scholarly journals Colorimetric Determination of Selenium in Mineral Premixes

1997 ◽  
Vol 80 (4) ◽  
pp. 709-716
Author(s):  
Jeffrey A Hurlbut ◽  
Roger G Burkepile ◽  
Carolyn A Geisler ◽  
Philip James Kliak ◽  
Nathan G Rummel
Keyword(s):  
Calcium Carbonate ◽  
Sodium Selenite ◽  
Ethylenediaminetetraacetic Acid ◽  
Base Material ◽  
Magnesium Carbonate ◽  
Sodium Selenate ◽  
Colorimetric Determination ◽  
Sample Type ◽  
Coefficients Of Variation

Abstract A method is described for determination of sodium selenite or sodium selenate in mineral-based premixes. It is based on the formation of intense-yellow piazselenol by Se(IV) and 3,3’-diaminobenzid- ine. Mineral premixes typically contain calcium carbonate as a base material and magnesium carbonate, silicon dioxide, and iron(lll) oxide as minor components or additives. In this method, the premix is digested briefly in nitric acid, diluted with water, and filtered to remove any iron(lll) oxide. Ethylenediaminetetraacetic acid and HCI are added to the filtrate, which is heated to near boiling for 1 h to convert any selenate to selenite. After heating, the solution is buffered between pH 2 and 3 with NaOH and formic acid and treated with NH2OH and EDTA; any Se present forms a complex with 3,3’- diaminobenzidine at 60°C. The solution is made basic with NH4OH, and the piazselenol is extracted into toluene. The absorbance of the complex in dried toluene is measured at 420 nm. The method was validated independently by 2 laboratories. Samples analyzed included calcium carbonate fortified with 100, 200, and 300 μg Se in the form of sodium selenite or sodium selenate, a calcium carbonate premix containing sodium selenite, a calcium carbonate premix containing sodium selenate, and a commercial premix; 5 replicates of each sample type were analyzed by each laboratory. Average recoveries ranged from 89 to 109% with coefficients of variation from 1.2 to 13.6%.

Dry Ashing Technique for the Determination of Arsenic in Marine Fish

1973 ◽  
Vol 56 (2) ◽  
pp. 383-386 ◽  
Author(s):  
Patrick J Leblanc ◽  
Adrian L Jackson
Keyword(s):  
Marine Fish ◽  
Inorganic Arsenic ◽  
Fish Tissue ◽  
Magnesium Nitrate ◽  
Colorimetric Determination ◽  
Muffle Furnace ◽  
Coefficients Of Variation ◽  
Dry Ashing ◽  
Wet Weight

Abstract A dry ashing procedure, followed by the silver diethyldithiocarbamate colorimetric determination of arsenic in marine fish, is presented. The sample is first homogenized and a portion is pre-ashed with magnesium nitrate, using infrared heat, followed by ashing in a 500°C muffle furnace. The residue is dissolved in HCl and the arsenic is reduced by means of zinc and HCl to arsine, which is complexed with AgDDC and determined colorimetrically at 535 nm. At temperatures of 460°C and above, efficient ashing was obtained. The effect of various volumes of ashing aid (50% magnesium nitrate) was also studied. Maximum recovery and precision were obtained when a minimum of 8 ml 50% magnesium nitrate was used. Standard recoveries of inorganic arsenic added to NBS orchard leaves and a sample of dry marine fish tissue gave values of 91–98%. Analyses of a number of standard NBS orchard leaves and marine fish As-1 and As-2 gave coefficients of variation of 7.0, 6.0, and 8.1%, respectively. Results from dry ashing and wet digestion of a number of species of marine fish were not comparable. Levels of arsenic found in different species of marine fish ranged from <0.4 to 27.0 μg As/g wet weight. Crabs were found to contain elevated amounts of arsenic.

Semiautomated Colorimetric Determination of Methenamine and Methenamine Mandelate in Tablets

1973 ◽  
Vol 56 (3) ◽  
pp. 647-652 ◽  
Author(s):  
Matthew L Dow
Keyword(s):  
Chromotropic Acid ◽  
Assay Method ◽  
Colorimetric Determination ◽  
Coefficients Of Variation ◽  
Colorimetric Procedure

Abstract A semiautomated chromotropic acid colorimetric procedure was collaboratively studied by 6 laboratories, both as a composite assay and as an individual tablet assay method. Results agreed well with the USP and NF methods. The coefficients of variation ranged from 0.54 to 2.48%. The method has been adopted as official first action for the analysis of coated and uncoated tablets of methenamine mandelate, methenamine, and methenamine with sodium biphosphate.

Collaborative Study of the Nonaqueous Copper Colorimetric and Silver Titrimetric Methods for the Determination of Malathion in Technical Grade Malathion and in Malathion Formulation

1973 ◽  
Vol 56 (3) ◽  
pp. 579-585
Author(s):  
Richard S Wayne
Keyword(s):  
Excellent Agreement ◽  
Collaborative Study ◽  
Colorimetric Method ◽  
Sample Type ◽  
Technical Grade ◽  
Coefficients Of Variation ◽  
The Mean

Abstract The nonaqueous copper colorimetric and the silver titrimetric methods for the determination of malathion were studied collaboratively. The study involved wettable powders, emulsifiable concentrates, dusts, and the technical grade product. The mean of all of the results indicates that both procedures will give comparable values for each sample type used in the study. Agreement between replicates in individual laboratories was excellent. Agreement between laboratories was satisfactory; coefficients of variation ranged from 1.3 to 4.8% for the samples studied. The 2 methods offer improved reliability and ease of operation when compared to the official first action colorimetric method, 6.265–6.269. The methods have been adopted as official first action.

scholarly journals An improved method for determining the mass fraction of calcium carbonate in the carbonate bedrock

10.5219/1591 ◽  
2021 ◽  
Vol 15 ◽  
pp. 877-890
Author(s):  
Tatiana Kos ◽  
Inha Kuznietsova ◽  
Tamila Sheiko ◽  
Liubomyr Khomichak ◽  
Yuliia Kambulova ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Material Balance ◽  
Component Composition ◽  
Magnesium Carbonate ◽  
Maximum Energy ◽  
Environmental Friendliness ◽  
Complete Chemical Analysis ◽  
Carbonate Material ◽  
Definition Of

In the article it is offered to enter in the technological audit of the lime department of sugar factory the adjusted technique of the definition of the maintenance of calcium carbonate in carbonate breed. For this purpose, a complete chemical analysis of limestone was performed, which includes determination of moisture content, impurities insoluble in hydrochloric acid, the amount of one and a half oxides of aluminum and iron, calcium carbonate (advanced method), and magnesium carbonate, calcium sulfate, alkali metal oxides, potassium, and sodium. The obtained experimental data are summarized in one table and the material balance of all components of carbonate bedrock is summarized. The proposed method made it possible to obtain objective data on the component composition of the carbonate material. This, in turn, avoids many technological problems, namely to reduce the formation of melts in the lime kiln, improve the filtration of juices, increase the ability of lime to chemically interact with water, reduce the volume of water on the juicer etc. Thus, the use of the recommended method for determining calcium carbonate (CaCO3), as part of the technological audit, will allow early adjustment of the process, which will give maximum energy and resource savings, as well as increase the level of environmental friendliness of the enterprise.

Colorimetric Determination of Aniline Derivatives in Natural Waters

1971 ◽  
Vol 54 (6) ◽  
pp. 1383-1387 ◽  
Author(s):  
M A El-Dib
Keyword(s):  
Surface Waters ◽  
Natural Waters ◽  
Colorimetric Method ◽  
Colorimetric Determination ◽  
Color Intensity ◽  
Aniline Derivative ◽  
Aniline Derivatives ◽  
Coefficients Of Variation ◽  
Effects Of Ph

Abstract A rapid, direct, and sensitive colorimetric method has been proposed for the determination of aniline derivatives in surface waters. The method is based on diazotization of the primary aromatic amine and coupling with resorcinol or 1-naphthol. Hydroxy-azo dyes obtained have considerably high absorptivities, rendering the method sensitive enough to determine anilines at 0.1 ppm. The effects of pH, saline constituents of waters, coupling phenols, and substituents on color intensity are discussed. Coefficients of variation ranged between 6 and 0.5, according to the nature of aniline derivative and the amount determined. Precision of the method is greatly increased when the amount of the existent aniline ranges between 40 and 100 μg.

Collaborative Study of the Colorimetric Determination of Zirconium in Antiperspirant Aerosols

1977 ◽  
Vol 60 (3) ◽  
pp. 663-668
Author(s):  
Paul Beavin
Keyword(s):  
Statistical Evaluation ◽  
Collaborative Study ◽  
Colorimetric Determination ◽  
Fusion Procedure ◽  
Coefficients Of Variation ◽  
Zirconium Compounds ◽  
Insoluble Form ◽  
Standard Deviations ◽  
Insoluble Compounds

Abstract A previously published method for determining zirconium in antiperspirant aerosols was collaboratively studied by 7 laboratories. The method consists of 2 procedures: a rapid dilution procedure for soluble zirconium compounds or a lengthier fusion procedure for total zirconium (soluble and insoluble compounds), followed by colorimetric determination. The collaborators were asked to perform the following: Spiking materials representing 4 levels of soluble zirconium were added to weighed portions of a zirconium-free cream base concentrate and the portions were assayed by the dilution procedure. Spiking materials representing 4 levels of zirconium in either the soluble or the insoluble form (or as a mixture) were also added to portions of the same concentrate and these portions were assayed by the fusion procedure. They were also asked to concentrate and assay, by both procedures, 2 cans each of 2 commercial aerosol antiperspirants containing zirconyl hydroxychloride. The average per cent recoveries and standard deviations for spiked samples were 99.8–100.2 and 1.69–2.71, respectively, for soluble compounds determined by the dilution procedure, and 93.8–97.4 and 3.09–4.78, respectively, for soluble and/or insoluble compounds determined by the fusion procedure. The average per cent zirconium found by the dilution procedure in the 2 commercial aerosol products was 0.751 and 0.792, respectively, with coefficients of variation of 2.94 and 2.53%, respectively. Insufficient collaborative results were received for the fusion procedure for statistical evaluation. The dilution procedure has been adopted as official first action.

Collaborative Study of a Colorimetric Determination of Nitroglycerin in Sublingual Tablets

1972 ◽  
Vol 55 (1) ◽  
pp. 187-189
Author(s):  
Yvonne H Pfabe
Keyword(s):  
Collaborative Study ◽  
Colorimetric Determination ◽  
Coefficients Of Variation ◽  
Ethylenediamine Dihydrochloride ◽  
The Individual ◽  
Low Dosage

Abstract The colorimetric determination of nitroglycerin in tablets (JAOAC 53, 579–581 (1970)) was collaboratively studied by 13 laboratories. The nitroglycerin is hydrolyzed to nitrite, which diazotizes p-chloroaniline; this diazotization product is coupled with N-(l-naphthyl)- ethylenediamine dihydrochloride and measured at 560 nm. Samples were analyzed at a composite level (1.2 mg) and at an individual tablet level (0.15–0.6 mg). Coefficients of variation ranged from 4 to 14%, with the highest variation in the individual assay of low dosage tablets. Samples analyzed by the Associate Referee 6 months after the first analysis showed lower assay results, indicating deterioration. It is recommended that this study be continued.

Features of determination of native carbon in carbon-containing rocks on the analyzer of carbon and water

2021 ◽  
Vol 87 (7) ◽  
pp. 23-29
Author(s):  
N. A. Feoktistov ◽  
V. Р. Chernov ◽  
К. G. Pivovarova ◽  
Т. В. Ponamareva ◽  
I. V. Mikhalkina
Keyword(s):  
Calcium Carbonate ◽  
Bound Water ◽  
Magnesium Carbonate ◽  
Carbonate Content ◽  
South Urals ◽  
Temperature Range ◽  
Burn Out ◽  
Carbon Determination ◽  
Ir Spectroscopic

The largest deposits of graphite in the Russian Federation are located in the Middle and South Urals. However, several manifestations, e.g., «Opytnyi» sector, which have not yet been placed under production, require substantiation of the strategies for their integrated development, which, in turn, requires gaining the reliable data on the content of graphite in carbon-containing rocks. A method for simultaneous determination of organic and native carbon in carbon-containing rocks using an ELTRA CW MULTIPHASE carbon and water analyzer is proposed. The method is based on the combustion of organic carbon (coal, shale) in a stream of oxygen at 550°C and native carbon (graphite) in the temperature range 550 – 1000°C with subsequent IR-spectroscopic determination of the content of gaseous carbon dioxide. The interfering effect of magnesium carbonate and calcium carbonate on the determination of organic and native carbon was taken into account in the calculations. The carbonate content was determined using a separate sample in a nitrogen flow by decomposition of magnesium carbonate at 550°C and calcium carbonate within a temperature range of 550 – 1000°C. The content of chemically bound water in the composition of the minerals of carbon-containing rocks, was determined simultaneously with carbon. The only one type of carbon — graphite — was observed in the studied samples of the carbon-containing rock from «Opytnyi». The different combustion capacity of graphite was revealed: some of the crystals almost completely burn out at a temperature below 800°C and others above 800°C, which suggests the presence of cryptocrystalline and explicit crystalline graphite in the rocks. The developed method is rapid and corresponds in accuracy to the method for native carbon determination ±0.27 C % – 0.01 C % developed and approved by the Research Council for Analytical Methods of Research (NSAM).

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