Stable extraction

Exposure time can be chosen arbitrarily or the time to equilibrium can be used. Time to equilibrium is determined by extracting for incremental times until a stable extracted concentration is achieved. It is imperative that the selected exposure time be used exactly and consistently for any measurements that are to be compared. 

From such studies, it can be expected that progress will be made toward the prevention of extractant degradation and the design of more stable extractants. 

Key Words Cell-free protein synthesis stable extract from wheat embryos NMR ubiquitin. 

Aroma/flavor recovery Hop Spices Roses Stable extract Partialy fractionated product form Production unit Production unit... 

Radio- Half-life Cosmogenic Stable Extracted Background Overall... 

PGA Fomiation with Cell-Free Enj me Frepaiatioiis. The first successful attempt to obtain COt fixation in PGA was that of Fager (108), who found that spinach chloroplast preparations would form labeled PGA from C <3s provided they were supplemented with a heat-stable extract of spinach leaves or algae. A mixture of ribulose... 

Two molecules of vitamin A are formed from one molecule of -carotene. Vitamin A crystallizes in pale yellow needles m.p. 64 C. It is optically inactive. It is unstable in solution when heated in air, but comparatively stable without aeration. Vitamin A is manufactured by extraction from fish-liver oils and by synthesis from / -ionone. The role of vitamin A in vision seems to be different from its systemic function. See also relincne and rhodopsin. 

The hydration of more inert ions has been studied by O labelling mass spectrometry. 0-emiched water is used, and an equilibrium between the solvent and the hydration around the central ion is first attained, after which the cation is extracted rapidly and analysed. The method essentially reveals the number of oxygen atoms that exchange slowly on the timescale of the extraction, and has been used to establish the existence of the stable [1 10304] cluster in aqueous solution. 

The following are examples of the above procedure. A mixture of diethylamine and re-butyl alcohol may be separated by adding sufficient dilute sulphuric acid to neutralise the base steam distillation will remove the alcohol. The amine can be recovered by adding sodium hydroxide to the residue and repeating the distillation. A mixture of diethyl ketone and acetic acid may be treated with sufficient dilute sodium hydroxide solution to transform the acid into sodium acetate and distilling the aqueous mixture. The ketone will pass over in the steam and the non-volatile, stable salt will remain in the flask. Acidification with dilute sulphuric acid hberates acetic acid, which can be isolated by steam distillation or by extraction. 

Thermal Stability. At processing temperatures in both the extraction and recovery plants the solvent should be completely stable to avoid expensive solvent losses contamination of the solvent by any solvent breakdown products must be avoided. 

Phenolphthalein. Alophen, Ex-Lax, Feen-a-Miat, Modane, and Phenolax are trade names for phenolphthaleia [77-09-8] (3,3-bis(4-hydroxyphen5l)-l-(3ff)-l isobensofuranone) (10). It is a white or faintiy yellowish white crystalline powder, odorless and stable ia air, and practically iasoluble ia water one gram is soluble ia 15 mL alcohol and 100 mL diethyl ether. Phenolphthaleia may be prepared by mixing phenol, phthaHc anhydride, and sulfuric acid, and heating at 120°C for 10—12 h. The product is extracted with boiling water, then the residue dissolved ia dilute sodium hydroxide solution, filtered, and precipitated with acid. 

Borane—dimethyl sulfide complex (BMS) (2) is free of these inconveniences. The complex is a pure 1 1 adduct, ca 10 Af in BH, stable indefinitely at room temperature and soluble in ethers, dichioromethane, benzene, and other solvents (56,57). Its disadvantage is the unpleasant smell of dimethyl sulfide, which is volatile and water insoluble. Borane—1,4-thioxane complex (3), which is also a pure 1 1 adduct, ca 8 Af in BH, shows solubiUty characteristics similar to BMS (58). 1,4-Thioxane [15980-15-1] is slightly soluble in water and can be separated from the hydroboration products by extraction into water. 

Rya.nia., The root and stem of the plant yania speciosa family Flacourtiaceae, native to South America, contain from 0.16—0.2% of iasecticidal components, the most important of which is the alkaloid ryanodine [15662-33-9] C25H250 N (8) (mp 219—220°C). This compound is effective as both a contact and a stomach poison. Ryanodine is soluble ia water, methyl alcohol, and most organic solvents but not ia petroleum oils. It is more stable to the action of air and light than pyrethmm or rotenone and has considerable residual action. Ryania has an oral LD q to the rat of 750 mg/kg. The material has shown considerable promise ia the control of the European com borer and codling moth and is used as a wettable powder of ground stems or as a methanohc extract. Ryanodine uncouples the ATP—ADP actomyosia cycle of striated muscle. 

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