The Colorimetric Determination of Phosphoric Acid in Hydrochloric Acid and Citric Acid Extracts of Soils

1930 ◽  
Vol 20 (4) ◽  
pp. 532-540 ◽  
Author(s):  
R. G. Warren ◽  
A. J. Pugh
Keyword(s):  
Citric Acid ◽  
Phosphoric Acid ◽  
Gravimetric Method ◽  
Potassium Ferrocyanide ◽  
Clay Soils ◽  
Acid Extraction ◽  
Colorimetric Determination ◽  
Colour Development ◽  
Good Agreement

1. The colorimetric determination of phosphoric acid in hydrochloric and citric acid extracts of soils by a method involving the evaporation of the extract, ignition and acid extraction of the residuewith either the Denigès and Fiske-Subbarow methods of colour development was satisfactory only with light soils. Clay soils gave low results owing to the presence of larger amounts of iron.2. A method is given in which the organic matter and iron are removed by treatment with sodium permanganate and potassium ferrocyanide. The results are in good agreement with the gravimetric method.

Determination of Sevin Insecticide Residues in Fruits and Vegetables

1964 ◽  
Vol 47 (2) ◽  
pp. 283-286
Author(s):  
D P Johnson
Keyword(s):  
Fruits And Vegetables ◽  
Collaborative Study ◽  
Colorimetric Determination ◽  
Average Recovery ◽  
Insecticide Residues ◽  
Chromogenic Agent ◽  
Hydrolysis Of ◽  
Concentration Levels ◽  
Good Agreement

Abstract Collaborative study of a method for Sevin insecticide residues was repeated with apples and lettuce as test crops. The method is based on alkaline hydrolysis of Sevin and colorimetric determination of the resulting 1-naphthol with p-nitrobenzenediazonium fluoborate as chromogenic agent. Data from 5 collaborators were in good agreement with an average recovery of 87.8% at 2 concentration levels. It is recommended that the method be adopted as official, first action.

Simplified Method for Determination of Total Dietary Fiber in Foods

1988 ◽  
Vol 71 (5) ◽  
pp. 1063-1064
Author(s):  
Betty W Li ◽  
Karen W Andrews
Keyword(s):  
Dietary Fiber ◽  
Incubation Period ◽  
Gravimetric Method ◽  
Food Samples ◽  
Total Dietary Fiber ◽  
Collaborative Studies ◽  
Simplified Method ◽  
Good Agreement

Abstract A simplified method, based on the same principles as the AOAC enzymatic-gravimetric method for determining total dietary fiber (TDF) (43.A14-43.A20), has been tested on 12 food samples which had been used in other collaborative studies. TDF values obtained in our laboratory for these 2 methods were in good agreement (y = 0.96x + 0.39; r = 0.999). The simplified method uses a single incubation period and only 1 enzyme (amyloglucosidase), and thus yields smaller blank and ash corrections but a higher protein correction.

scholarly journals DETERMINATION OF TYPE OF SOLVATE OF PHOSPHORIC ACID DURING ITS EXTRACTION BY TRIBUTYL PHOSPHATE

2019 ◽  
Vol 62 (5) ◽  
pp. 104-109
Author(s):  
Nikolai F. Kizim ◽  
Anastasiya E. Tarasenkova
Keyword(s):  
Phosphoric Acid ◽  
Aqueous Solutions ◽  
Aqueous Phase ◽  
Equilibrium Constants ◽  
Material Balance ◽  
Mass Action ◽  
Acid Extraction ◽  
Processes And Reactions ◽  
Ionic Equilibria

The extraction of phosphoric acid with a solution of tri-n-butyl phosphate (TBP) in toluene from its individual aqueous solutions in a concentration range of 0-11 M is investigated. The experiments are performed at room temperature (20 ± 1 °С). The isotherms of extraction of phosphoric acid under conditions of equality of the volumes of the saturating aqueous phase and the receiving organic phase are constructed. The extraction isotherm is nonlinear, but to an acid concentration in the aqueous phase of ~ 8 M, it is close to linear, and at higher concentrations, the amount of extracted acid increases harshly. To establish the mechanism of acid extraction in the system phosphoric acid – 0.1 M solution of TBP in toluene the method of combining a laboratory and computational experiment is proposed. The optimal parameters describing the extraction of phosphoric acid from natural aqueous solutions are determined. Calculations performed in two approximations were made. In the first approximation the condition of ideality of systems is accepted. In the second approximation the deviations of the properties of phosphoric acid solutions in aqueous solution are taken into account. For the two approximations the preferential extraction of phosphoric acid molecules in the form of H3PO4 ∙ nTBP type solvates (where n = 1, 3) is shown. In the range of concentrations of phosphoric acid in the aqueous phase from 6 to 11 M, the values of equilibrium constants are estimated, which describe the processes and reactions occurring in the system: stepwise dissociation of acid, distribution of TBP, formation of solvates of phosphoric acid, distribution of the resulting solvates of acid, displacement of ionic equilibria in aqueous phase. Mathematically these processes are taken into account using the law of mass action and the equations of material balance. It is believed that the system has established an equilibrium corresponding to a given temperature and pressure. The calculated values of solvate concentrations are in satisfactory agreement with experimental data.

Determination of Edrophonium Chloride Injection USP in the Presence of Preservatives

1979 ◽  
Vol 62 (5) ◽  
pp. 1110-1112
Author(s):  
Thomas W Hamill
Keyword(s):  
Phosphoric Acid ◽  
Ion Pair ◽  
Partition Chromatography ◽  
Ultraviolet Absorbance ◽  
Good Agreement

Abstract The determination of Edrophonium Chloride Injection involves a modification of a procedure for phenylephrine and offers an alternative to the compendial assay. Edrophonium chloride forms an ion-pair with di-(2-ethylhexyl) phosphoric acid which can be extracted with an immiscible solvent such as ether. When this procedure is coupled with partition chromatography, the drug can be isolated from preservatives and quantitatively determined by its ultraviolet absorbance. Recovery data on synthetic mixtures ranged from 99.8 to 101.9% and were in good agreement with the compendial method.

scholarly journals VI.— A chemical Study of the phosphoric Acid and potash contents of the wheat Soils of broadbalk rothamsted

1901 ◽  
Vol 194 (194-206) ◽  
pp. 235-290 ◽  
Keyword(s):  
Citric Acid ◽  
Phosphoric Acid ◽  
Chemical Study ◽  
Chemical Society ◽  
Flowering Plants ◽  
Plant Food ◽  
Cent Solution ◽  
Preliminary Examination ◽  
The Subject

In 1894 the author contributed to the ‘Journal of the Chemical Society’ (vol. 65, ‘ Trans.,’ March, 1894) a paper 011 “ The Determination of Available Mineral Plant Food in Soils,” in which the use of a 1 per cent, solution of citric acid was proposed as a means of approximately differentiating by means of chemical analysis between the total and the probably available phosphoric acid and potash in soils. The reasons leading up to the tentative adoption of this solution, together with a summary of previous literature on the subject, are given in the original paper, and it need, therefore, now only be said that the method was the result of an attem pt to imitate, in the solvent used, the acidity of root-sap, based on a preliminary examination of the root acidity of 100 specimens of flowering plants representing some 20 natural orders. In order to test the proposed method it was applied to 22 samples of soil drawn from the various plots in Hoos Field, Rothamsted, on which barley under very various manurial conditions had been continuously grown for over forty years. The samples were placed at the author’s disposal by the kindness of Sir John Lawes and Sir Henry Gilbert. The results of this investigation, which are fully set forth in the paper referred to, were of sufficient interest to lead to the undertaking of a similar but much more extended examination of the soils of the Rothamsted wheat plots in Broadbalk Field.

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