Modifier concentration, effect extraction efficiency

TABLE IV Effect of Modifier Concentration on Extraction Efficiencies for Shale Rock Using On-Line SFE/GC... 

Determination, offline GC-FID recoveries 70 to 100% PHCs the presence of the polar modifier improved the extraction of the aromatic fraction higher concentration of modifier decreases the extraction efficiency effect of the low and high MW-PAHs... 

PTRs have received considerable attention as effective agents to facilitate the use of hydrogen peroxide, but require many parameters to be adjusted to obtain good selectivity. Among them are the nature and concentration of the PTRs, where in general, the length of the alkyl groups determines the extraction efficiency, the solvent, the pH of the aqueous phase, and the presence of salts like NaCl, which modifies the distribution of the species [154]. 

Extraction properties, including efficiency, selectivity, water coextraction, and temperature dependence, are strongly affected by the properties of the extracting medium. These depend on the amine concentration and on the diluent used. In a nonpolar solvent, charged species such as ion pairs tend to stabilize by aggregation. Polar and particularly protic solvents solubilize ion pairs, reduce their aggregation, and substantially enhance their extraction efficiency. The effects of diluents are in many cases so strong that they are frequently refered to as extractant modifiers or enhancers. 

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