Determination phosphate content

The relation between free phosphoric acid content and total phosphate content in a processing bath, whether based on iron, manganese or zinc, is very important this relation is generally referred to as the acid ratio. An excess of free acid will retard the dissociation of the primary and secondary phosphates and hinder the deposition of the tertiary phosphate coating sometimes excessive loss of metal takes place and the coating is loose and powdery. When the free acid content is too low, dissociation of phosphates (equations 15.2, 15.3 and 15.4) takes place in the solution as well as at the metal/solution interface and leads to precipitation of insoluble phosphates as sludge. The free acid content is usually determined by titrating with sodium... 

Determine the phosphate content of an unknown solution, containing say ca 0.005 mg P205 per mL use the calibration graph. 

Provided only polyphosphates are present it is possible to determine titrimetrically (1) the end-group content of mixtures (2) the content of groups within the chain, after hydrolysis and by estimating the total phosphate content (3) the monophosphate content after precipitation with silver nitrate (347). These methods are likewise of no use in presence of meta- and cross-linked phosphates. 

Two 0.5-g samples were taken from each beaker for moisture and pH determination. Moisture content was measured by gravimetry, and pH was measured after adding 5 mL of deionized water to the sample, using a pH meter. The enzyme was extracted from the remaining fermented cake by adding 45 mL of sodium phosphate buffer (100 mmol/L, pH 7.0) following incubation at 35°C and 200 rpm for 30 min. After filtration the liquid phase was used for determination of lipase activity. 

X-ray absorption study of tribofilms generatedfrom a combination of ZDDP and borate-sulfonate RMs was used to determine the chemistry of tribochemical films at the surface and the bulk The calcium phosphate content in the tribofilm generated from either ZDDP + borate-sulfonate RMs or from ZDDP + calcium sulfonate soft-core RMs is similar (Varlot et al., 2001). Calcium sulfonate S(+5) undergoes disproportion reaction to form sulfate S(+6) and sulfite S(+4), and the presence of ZDDP affects the disproportion process. Close to the steel surface, the... 

The TNBS-method (TriNitroBenzeneSulfonic acid) was used to determine the content of "free amino groups" in the sample solutions. The samples from the reaction mixture were diluted with a phosphate buffer (0.01 M pH-8), so that a glycine concentration was obtained in the order of 1.10 g.1 1. 

Acetyl Groups Determine the content of acetyl groups in starch acetate, acetylated distarch adipate, and acetylated distarch phosphate as directed under Acetyl Groups, Appendix X. 

Plot the data yielded from step 2-37 as shown in Figure 2-16. What is the extinction coefficient of the complex produced in this procedure Unknown samples are assayed in an identical manner and their phosphate content determined from the standard curve prepared above. 

Since the determination of LC20 phosphate content varies among laboratories by two- to threefold, one cannot establish a stoichiometry of the phosphorylation in either the initial or steady state of contraction. Measurements in this laboratory with arterial and uterine muscles, which produced maximal stress and phosphorylation, suggest that both myosin heads are phosphorylated in the initial and one head in the sustained phase of contraction. The other extreme, contraction without phosphorylation, does not occur in our experience. 

In situ analysis of mineral content and crystallinity in bone. Bone, a functionally gradient material, is composed of protein and mineral components which give rise to spectral absorptions in the mid and far-infrared spectral range. Recently, Miller et al. (2001) have initiated an investigation of cross sections of human iliac crest bones, collecting the IR absorption spectra around a human osteon. The focus of this investigation was to measure the acid phosphate content and determine mineral crystallite perfection from the . spectra. The crystallite perfection was determined from a concurrent study of the correlation of IR absorption spectra with X-ray powder diffraction results from a series of synthetic hydroxyapatite crystals and natural bone powders of various species and ages. 

Reconstitution experiments with apoferritins from animal and bacterial sources, whose native iron-loaded ferritins had crystalline and amorphous cores respectively, have been informative in showing that the core morphology is not determined by the protein shell. For example, Baaghil et al and Mann et al were able to form crystalline cores in bacterioferritins, and Rohrer et al formed cores of iron-phosphate in horse spleen ferritin with fewer short range Fe-Fe distances than in the native cores. Thus it appears that the composition of the medium within which the ferritin cores are laid down, particularly the phosphate content, influences strongly the nature of the core. This is consistent with the role of phosphate as an iron oxide chain terminator. 

The most sensitive test for the level which will first promote dissolution of bone can be found in adult animals on a diet which is optimal in calcium and phosphate content, by determining the minimal dose which will increase the output of calcium in the urine over and above that extra amount absorbed. 

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