Group extraction

This protocol for hormone characterization is deceptively simple. Hormones are extremely potent and are produced in very small amounts. Obtaining sufficient hormone to allow its chemical characterization often involves biochemical isolations on a heroic scale. When Roger Guillemin and Andrew Schally independently purified and characterized thyrotropin-releasing hormone (TRH) from the hypothalamus, Schally s group processed about 20 tons of hypothalamus from nearly two million sheep, and Guillemin s group extracted the... 

Extensions of algebraic groups (extracted from conversation... 

Experiments on TPE extraction by dioxide from nitric acid solutions containing nitrates have shown that this reagent can be used for quantitative group extraction and concentrating of TPE from solutions containing 1-15 M HNO, and arbitrary amounts of Li, Al, Na or NH nitrates. Table 1 gives some examples of Am concentrating up to the hundredfold. 

Where A was the mean parasitaemia in the negative control and B was the parasitaemia in the test group. Extract activity was determined by percentage reduction of parasitaemia in treated groups compared with untreated infected mice. For all the groups of experimental mice used, survival time in days was recorded and the mean for each group calculated. ... 

Figure 2-27. Structure of the reaction center complex of Rps.viridis. a) Whole structure, b) Prosthetic groups extracted from the whole structure (He = heme iron complex).

Ammonium pyrrolidine dithiocarbamate (APDC), for example, is suitable for group extraction in water. It is added as a 2 % aqueous solution to the water sample, which should be set to pH 2 (5 ml to 1 litre of water sample). Repeat extraction with about 13 ml of chloroform each time until... 

In order to make the circle of trace elements detectable by group extraction as wide as possible, F. A. Pohl has described a method in which the... 

Fedotov, P.S. Maryutina, T.A. Grebneva, O.N. Kuz min, N.M. Spivakov, B.Ya. Use of countercurrent partition chromatography for the preconcentration and separation of inorganic compounds group extraction of Zr, Hf, Nb, and Ta for their subsequent determination by inductively coupled plasma atomic emission spectrometry. J. Anal. Chem. 1997,52,1034. 

UREX + 1 UREX + la U (highly purified) U (highly purified) Tc, 1 (LLFPs, dose issue) Tc, 1 (LLFPs, dose issue) Cs, Sr (short-term heat mgmt.) Cs, Sr (short-term heat mgmt.) Other FPs FPs (including lanthanides) TRU + Ln (Temporary storage) TRU (group extraction) ... 

Complexation in extraction systems has been the subject of extensive research. The results obtained helped to establish the mechanisms of many extraction processes, to predict the type of compounds that must be formed in the system, and to evaluate the conditions for selective or group extraction. This review concentrates primarily on results obtained in our laboratories in Moscow. 

Rabinowitz, J.C., and Snell, E.E., 1947. Vitamin Bg group. Extraction procedures for the microbiological determination of vitamin Bg. Analytical Chemistry. 19 277-280. 

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