Infusions, analysis

Alessandrino R Bemasconi R Caldera D, et al. Adverse events occurring during bone marrow or peripheral blood progenitor cell infusion analysis of 126 cases. Bone Marrow Transpl 1999 23 533-537. 

Fourier transform ion-cyclotron (FT-ICR-MS) provides the highest mass resolution and accuracy, and enables the determination of the elemental compositions of metabolites, which facilitates annotation procedures for unknown compounds (95). Direct infusion analysis of plant extract without a previous separation and/or derivatization can be achieved however, its use is very restricted due to the equipment cost, the difficulties in hardware handling, and the extremely large amount of data generated. Takahashi et al. applied this technique to elucidate the effects of the overexpression of the YK1 gene in stress-tolerant GM rice (96). More than 850 metabolites could be determined, and the metabolomics fingerprint in callus, leaf, and panicle was significantly different from one another. 

Rahn and Konig (1978) recalled previous findings suggesting that phenols and other moderately acidic organic components could be responsible for the frequently observed nauseous symptoms of sensitive coffee drinkers. It was not known whether there is a specific component that is responsible for nausea. This was why they analyzed an ether extract of a coffee infusion, analysis of which allowed the identification of three new coffee constituents 3-methyl- (H.26), 4-ethyl- (H.29) 1,2-benzenediols and... 

The very first microfluidic-MS applications have involved sample infusion analysis from chips with a flat spraying surface or with inserted ESI capillary emitters. These relatively simple devices were fabricated from glass or polymeric substrates and were interfaced to IT, TOP, or hybrid Q-TOF instruments, and sample infusion was accomplished by connecting syringe pumps, N2 cylinders, or external EOF pumping capillaries to the chip. Alternatively, infusion experiments have... 

Kanny, K., Mohan, T.P., 2014. Resin infusion analysis of nanoclay filled glass fiber laminates. Composites Part B Engineering 58, 328—334. 

In most of the studies discussed above, except for the meta-linked diamines, when the aromatic content (dianhydride and diamine chain extender), of the copolymers were increased above a certain level, the materials became insoluble and infusible 153, i79, lsi) solution to this problem with minimum sacrifice in the thermal properties of the products has been the synthesis of siloxane-amide-imides183). In this approach pyromellitic acid chloride has been utilized instead of PMDA or BTDA and the copolymers were synthesized in two steps. The first step, which involved the formation of (siloxane-amide-amic acid) intermediate was conducted at low temperatures (0-25 °C) in THF/DMAC solution. After purification of this intermediate thin films were cast on stainless steel or glass plates and imidization was obtained in high temperature ovens between 100 and 300 °C following a similar procedure that was discussed for siloxane-imide copolymers. Copolymers obtained showed good solubility in various polar solvents. DSC studies indicated the formation of two-phase morphologies. Thermogravimetric analysis showed that the thermal stability of these siloxane-amide-imide systems were comparable to those of siloxane-imide copolymers 183>. 

Figure 5.58 Reconstructed LC-MS-MS ion chromatograms for selected-reaction monitoring of methoxyfenozide using the m/z 367 to m/z 149 transition from the continual post-column infusion of a standard solution of analyte during the HPLC analysis of a...

In the previous discussion of the one- and two-compartment models we have loaded the system with a single-dose D at time zero, and subsequently we observed its transient response until a steady state was reached. It has been shown that an analysis of the response in the central plasma compartment allows to estimate the transfer constants of the system. Once the transfer constants have been established, it is possible to study the behaviour of the model with different types of input functions. The case when the input is delivered at a constant rate during a certain time interval is of special importance. It applies when a drug is delivered by continuous intravenous infusion. We assume that an amount Z) of a drug is delivered during the time of infusion x at a constant rate (Fig. 39.10). The first part of the mass balance differential equation for this one-compartment open system, for times t between 0 and x, is given by ... 

InsAument parameters (sheath and auxiliary gas flows, spray voltage, capillary temperature, collision cell gas flow and offset, etc.) should be optimized while infusing a standard of tebuconazole prior to the Arst attempt at analysis. Optimization should be performed at an HPLC Aow rate and composition simulating those present during elution of tebuconazole using each HPLC condition set employed... 

Subsequently 36 strains of aerobic endospore-forming bacteria, consisting of six Bacillus species and one Brevibacillus species could be discriminated using cluster analysis of ESMS spectra acquired in the positive ion mode (m/z 200-2000).57 The analysis was carried out on harvested, washed bacterial cells suspended in aqueous acidic acetonitrile. The cell suspensions were infused directly into the ionization chamber of the mass spectrometer (LCT, Micromass) using a syringe pump. Replicates of the experiment were performed over a period of six months to randomize variations in the measurements due to possible confounding factors such as instrumental drift. Principal components analysis (PCA) was used to reduce the dimensionality of the data, fol-... 

Castrillo, J. L. Hayes, A. Mohammed, S. Gaskell, S. J. Oliver, S. G. An optimized protocol for metabolome analysis in yeast using direct infusion electrospray mass spectrometry. Phytochemistry 2003, 62, 929-937. 

To summarise, a fractionation step allows the isolation of the compounds of interest from the other molecular constituents, particularly from the fatty acids that are well-ionised. To compensate for the low ionisation yield of some compounds, such as TAGs, the solutions may be doped with a cation. Samples are then directly infused into the ion electrospray source of the mass spectrometer. A first spectrum provides an overview of the main molecular compounds present in the solution based on the peaks related to molecular cations. The MS/MS experiment is then performed to elucidate the structure of each high molecular compound. Table 4.2 shows the different methods of sample preparation and analysis of nonvolatile compounds as esters and TAGs from reference beeswax, animal fats and archaeological samples. 

Tandem mass spectrometric methods have demonstrated superb specificity because of their ability to isolate analytes selectively in the presence of endogenous interferences. Attempts to further increase sample throughput led to the idea of using LC/MS/MS without the LC. Traditional chromatographic separations were replaced with flow injection analysis (FLA) or nanoelectrospray infusion techniques. The MS-based columnless methods attracted a lot of attention because of their inherent fast cycle times and no need for LC method development. 

Cassette analysis (performed by user) Mix samples, injected to same LC-MS or infused to MS... 

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