Biological extractive

Demeter J, Heyndrickx A. 1979. Selection of a high-performance liquid chromatographic cleanup procedure for the determination of organochlorine pesticides in fatty biological extracts. Vet Hum Toxicol 21 151-155. 

Emenhiser, C. et al.. Separation of geometrical carotenoid isomers in biological extracts using a polymeric Cjq column in reversed-phase liquid chromatography, J. Agric. Food Chem., 44, 3887, 1996. 

Biological extractions are carried out to determine if biologically important elements are at levels that are sufficient, yet not toxic, for plant needs. Acid soil extraction to determine the biologically available plant nutrients is the most common type of extraction of soil carried out. The objective is to extract a portion, not all, of a particular nutrient or metal that is correlated to the amount available to plants. The plants of primary interest are crop plants such... 

It has been noted [13, 33] that in several early publications describing total screening of biological extracts for peptide material insufficient care has been taken to avoid the ex vivo (or post mortem) formation of peptides in the extract where all proteases of the initial sample are released from the cellular compartments and are free to contact with the endogenous protein and peptide components. The resultant products with sometimes quite interesting activities should be formally considered... 

By the flrst century a.d. it was clear to both physician and protopharmacologist alike that there was much variation to be found from one biological extract to another, even when these were prepared by the same individual. It was reasoned that to fashion a rational and reproducible system of therapeutics and to study pharmacological activity one had to obtain standardized and uniform medicinal agents. 

The same principle as described above can be used for the estimation of the carotenoid content of extracts of food colorants, pharmaceuticals, foods, biological samples, or chromatographic fractions. This procedure employs calculations used for individual carotenoids of high purity and thus will estimate the total carotenoids present in a food or biological extract, where a mixture of carotenoids would be expected. Greater accuracy can be obtained as extracts are purified to contain single components (see Commentary). A spectrum scan is not employed in this procedure as the fine structure of a mix of carotenoids can only be identified after HPLC separation (see Commentary). 

Gel permeation chromatography (GPC), also called size-exclusion chromatography, is the most widely used cleanup technique for pesticides in fatty foods. It is the method of choice for rapid cleanup of biological extracts, especially from high-fat samples, to determine pesticide residues, since separation occurs on the basis of molecular size (7). 

The formation of highly UV-absorbing derivatives of estrogens with azobenzene-4-sulfonyl chloride [29] has been examined for analysis in biological extracts. The derivatives are separated by TLC arid are quantitated by direct densitometry of the chromatoplates. 

Edge, T., Smith, C., Hill, S., Picard, P., Letarte, S., Wilson, I. D., and Vince, P. (2008). Comparison of laser diode thermal desorption (LDTD) source vs LC-MS for the analysis of a theraputic drug in biological extracts. In Proceedings of the 56th ASMS Conference on Mass Spectrometry and Allied Topics. ASMS, Denver, CO. 

Field desorption analysis therefore offers an opportunity to survey biological extracts for abnormal distributions of these compounds without necessitating extensive chemical workup. 

As an instrumental approach to conventional electrophoresis, capillary electrophoresis offers the capability of on-line detection, micropreparative operation and automation (6,8,45-47). In addition, the in tandem connection of capillary electrophoresis to other spectroscopy techniques, such as mass spectrometry, provides high information content on many components of the simple or complex peptide under study. For example, it has been possible to separate and characterize various dynorphins by capillary electrophoresis-mass spectrometry (33). Therefore, the combination of CE-mass spectrometry (CE-MS) provides a valuable analytical tool useful for the fast identification and structural characterization of peptides. Recently, it has been demonstrated that the use of atmospheric pressure ionization using Ion Spray Liquid Chromatography/ Mass Spectrometry is well suited for CE/MS (48). This approach to CE/MS provides a very effective and straightforward method which allow the feasibility of obtaining CE/MS data for peptides from actual biological extracts, i.e., analysis of neuropeptides from equine cerebral spinal fluid (33). 

The most unique and valuable feature of Probability Based Matching, when applied to biological extracts, is its ability to automatically detect the existence of contaminations in a GC peak and to eliminate their interferences. This unusual feat can be accomplished because PBM is a "self-adapting" SIM technique i.e. the computer decides which ions in the contracted spectrum contain valid data and concurrently rejects ions that are contaminated due to the presence of impurities. 

O Neill and Sakamoto reported an enzymatic fluorimetric method for the determination of acetylcholine in biological extracts [41]. Nanomolar amounts of acetylcholine were determined in perchloric acid extracts of biological materials (brain tissues) by use of a system containing acetylcholineesterase, acetyl CoA synthetase, maleate dehydrogenase, and citrate synthase. The production of NADH2 was stoichiometrically related to the amount of acetylcholine in the system, and was followed fluorimetrically. Interfering fluorescent substances in the brain extracts were removed with acid-washed Florisil. 

In the usual instance it is necessary to use more than one analytical tool for identification (and separation) of the phospholipids in a biological extract. Other chromatographic techniques of value will be discussed later. However, now it is worthwhile to describe a methodology by which a nearly quantitative... 

M. Kotrebai S. M. Bird, J. F. Tyson, E. Block, P. C. Uden, Characterization of selenium species in biological extracts by enhanced ion-pair liquid chromatography with inductively coupled plasma mass spectrometry and by referenced electrospray ionization mass spectrometry, Spectrochim. Acta, 54B (1999), 1573D1591. 

K. A. Francesconi, S. A. Pergantis, Application of selected reaction monitoring tandem mass spectrometry to the quantitative determination of an arsenic-containing nucleoside in a crude biological extract, Analyst, 129 (2004), 398-399. 

Scaling die rows to a constant total is useful if the absolute concentrations of samples cannot easily be controlled. An example might be biological extracts the precise amount of material might vary unpredictably, but the relative proportions of each chemical can be measured. This method of scaling introduces a constraint which is often called closure. The numbers in the multivariate data matrix are proportions and... 

Techniques used to identify new carotenoids are also employed to identify carotenoid metabolites in various photosynthetic organisms, as well as animals and humans. A new metabolite might be identified in a food or biological extract by HPLC-PDA, with the observation of a new peak with a UVA is spectrum similar to a carotenoid, or which produces an MS fragment similar to other known carotenoids. Alternatively, the metabolism may be induced in vitro by creating ideal biological conditions for generating metabolites (with intestinal mucosa, for example dos Anjos Ferreira et ah, 2004). 

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