scholarly journals The determination of silicate in sea water

1951 ◽  
Vol 30 (1) ◽  
pp. 149-160 ◽  
Author(s):  
F. A. J. Armstrong
Keyword(s):  
Sulphuric Acid ◽  
Sea Water ◽  
Picric Acid ◽  
Colorimetric Method ◽  
Ammonium Molybdate ◽  
Potassium Chromate ◽  
Distilled Water ◽  
Yellow Colour ◽  
Standard Solutions

Silicon in sea water may be present in suspension, in particles of clay or sand, as a constituent of diatoms, etc., or in solution. Some silicon in solution occurs in the form of silicate. This is usually estimated by the colorimetric method of Diénert & Wandenbulcke (1923), which makes use of the yellow colour of the silicomolybdic acid which is formed when ammonium molybdate and sulphuric acid are added to the water (Atkins, 1923). The colour may be compared with that of standard solutions of picric acid (Diénert & Wandenbulcke, 1923) or potassium chromate (Swank & Mellon, 1934). The method is simple but the colour in sea water is often faint and is not easy to match visually, nor is its intensity strictly proportional to the concentration of silicate. Less colour is produced in sea water than in standard solutions made with distilled water and this ‘salt error’ must be allowed for (Brujewicz & Blinov, 1933; Wattenberg, 1937; Robinson & Spoor, 1936).

Determination of nitrate in sea water by cadmium-copper reduction to nitrite

1967 ◽  
Vol 47 (1) ◽  
pp. 23-31 ◽  
Author(s):  
E. D. Wood ◽  
F. A. J. Armstrong ◽  
F. A. Richards
Keyword(s):  
Standard Deviation ◽  
Sulphuric Acid ◽  
Sea Water ◽  
Colorimetric Method ◽  
Zinc Powder ◽  
Small Samples ◽  
Nitrosyl Chloride ◽  
Sensitivity Limit ◽  
High Concentrations

An accurate, dependable determination of 0–60 μg-at./l. of NO−3-N in sea water has been developed. The sample is treated with tetrasodium ethylenediaminetetraacetate solution and passed through a column of copperized cadmium filings. A nearly quantitative reduction of nitrate to nitrite results. Nitrite is then determined by a diazotization method. Neither sulphide nor high nitrite concentrations interferes. Approximately eight samples per hour per column can be analysed with a standard deviation of 0.12 μg-at./l. at the 20 μg-at./l. level.IntroductionAccurate determinations of nitrate ions in sea water have been difficult, especially under shipboard conditions.The colorimetric method described by Harvey (1926, 1930) and improved by Cooper (1932), Zwicker & Robinson (1944), and others uses strychnidine in concentrated sulphuric acid to produce a red colour. The reagent lacks reliable sensitivity, because it is dependent on the rates of mixing and cooling.In a method by Armstrong (1963), the absorbance of nitrosyl chloride in the UV region is measured with a spectrophotometer. While the method is good for small samples containing high concentrations of nitrate, the use of concentrated sulphuric acid and lack of sensitivity limit its use in routine analysis.A method in which nitrate is quantitatively reduced to nitrite would be advantageous, because nitrite can be readily determined by the sensitive diazotization method proposed by Griess (1879). Several such methods have been proposed. FØyn (1951), Vatova (1956), and Chow & Johnstone (1962) used zinc powder for the reduction, but the reduction is sensitive to temperature, and it is necessary to centrifuge or filter each sample.

THE DETERMINATION OF SMALL AMOUNTS OF FLUORINE IN WATER

1940 ◽  
Vol 18b (6) ◽  
pp. 151-159 ◽  
Author(s):  
Osman James Walker ◽  
Gordon Roy Finlay
Keyword(s):  
Sulphuric Acid ◽  
Perchloric Acid ◽  
Colorimetric Method ◽  
Fluorine Content ◽  
Sodium Ions ◽  
Ferric Ions ◽  
Titration Method

In the survey of Alberta waters in which fluorine content is compared with the prevalence of mottled teeth, the titration method and the colorimetric method for determining fluorine have not always given comparable results. Good results with the titration method are obtained when distillation is carried out with perchloric acid instead of with sulphuric acid. It was found that the colorimetric method is affected by more than 2 p.p.m. of phosphate, aluminium, or ferric ions, and by over 120 p.p.m. of sulphate ions. Moderate amounts of manganous, ferrous, silicate, chloride, and sodium ions do not interfere. When the water contains over 2 p.p.m. of phosphate, aluminium, or ferric ions, or if the water is coloured, the titration method is used. A scheme for correcting for sulphate ions is proposed. The titration method and the colorimetric method used in this laboratory for determining fluorine in waters are given in detail.

Colorimetric Determination of Cyanide Liberated from Apricot Kernels

1977 ◽  
Vol 60 (4) ◽  
pp. 954-956 ◽  
Author(s):  
Keith L Egli
Keyword(s):  
Hydrogen Cyanide ◽  
Steam Distillation ◽  
Sodium Hydroxide Solution ◽  
Picric Acid ◽  
Colorimetric Method ◽  
Potassium Cyanide ◽  
Colorimetric Determination ◽  
Apricot Kernels ◽  
Aoac Method

Abstract A simple colorimetric method is described for determining the quantity of hydrogen cyanide produced by the spontaneous decomposition of amygdalin in apricot kernels. The evolved cyanide is collected in sodium hydroxide solution and assayed colorimetrically by reaction with picric acid. Results for duplicate assays, 3.02 and 3.06 mg CN-/g, compare well with those obtained by AOAC method 26.115 which specifies steam distillation and silver nitrate titration; results for triplicate assays were 3.02, 3.03, and 3.08 mg CN-/g by the latter. Recovery of cyanide from potassium cyanide at a level equivalent to 243 μg CN-/g was 101.0%.

Method for determination of hydrogen peroxide, with its application illustrated by glucose assay.

1980 ◽  
Vol 26 (5) ◽  
pp. 658-660 ◽  
Author(s):  
E Graf ◽  
J T Penniston
Keyword(s):  
Hydrogen Peroxide ◽  
Colorimetric Method ◽  
Ammonium Molybdate ◽  
Analyte Concentration ◽  
Glucose Assay ◽  
Color Development ◽  
Iodine Complex ◽  
Biological Compounds ◽  
Illustrative Application

Abstract We describe a simple colorimetric method for determining micromolar quantities of hydrogen peroxide, based on the oxidation of iodide in the presence of ammonium molybdate and photometry of the resulting blue starch-iodine complex. Color development is linearly dependent on analyte concentration, but only slightly time dependent, and the color of the complex formed is stable for several hours. In the range of wavelengths that may be used (570 to 630 nm), lack of interference from other biological compounds makes this method seem suitable for routine analyses. As one illustrative application of the method we quantitated glucose by measuring hydrogen peroxide produced from it by glucose oxidase catalysis. This method of quantitating glucose is more than five times as sensitive as the commonly used dianisidine method. With the appropriate hydrogen peroxide-producing oxidases, this method may be used to directly measure amino acids, purines, uric acid, xanthine, and hypoxanthine.

scholarly journals The specific conductivity of solutions of oxyhæmoglobin

1912 ◽  
Vol 85 (580) ◽  
pp. 413-414 ◽  
Keyword(s):  
Royal Society ◽  
Specific Conductivity ◽  
Colorimetric Method ◽  
Relative Volume ◽  
Distilled Water

When preparing a paper on the mechanism of hæmolysis two or three years ago my attention was accidentally called to a statement in a paper by the late Prof. A. Gamgee in the ‘Proceedings’ of the Royal Society, that “although solutions of oxyhæmoglobin possess a low conductivity this is very much higher than has been found in the previous observations of Stewart.” In a note appended to my paper I suggested that this could only mean “that either his (Gamgee’s) oxyhæmoglobin or his distilled water was less thoroughly freed from electrolytes than mine. In observations of this kind the error must appear as too high and not as too low a conductivity.” Prof. Gamgee having laid stress on the purity of his distilled water and oxyhæmoglobin, this result seemed very puzzling, all the more as my object in determining the conductivity of some specimens of oxyhæmoglobin was merely to control their suitability for addition to blood in the determination of the relative volume of corpuscles and plasma by a colorimetric method described in the paper, and no such effort has been made to carry the exclusion of foreign electrolytes to the practically possible limit as would have been deemed indispensable had the conductivity of hæmoglobin been investigated for its own sake.

scholarly journals A Single-Solution Method for the Determination of Soluble Phosphate in Sea Water

1958 ◽  
Vol 37 (1) ◽  
pp. 9-14 ◽  
Author(s):  
J. Murphy ◽  
J. P. Riley
Keyword(s):  
Ascorbic Acid ◽  
Room Temperature ◽  
Solution Method ◽  
Sea Water ◽  
Ammonium Molybdate ◽  
Soluble Phosphate ◽  
Blue Colour ◽  
Molybdenum Blue ◽  
Single Solution

It has been found that a reagent containing sulphuric acid, ammonium molybdate and ascorbic acid may be used as a single-solution reagent for the determination of phosphate in sea water. Development of the molybdenum-blue colour is complete in 24 h at room temperature and in 30 min at 60° C; the colour is stable for at least 3 days. Beer's law is obeyed closely up to at least 500 μg PO43−-P/1. The salt error is approximately 4% with sea water of chlorinity 19·3%. The interference due to either arsenate or silicate at their concentrations in sea water is negligible.

scholarly journals Spectrophotometric Determination of Phosphate in Sugarcane Juice, Fertilizer, Detergent and Water Samples by Molybdenum Blue Method

2013 ◽  
Vol 11 (11) ◽  
pp. 58-62 ◽  
Author(s):  
Samjhana Pradhan ◽  
Megh Raj Pokhrel
Keyword(s):  
Hydrazine Hydrate ◽  
Sulphuric Acid ◽  
Ammonium Molybdate ◽  
Sugarcane Juice ◽  
Reaction Conditions ◽  
Molybdenum Blue ◽  
Scientific World ◽  
Coloured Complex ◽  
Phosphomolybdenum Blue

A simple and sensitive spectrophotometric method has been developed for the determination of phosphate in mg per liter (parts per million) concentration range in sugarcane juice, water, fertilizer and detergent samples. The amount of phosphate is determined by molybdenum blue phosphorus method in conjugation with UV-visible spectrophotometer. This method is based on the formation of phosphomolybdate complex with the added molybdate followed by the reduction of the complex with hydrazine hydrate in aqueous sulphuric acid medium. The system obeys Lambert-Beer’s law at 840 nm in the concentration range 0.1-11 ppm. The colour intensity of the reduced phosphomolybdate solution is found to be proportional to the amount of phosphate present in sugarcane juice, water, fertilizer and detergent samples. The reaction conditions as well as the various experimental parameters affecting the development and stability of the coloured complex were carefully investigated and optimized for the quantitative determination of phosphate present in various samples. The optimized concentrations of various reagents used are 0.20N sulphuric acid, 0.02M hydrazine hydrate and 0.20% ammonium molybdate. The effect of time on the formation of phosphomolybdenum blue complex and addition of the order of the reagents was also studied. Scientific World, Vol. 11, No. 11, July 2013, page 58-62DOI: http://dx.doi.org/10.3126/sw.v11i11.9139

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