Solvents carriers

In many applications in mass spectrometry (MS), the sample to be analyzed is present as a solution in a solvent, such as methanol or acetonitrile, or an aqueous one, as with body fluids. The solution may be an effluent from a liquid chromatography (LC) column. In any case, a solution flows into the front end of a mass spectrometer, but before it can provide a mass spectrum, the bulk of the solvent must be removed without losing the sample (solute). If the solvent is not removed, then its vaporization as it enters the ion source would produce a large increase in pressure and stop the spectrometer from working. At the same time that the solvent is removed, the dissolved sample must be retained so that its mass spectrum can be measured. There are several means of effecting this differentiation between carrier solvent and the solute of interest, and thermospray is just one of them. Plasmaspray is a variant of thermospray in which the basic method of solvent removal is the same, but the number of ions obtained is enhanced (see below). 

The successful employment of any insecticide depends on its proper formulation into a preparation that can be appHed for insect control with safety to the apphcator, animals, and plants. Insecticides are commonly formulated as dusts, water dispersions, emulsions, and solutions. The preparation and use of such formulations involves accessory agents such as dust carriers, solvents, emulsifiers, wetting and dispersing agents, stickers, and deodorants or masking agents (1). 

Laminates. Laminate manufacture involves the impregnation of a web with a Hquid phenoHc resin in a dip-coating operation. Solvent type, resin concentration, and viscosity determine the degree of fiber penetration. The treated web is dried in an oven and the resin cures, sometimes to the B-stage (semicured). Final resin content is between 30 and 70%. The dry sheet is cut and stacked, ready for lamination. In the curing step, multilayers of laminate are stacked or laid up in a press and cured at 150—175°C for several hours. The resins are generally low molecular weight resoles, which have been neutralized with the salt removed. Common carrier solvents for the varnish include acetone, alcohol, and toluene. Alkylated phenols such as cresols improve flexibiUty and moisture resistance in the fused products. 

With the increasing emphasis on energy conservation and environmental considerations, additives for fuels that can correct combustion-related problems have aroused considerable interest. Many commercial fuel additives are combinations of organometaHics, dispersants, emulsifiers, and carrier solvents. The organometaHic, often a metal soap, acts as a combustion catalyst, increasing efficiency with reduction of smoke, deposits, and corrosion. 

The mbber is then separated from its solvent by steam stripping. The viscous cement is pumped into a violently agitated vessel partly full of boiling water. The hexane flashes off and, together with water vapor, passes overhead to a condenser and to a decanter for recovery and reuse after drying. Residual unpolymerized ethylene and propylene appear at the hexane condenser as noncondensibles, and are recovered for reuse after drying. The polymer, freed from its carrier solvent, falls into the water in the form of cmmb. 

FIG. 16-30 Operational steps in displacement chromatography, The column, initially equilibrated with a carrier solvent at time 0, is loaded with feed until time tp and supplied with displacer for a time to + tp. Development of the displacement train occurs during the time to and elution of the separated products ends at time tp. tp is the time required to remove the displacer from the column and restore the initial conditions, Components are niimhered in order of decreasing affinity for the stationary phase, [Reference Horoath et at, J, Ghromatogr, 2i8, 365 (1981). Reprinted with peimission of], Ghromatogr,]... 

A pair of amino acids is separated in a column in which the stationary phase is saturated with water and the carrier solvent is methanol, CH,OH. The more polar the acid, the more strongly it is adsorbed by the stationary phase. The amino acids that were separated in this column are (a) HOOCCHNH2CH,COOH and (b) HOOCCHNH2CH(CH,)2. Which amino acid would you expect to be eluted first Explain your reasoning. Refer to Major Technique 4 on chromatography, which follows these exercises. 

Raybum JR, DeYoimg DJ, Bantle JA. 1991. Altered developmental toxicity caused by three carrier solvents. J Appl Toxicol 11 253-260. 

The carrier fluid was deionized water containing 1 gm/l of Aerosol OT and 1 g/l sodiiom nitrate. Compared to the use of potassium nitrate as electrolyte, suggested by Coll et al. (lO), the carrier solvent used in this investigation has much better clarity and at room temperature has no tendency to precipitate the surfactant. ... 

Accordingly GPC analysis of dried latex samples were carried out. The carrier solvent was tetrahydrofuran and peaks were monitored by a Waters dual absorbance detector at wavelengths of 2 h and 3U0 nm. The latter detection was the closest to 350 nm available. 

A corrosion inhibitor with excellent film-forming and film-persistency characteristics is produced by first reacting Cig unsaturated fatty acids with maleic anhydride or fumaiic acid to produce the fatty acid Diels-Alder adduct or the fatty acid-ene reaction product [31]. This reaction product is further reacted in a condensation or hydrolyzation reaction with a polyalcohol to form an acid-anhydride ester corrosion inhibitor. The ester may be reacted with amines, metal hydroxides, metal oxides, ammonia, and combinations thereof to neutralize the ester. Surfactants may be added to tailor the inhibitor formulation to meet the specific needs of the user, that is, the corrosion inhibitor may be formulated to produce an oil-soluble, highly water-dispersible corrosion inhibitor or an oil-dispersible, water-soluble corrosion inhibitor. Suitable carrier solvents may be used as needed to disperse the corrosion inhibitor formulation. 

First treatment DMSO (carrier solvent for B-PatA and PatA) added at equal volume to PatA... 

Munition grade agents typically consist of at least one malodorant agent (10-90%) and an odor intensifier (0.5-5%) dissolved in a liquid carrier. Solvents include volatile hydrocarbons, plant/vegetable oils, and water. Solvents typically pose minimal toxic hazards themselves. Compositions are typically colorless to yellow liquids. As the agent ages and decomposes it may discolor and become brown. 

If you ve used a carrier solvent, then evaporate or distill it off, whichever is appropriate. Then you ll have your clean, dry product. 

Third, for each substance (or article) that is mixed with a carrier (solvent or other medium) 1) the uniformity or concentration shall be determined, 2) the solubility shall be determined (EPA only), and 3) the stability in the mixture shall be determined. Expiration dates shall be clearly shown and (EPA only) the device used to formulate the mixture shall not interfere with the integrity of the test. 

The Council and the Commission must adopt positive fists of additives, authorised to the exclusion of all others, fists of foods in which the additives may be used with conditions of use, and rules on carrier solvents. The Standing Committee on Foodstuffs must approve adoption of purity criteria for listed additives and, if necessary, methods of analysis to verily these purity criteria, sampling procedures and methods of analysis for food additives in food. The directive includes provisions that a member state may temporarily suspend or restrict application of an authorisation if it has detailed grounds for considering that the use of the additive in food, although permitted, endangers health. The... 

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