Effect of synergistic extraction

Synergism It may be defined as the process whereby two different reagents when employed together are capable of extracting a metal ion with a distinct and marked efficiency, in comparison to a condition when the same two reagents are used individually . 

It has been observed that the complex formed by Mn2+ with dithizone alone is of no practical analytical utility because of the fact that it undergoes decomposition very quickly. However, the addition of a base, such as pyridine into the Mn2+ plus dithizone complex yields a red-complex, which is fairly stable to oxidation and light and, therefore, forms the basis for a very sensitive photometric method employed in estimating trace amounts of Mn2+. 

Equation Following is the chemical reaction of the above complex formation  

Noticeably, the reaction of Ni2+ with dithizone is quite slow and sluggish. Nevertheless, this slow reaction is significantly accelerated by the addition of nitrogen-containing bases like 1, 10-phenanthroline. The resulting complex may be represented by the following equation  

It is the basis of a very sensitive synergistic extraction photometric procedure for trace amounts of 

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Hi) Effect of ion-pair formation, and (/v) Effect of synergistic extraction... 

Nayak, S. S. Ghosh, A. K. Debnath, B. Vishnoi, S. P. Jha, T., Synergistic effect of methanol extract of Abies webbiana leaves on sleeping time induced by standard sedatives in mice and antiinflammatory activity of extracts in rats, J. Ethnopharmacol., 2004, 93, 397-402. 

HraS, A.R., Hadolin, M., Knez, Z. and Bauman, D. Comparison of antioxidative and synergistic effects of rosemary extract wit a-tocopherol, ascorbyl pahnitate and citric acid in sunflower oil. Food Chem. 71, 229-233 (2000). 

The synergistic effect of DPP on the extraction of Ni(II) with dithizone was also studied and confirmed the formation of an interfacial complex [24]. 

Vfe noticed that stepwise purification of the crude extracts resulted in gradually diminishing activity. When several of the identified phenolic compounds were individually tested, none of them exhibited biological activity. Wfe concluded that the biological activity was associated with either the threshold levels of chemicals in the crude extracts or synergistic effect of sane chemicals. Similar observations were made by others, and it needs to be verified by further experimentation (17, 48). 

Water-soluble nickel salts enter the cells with relative ease but are less effective than crystalline particulates in the cell transformation assay, when using hamster cells [429, 430]. However, an enhancement of viral transformation of cells has been found [431, 432], In addition, a synergistic effect of cigarette smoke extracts, benzo[a]pyrene and nickel sulphate on the morphological transformation of hamster embryo cells has also been obtained [433], It was suggested that nickel salts are more potent as promoters than they are as initiators [434],... 

Botanical raw materials and their extracts therefore usually contain complex mixtures of several chemical constituents. For a large majority of botanical plant material and extracts of these used as dietary supplements, it is not known with certainty which of the various components is responsible for the purported pharmacological effect. It is generally believed that several constituents act synergistically to provide the purported effect. In actual practice, two or more of the chemical constituents present in the plant material are identified as marker compounds that are characteristic of the plant material to be tested, for identification and monitoring of the stability of the extracts. 

However, even this simplified formula does not justify the use of the ratio of stability constants of the extracted complexes as the only measure of selectivity of extractive separations. Such a widely used approach is obviously based on an implicit assumption that the partition constants of neutral complexes ML of similar metal ions are similar, so that their ratio should be close to unity. This is, however, an oversimplification because we have shown that the ifoM values significantly differ even in a series of coordi-natively saturated complexes of similar metals [92,93]. Still stronger differences in the values have been observed in the series of lanthanide acetylacetonates, due to different inner-sphere hydration of the complexes (shown earlier), but in this case, self-adduct formation acts in the opposite direction [100,101] and partly compensates the effect of the differences in. Tdm on S T(see also Fig. 4.15). Such compensation should also be observed in extraction systems containing coordinatively unsaturated complexes and a neutral lipophilic coextractant (synergist). 

Bioallethrin is a synthetic pyrethrin insecticide. Piperonylbutoxide, a weak insecticide itself, has synergistic activity. The same holds true for the combination of pyrethrum extract with piperonylbutoxide. These combinations have the same efficacy as permethrin. Local irritation occurs frequently effect and contact with mucous membranes and the eyes must be avoided. 

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