scholarly journals Standardization of a colorimetric method for the determination of fructose using o-cresol: Sulphuric acid reagent

1997 ◽  
Vol 12 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Vishu Kumar ◽  
T. N. Pattabiraman
Keyword(s):  
Sulphuric Acid ◽  
Colorimetric Method ◽  
Acid Reagent

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.

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.

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).

Colorimetric Method for Determination of Ethanol in Presence of Methanol

1981 ◽  
Vol 64 (5) ◽  
pp. 1145-1148
Author(s):  
Ramesh T Sane ◽  
Sudhir S Kamat ◽  
Amulya D Pandit
Keyword(s):  
Colorimetric Method ◽  
Thiobarbituric Acid ◽  
Normal Value ◽  
Beer's Law ◽  
Acid Reagent ◽  
Beer’S Law

Abstract A method is described for the determination of ethanol in the presence of methanol without pre-separation. The sample is oxidized to give acetaldehyde and formaldehyde. 2-Thiobarbituric acid reagent is added and selectively forms a pink adduct with acetaldehyde, but not with formaldehyde. The method is sensitive, obeys Beer’s law in the concentration range 18–80 μg/mL, and has an advantage over other methods because it does not detect any “apparent normal value” of alcohol in blood.

scholarly journals A Sulphuric Acid Reagent for the Colori-metric Determination of Testosterone

Nature ◽  
1964 ◽  
Vol 201 (4916) ◽  
pp. 296-296 ◽  
Author(s):  
LOTHAR SACHS
Keyword(s):  
Sulphuric Acid ◽  
Acid Reagent

Ferrous iron-sulphuric acid reagent for the determination of pure œstrogens

Talanta ◽  
1959 ◽  
Vol 2 (2) ◽  
pp. 183-186 ◽  
Author(s):  
Emanuel Epstein ◽  
William O. Maddock ◽  
A.J. Boyle
Keyword(s):  
Sulphuric Acid ◽  
Ferrous Iron ◽  
Acid Reagent

Toxicologic Studies on Hydrocarbons. VI. A Colorimetric Method for the Determination of Kerosine in Blood

1960 ◽  
Vol 6 (4) ◽  
pp. 327-331 ◽  
Author(s):  
Horace W Gerarde ◽  
Paul Skiba
Keyword(s):  
Sulfuric Acid ◽  
Carbon Tetrachloride ◽  
Quantitative Determination ◽  
Calibration Curve ◽  
Colorimetric Method ◽  
Acid Reagent

Abstract A photoelectric colorimetric method is described for the quantitative determination of kerosine in blood. The procedure involves hemolysis of 5 ml. of the sample followed by extraction of the kerosine with carbon tetrachloride. The extract is reacted with a formaldehyde- sulfuric acid reagent to produce a characteristic color. The intensity of this color is measured photometrically, and the concentration of kerosine is determined by reference to a previously prepared calibration curve. Concentrations as low as 10 ppm can be conveniently determined.

Amines in Fish Muscle: I. Colorimetric Determination of Trimethylamine as the Picrate Salt

1945 ◽  
Vol 6d (5) ◽  
pp. 351-358 ◽  
Author(s):  
W. J. Dyer
Keyword(s):  
Picric Acid ◽  
Colorimetric Method ◽  
Fish Muscle ◽  
Colorimetric Determination ◽  
Acid Reagent ◽  
Fishery Products

A sensitive accurate colorimetric method for trimethylamine determination is presented, based on the extraction with toluene of an alkaline sample containing 0.002 to 0.02 mg. trimethylamine nitrogen, and the formation of the yellow coloured picrate by mixing with a picric acid reagent. The application of the method in fishery products and effects of interfering substances have been investigated.

Sign in / Sign up

Export Citation Format

Share Document