Chelate digestion

The common chemical methods for extraction of PHB are solvent extraction, chemical digestion using sodium hypochlorite, sodium hypochlorite and chloroform, surfactants, surfactant hypochlorite digestion, surfactant chelate digestion, chelate hydrogen peroxide treatment, selective dissolution of nonpolymer cell mass by proton etc. 

Agricultural Use. Citric acid and its ammonium salts are used to form soluble chelates of iron, copper, magnesium, manganese, and zinc micronutrients in Hquid fertilizers (97—103). Citric acid and citrate salts are used in animal feeds to form soluble, easily digestible chelates of essential metal nutrients, enhance feed flavor to increase food uptake, control gastric pH and improve feed efficiency. 

Pectins were extracted from isolated cell walls of 5-week-old wheat plants using different methods. Enzymic digestions of the cell walls involved pectinases such as a commercial pectolayse or recombinant endopolygalacturonase [Maness Mort, 1989]. Chemical extractions involved the chelating agent imidazole [Mort et al., 1991] or solvolysis with anhydrous HF at 0 °C in a closed teflon line [Mort et al., 1989] followed by imidazole extraction. 

Li, M., and Meares, C.F. (1993) Synthesis, metal chelate stability studies, and enzyme digestion of a peptide-liked DOTA derivatives and its corresponding radiolabeled immunoconjugates. Bioconjugate Chem. 4, 275-283. 

Ammonium pyrrolidine dithiocarbamate (APDC) chelate coprecipitation coupled with flameless atomic absorption provides a simple and precise method for the determination of nanomol kg 1 levels of copper, nickel, and cadmium in seawater. With practice, the method is not overly time-consuming. It is reasonable to expect to complete sample concentration in less than 20 min, digestion in about 4 h, and sample preparation in another hour. Atomic absorption time should average about 5 min per element. Excellent results have been obtained on the distribution of nickel and cadmium in the ocean by this technique. 

Mn, Fe, Co, Ni, Cu, Zn Biological materials Solvent extraction, digest chelates 222)... 

Moment of inertia, exponents of dimensions in absolute, gravitational, and engineering systems, 8 584t Momentum balance equation, 21 347-348 Momentum equation, 11 738, 739-743 Momentum flowmeters, 11 671 Monactin, chelating agent, 5 710 Monazite, 5 671 14 636 24 756-757 digestion of, 14 638 processing, 5 673 Monel, 14 14 Monel alloy, 9 595 Monel alloy 400, 17 100 Monel cathodes, 11 837 Monensin, 20 132, 133, 135, 136, 137, 139 Monensin A, 20 120... 

A schematic diagram of the automatic system is shown in Fig. 4.12. It consists of five component modules a sample introduction unit, a digestion unit, a neutrafization vessel, a chelation and extraction vessel and an extract collection unit. The sy stem is controlled by a series of interacting cam and electronic process timers. 

The control system is largely situated in a series of 19" rack-mounted units. As far as possible, each of these units is self-contained with one controlhng the sample introduction unit, one the neutralization unit, one the chelation—extraction and extract collection units and another being used as the source of the various power supphes. The neutralization controller and phase boundary sensor are situated in small separate units and the digestion unit controller is incorporated into the digester module. 

Molybdenum may be identified at trace concentrations by flame atomic absorption spectrometry using nitrous oxide-acetylene flame. The metal is digested with nitric acid, diluted and analyzed. Aqueous solution of its compounds alternatively may be chelated with 8—hydroxyquinobne, extracted with methyl isobutyl ketone, and analyzed as above. The metal in solution may also be analyzed by ICP/AES at wavelengths 202.03 or 203.84 nm. Other instrumental techniques to measure molybdenum at trace concentrations include x-ray fluorescence, x-ray diffraction, neutron activation, and ICP-mass spectrometry, this last being most sensitive. 

Recent review articles (, 104-109) have described general factors that affect mineral utilization from foods. General factors such as the digestibility of the food that supplies the mineral, chemical form of the element, dietary levels of other nutrients, presence of mineral chelators, particle size of the food or supplemented minerals and food processing conditions all play a role in the ultimate mineral bioavailability (104). Many unit food processing operations can be shown to directly or indirectly alter the level or chemical form of minerals or the association of minerals with other food components. 

Little agreement has been reached as to which dietary components or which food processes physiologially affect mineral availability. Many plant foods contain phytic acid, oxalic acid or other dietary fiber components that can be shown to chelate minerals. The effect of these dietary substances upon the final bioavailability of the mineral in question will depend upon the digestibility of the chelate (106). 

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