exchange-mass spectrometry, e.g., measuring affinity of a membrane protein for lipids. The automated systems herein can measure the specificity of membrane protein-lipid interactions, detect remodeling of the membrane environment, and determine optimal lipid composition for membrane proteins.

A mass spectrometry method includes detecting, in a first mass spectrometry of a sample containing a glycan having a plurality of sialic acids each modified differently, a plurality of oxonium ions derived from each of the plurality of sialic acids, and calculating relative values of intensities of the plurality of oxonium ions based on data obtained by the detection.

A system for sampling a sample material includes a probe which can have an outer probe housing with an open end. A liquid supply conduit within the housing has an outlet positioned to deliver liquid to the open end of the housing. The liquid supply conduit can be connectable to a liquid supply for delivering liquid at a first volumetric flow rate to the open end of the housing. A liquid exhaust conduit within the housing is provided for removing liquid from the open end of the housing. A liquid exhaust system can be provided for removing liquid from the liquid exhaust conduit at a second volumetric flow rate. A droplet dispenser can dispense drops of a sample or a sample-containing solvent into the open end of the housing. A sensor and a processor can be provided to monitor and maintain a liquid dome present at the open end.

A method for monitoring an analyzer including a liquid chromatography device (LC) having at least two liquid chromatography (LC) streams, the method including continuously monitoring one or more parameters in measurement data of samples in each of the at least two LC streams, the one or more parameters being independent of an analyte concentration of the respective sample, determining if the one or more monitored parameters show an expected behavior and triggering a response upon detection that the one or more monitored parameters deviate from the expected behavior.

A sample may be prepared and then analyzed using a liquid chromatography with tandem mass spectrometry system to determine presence and concentration of herbicide(s) present in the sample. In some examples, the method involves providing a sample containing one or more herbicides and adding a base to the sample. The base may increase the pH of the sample to ≥12, thereby hydrolyzing esters of the one or more herbicides. The method may further involve, subsequent to hydrolyzing the esters of the one or more herbicides, adding an acid to the sample so as to lower the pH of the sample to ≤3. Once prepared, the sample can be injected into a liquid chromatography instrument to separate the herbicide molecules from other molecules present in the sample before being ionized and characterized by mass-to-charge ratio and relative abundance using one or more mass spectrometers.

The exemplary embodiments may provide liquid chromatography systems that are smaller in size and with reduced extra-column volume than conventional liquid chromatography systems. The exemplary embodiments may reduce the size of the liquid chromatography systems enough that the liquid chromatography systems of the exemplary embodiments may be deployed adjacent to automated sample preparation robotics, adjacent to a process stream, or adjacent to the inlet of a mass spectrometer. In addition, the exemplary embodiments may reduce the extra-column volume of the liquid chromatography system by eliminating many of the connection tubes found in conventional liquid chromatography systems and by situating components of the liquid chromatography system in closer proximity.

A nucleophilic substitution reaction to crosslink cyclodextrin (CD) polymer with rigid aromatic groups, providing a high surface area, mesoporous CD-containing polymers (P-CDPs). The P-CDPs can be used for removing organic contaminants from water. By encapsulating pollutants to form well-defined host-guest complexes with complementary selectivities to activated carbon (AC) sorbents. The P-CDPs can rapidly sequester pharmaceuticals, pesticides, and other organic micropollutants, achieving equilibrium binding capacity in seconds with adsorption rate constants 15-200 times greater than ACs and nonporous CD sorbents. The CD polymer can be regenerated several times, through a room temperature washing procedure, with no loss in performance.