Sources and Uses

The hybrid has other advantages of sensitivity, low signal-to-noise ratio, fast switching between MS and MS/MS modes, use with continuous or pulsed ion sources, and use with high- or low-energy collision-induced ion decomposition. 

Generally, soluble materials are more effective as micronutrient sources than are insoluble ones. For this reason, many soil minerals that contain the micronutrient elements are ineffective sources for plants. Some principal micronutrient sources and uses are summarized below. In this discussion the term frits refers to a fused, pulverized siUceous material manufactured and marketed commercially for incorporation in fertilizers. Chelates refers to metaHoorganic complexes specially prepared and marketed as especially soluble, highly assimilable sources of micronutrient elements (see CHELATING agents). 

T. A. Hase, JJmpoled Synthons, A Survey of Sources and Uses in Synthesis ]ohxi Wiley Sons, Inc., New York, 1987. 

During this period of intense synthetic research, a search for inexpensive raw materials for the partial synthesis of steroids was initiated. Abundant quantities of the sapogenin diosgenin [512-04-9] were isolated from plant sources and used for the industrial preparation of steroids (9). 

Source and use of data within recursive modelling procedure Examples of variable names shown in ITALICS ... 

Inorganic chemicals are derived from minerals in the ground or from the air, not from living matter. Some idea about the importance of this branch of the chemical industry is illustrated by reviewing the ten largest production volume chemicals, their sources, and uses. 

In reduced-flow LC-MS systems, the solvent flow into the spectrometer is reduced to a level where the pumping system can cope. Essentially, three such systems have been developed direct-liquid-introduction (DLI), flowing FAB [531] and electrospray [532]. An alternative approach to belt transport interfacing is to deliver the column eluate directly into the MS source and use Cl techniques. Methods based on this principle are called direct-liquid-injection systems, which are comprised of capillary flow restrictors, diaphragms,... 

Reagents were purchased from commercial sources and used without further purification. Product identities were confirmed by comparison of HPLC retention times with authentic samples. The Pd/C catalyst was purchased as a dry, edge-coated, unreduced catalyst with 5 wt% in Pd. HPLC analyses were performed on a HP 1090 (stationary phase C18, 25 cm x 0.46 cm mobile phase CH3CN/H20 1% H3P04, 90% H20 to 100% CH3CN gradient over 25 min, 1 ml/min flow, UV-Vis detection). For safety aspects of handling Pd/C, see ref. 7.7... 

Rainbow trout (100-250 g) were purchased from Roaring River fish hatchery, Scio, Oregon and held under conditions previously described (11). Chlorobenzene (MCB) and carbon tetrachloride (CCI4) were obtained from commercial sources and used without further purification. Chlorobenzene was dissolved in an equal volume of com oil and administered as a single intra-peritoneal (i.p.) injection (either 0.5 or 1.0 ml/kg). Control animals received a similar volume of corn oil. Carbon tetrachloride was given undiluted by i.p. injection (0.2, 1.0, or 2.0 ml/kg) and control animals received a similar volume of physiological saline. 

However, if those natural products have been previously synthesised one may start from them, provided that it simplifies the synthesis, since repetitions and waste of time should be avoided. Moreover, once a key intermediate has been synthesised, but may also be obtained easily by degradation from some other product, including the same natural product that is being synthesised, the chemist should resort to such a source and use it to continue the synthesis. This approach to total synthesis is referred to as the relay approach. 

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