The Quantitative Determination of Zinc in Transparent Rubber Articles

1940 ◽  
Vol 13 (1) ◽  
pp. 181-184 ◽  
Author(s):  
Edmondo Casazza
Keyword(s):  
Quantitative Determination ◽  
Zinc Content ◽  
Potassium Ferrocyanide ◽  
The Novel ◽  
Inorganic Substances ◽  
Porcelain Crucible ◽  
Zinc Salts ◽  
Concentrated Sulfuric Acid ◽  
Standard Solution

Abstract The method to be described is particularly suitable for the quantitative determination of zinc, present in the form of zinc oxide or of zinc salts, in transparent rubber articles. Rubber articles of this type contain very small quantities of zinc compared with the quantities present in non-transparent rubber articles, in fact the lower limit is only 0.05 per cent, i.e., only about one-hundredth as much as the normal content. The analytic determination of the zinc content when present in such extremely low percentages as this is extremely difficult by ordinary, methods, and even with higher but nevertheless small percentages of zinc, the use of relatively large quantities of material is necessary and the analytical results are often far from precise. The ordinary method of incineration in a porcelain crucible does not lend itself to the isolation of small quantities of zinc because the latter is easily fixed by the silica of the crucible. On the other hand incineration in a platinum crucible is not suitable because of the tendency of this metal to form a carbide in contact with the carbonaceous substances in the rubber. The novel feature of the method of analysis to be described is the procedure for obtaining a solution of the inorganic substances in the rubber. This involves destruction of the rubber by concentrated sulfuric acid and subsequent oxidation of the organic residue by concentrated nitric acid. This gives a solution of the zinc in the form of sulfate. It is then isolated as zinc sulfide and is redissolved and determined volumetrically by the already known method of precipitation with a standard solution of potassium ferrocyanide. The most suitable concentration, acidity and temperature to give precise results by this procedure for low percentages of zinc in rubber were established.

scholarly journals Development and Validation of Method for the Quantitative Determination of Zinc in its Chelate Complexes Using Energy Dispersive X-ray Fluorescence Spectroscopy

2021 ◽  
Vol 10 (4) ◽  
pp. 154-161
Author(s):  
А. V. Marukhlenko ◽  
Т. V. Maksimova ◽  
Т. V. Pleteneva ◽  
М. A. Morozova
Keyword(s):  
Fluorescence Spectroscopy ◽  
Aqueous Solutions ◽  
Quantitative Determination ◽  
Zinc Sulfate ◽  
Zinc Content ◽  
Chelate Complex ◽  
Molar Ratio ◽  
X Ray ◽  
Validation Parameters

Introduction. The production, standardization and quality control process of various dietary supplements containing chelated zinc requires validated quantitative assessment methods. In this work, we propose an X-ray fluorescence spectroscopy (XRF) technique for determining the zinc content in the composition of coordination compounds using the example of a synthesized chelate complex with methionine.Aim. To synthesize Zn(Met)2 chelate complex, to develop and validate a method for its quantitative analysis using the XRF method.Materials and methods. The synthesized zinc chelate complex was investigated by IR spectroscopy. The XRF method was used to develop a method for quantifying the zinc content in the synthesized complex. We used dry mixtures of zinc sulfate monohydrate and L-methionine (Met) in a molar ratio of Zn to Met – 1 : 1, 1 : 2, 1 : 4, 1 : 8 and 1 : 16 and also aqueous solutions of zinc sulfate and L-methionine in a molar ratio of Zn to Met 1 : 2 with Zn concentrations from 0.5 to 100 mmol/l as calibration standards. Complexometric titration was used as an arbitration method for the quantitative determination of zinc content in the samples under study.Results and discussion. The IR spectrum of chelate complex confirmed the presence of a donor-acceptor bond between Zn2+ and the nitrogen atom of amino group in methionine. The titration results showed chelate compounds have a composition corresponding to the stoichiometric formula Zn(Met)2. XRF analysis of dry standard mixed samples demonstrated the presence of matrix effect, that makes impossible an accurate assessment of zinc content in the chelate compound. According to the XRF spectra of aqueous solutions containing zinc sulfate and methionine in a ratio of 1 : 2 at a zinc concentration of 0.5; 1; 2; 3; 4; 5; 10; 25; 50 and 100 mmol/L, a calibration graph was constructed – the dependence of the fluorescence signal intensity for the Kα line of zinc on the concentration of zinc in the solution (r = 0.9996). The method was evaluated by the following validation parameters: specificity, linearity, correctness, precision, and analytical range. The specificity of the validated method was proven in the presence of copper, iron, and silver.Conclusion. The developed method make it possible to determine with sufficient precision and correctness the content of Zn2+ in its aqueous solutions of inorganic and organic nature by the XRF method in the concentration range from 3 to 100 mmol/l without the influence of the matrix.

Bromination of Acridine

2018 ◽  
Vol 71 (4) ◽  
pp. 285
Author(s):  
Graham S. Chandler ◽  
Wolfgang H. F. Sasse
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Quantitative Determination ◽  
Glacial Acetic Acid ◽  
Tiny Amount ◽  
Concentrated Sulfuric Acid

The quantitative determination of the products of bromination of acridine in concentrated sulfuric acid and glacial acetic acid is described. In both cases, the only monobromo products were the 2- and 4-substituted compounds. With sulfuric acid, the 4-isomer predominates whereas in acetic acid, the 2-isomer is predominant. This work expands substantially on the tiny amount of previous work on halogenation of dibenzo-annelated pyridines.

The Controlled Atmosphere Direct Current Arc for the Quantitative Determination of Trace Metals in Organics

1965 ◽  
Vol 19 (3) ◽  
pp. 89-91 ◽  
Author(s):  
D. L. Nash
Keyword(s):  
Trace Metals ◽  
Quantitative Determination ◽  
Internal Standard ◽  
Ash Content ◽  
Small Sample ◽  
Controlled Atmosphere ◽  
Fixed Amount ◽  
Standard Solution ◽  
Dc Arc

A method has been developed to permit the quantitative determination of trace metals in polypropylene and other organic materials in which the total ash content ranges from 0.10 per cent to less than 0.001 per cent by weight. A small sample of the material is ashed directly in the electrode. A fixed amount of germanium internal standard solution is added to the electrode and dried Standards are prepared by adding weighed amounts of a plastic dispersion containing known amounts of the elements to be determined to specially prepared electrodes. Using a controlled atmosphere chamber the prepared electrodes are excited with a dc arc in an atmosphere of argon and oxygen and the spectra recorded photographically.

The Quantitative Determination of Rubber Chemicals

1957 ◽  
Vol 30 (4) ◽  
pp. 1017-1026 ◽  
Author(s):  
Otto Lorenz ◽  
Elisabeth Echte
Keyword(s):  
Quantitative Determination ◽  
Chloride Solution ◽  
Silver Salt ◽  
Stannous Chloride ◽  
Zinc Salt ◽  
Iodine Solution ◽  
Experimental Conditions ◽  
Zinc Salts ◽  
Free Sulfur

Abstract 1. Both the precipitation of mercaptobenzothiazole as a silver salt and its oxidation with an iodine solution to a disulfide may be utilized for quantitative determination. 2. Zinc benzothiazolyl mercaptide can be determined iodometrically, either directly or indirectly, after being cleaved by acids. 3. Benzothiazolyl disulfide is determined as mercaptobenzothiazole after reduction with acidic stannous chloride solution. 4. A procedure for the determination of a mixture of mercaptobenzothiazole, zinc benzothiazolyl mercaptide, and dibenzothiazolyl disulfide is described. 5. Experimental conditions are indicated, under which the quantitative determination of free sulfur is possible in the presence of mercaptobenzothiazole, its zinc salt, the disulfide, and the zinc salts of fat acids. In all cases the uncombined sulfur is determined after its conversin to thiocyanate by an argentometric conductivity titration of the thiocyanate.

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