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.

Spectrophotometric determination of trace amounts of phosphate in water and soil

2012 ◽  
Vol 66 (12) ◽  
pp. 2653-2658 ◽  
Author(s):  
S. Ganesh ◽  
Fahmida Khan ◽  
M. K. Ahmed ◽  
P. Velavendan ◽  
N. K. Pandey ◽  
...  
Keyword(s):  
Environmental Science ◽  
Medical Science ◽  
Selective Reduction ◽  
Phosphomolybdic Acid ◽  
Molar Absorptivity ◽  
Ammonium Molybdate ◽  
Blue Colour ◽  
Molybdenum Blue ◽  
Relative Standard

A simple spectrophotometric method has been developed for the determination of phosphate dissolved in soil and water. The method is based on the formation of phosphomolybdate with added ammonium molybdate followed by reduction with hydrazine in acidic medium. Orthophosphate and molybdate ions condense in acidic solution to give molybdophosphoric (phosphomolybdic) acid, which upon selective reduction (perhaps with hydrazinium sulphate) produces a blue colour, due to molybdenum blue of uncertain composition. The intensity of blue colour is proportional to the amount of phosphate. If the acidity at the time of reduction is 0.5 M in sulphuric acid and hydrazinium sulphate is the reductant, the resulting blue complex exhibits maximum absorption at 830 nm. The system obeys Lambert–Beer's law at 830 nm in the concentration range of 0.5–5 μg/mL of phosphate with a relative standard deviation (RSD) of 0.1% and correlation coefficient of 0.99. Molar absorptivity was determined to be 2.9 × 104 L mol–1 cm–1 at 830 nm. The method is also applicable for the determination of phosphate in nuclear reprocessing plants, medical science, clinical science, agriculture, metallurgy and environmental science.

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).

scholarly journals Determination of reducing and total sugars in West Indian cherry (malpighia punicifolia, L.) juice

1969 ◽  
Vol 37 (3) ◽  
pp. 199-205
Author(s):  
Rafael Santini, Jr.
Keyword(s):  
Ascorbic Acid ◽  
Room Temperature ◽  
Reducing Sugars ◽  
Sugar Content ◽  
West Indian ◽  
Total Sugars ◽  
Total Sugar Content ◽  
Significant Difference ◽  
Cherry Juice

(1) Ascorbic acid is the substance responsible for the discrepancies found in the determination of reducing sugars and total sugars by the Lane-Eynon method. By correcting for ascorbic acid using the factor (F) 0.686, the discrepancy is eliminated and the Lane-Eynon method can be used. (2) To determine the total sugar content of West Indian cherry juice corrected reducing sugars only need be assayed, because it was proved experimentally and statistically that there is no significant difference between corrected reducing and corrected total sugars. (3) The sugar content of West Indian cherry juices stored at room temperature and at 45°F. does not change appreciably after 1 year. (4) At 45°F. ascorbic acid is lost less readily than at room temperature, but temperature produces no significant difference in the true sugar content of the juice.

Fabrication and Solid State Characterization of Ticagrelor Co-Crystals with Improved Solubility and DissolutionOptimization and Validation of Visible-Spectrophotometry Method For Determination Ascorbic Acid in Jeruk Bali (Citrus maxima) Fruit From Indonesia

2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Sudjarwo Sudjarwo
Keyword(s):  
Ascorbic Acid ◽  
Ammonium Molybdate ◽  
Instrumental Method ◽  
Blue Color ◽  
Citrus Maxima ◽  
Area Optimization ◽  
Instrumental Methods ◽  
Solid State Characterization

The method validation is prelimnary step in a research when researcher has not familier yet with the instruments, procedures and different sample matrices. The aim is obtaining suitable analytical method. Spectrophotometry is an instrumental method which is simpler, faster and cheaper than other instrumental methods. This study optimized and validated Spectrophotometry method for the determination of ascorbic acid in Jeruk Bali Fruit (Citrus maxima). Ascorbic acid in acidic condition gives blue color when was reacted with ammonium molybdate, then the absorbance was observed in visible wavelength area. Optimization to determine ascorbic acid (250.0 µg) required the addition of 4.0 ml of 5% sulphuric acid, 1.5 ml of 3% metaphosphate acid, 1.5 ml of 5% ammonium molybdate and the resulting color was stabil within 20-30 minutes. Furthermore, optimized condition was applied to validate Spectrophotometry method for the determination of ascorbic acid in Jeruk Bali Fruit. Selectivity test obtained 701 nm as wavelength of choice, linierity test resulted Y=0.0019x+0.071 and r=0.9998 (p=0.000; p0.01), Coeffisien of Variation (C.V)=0.3512%, recovery was (%) = 100.2128±1.7039. Using optimized and validated condition, the determination of ascorbic acid in Jeruk Bali Fruit from Indonesia =0.0208±0.0129 (%; w/w).

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

410. The oxidation of ascorbic acid in dairy products

1950 ◽  
Vol 17 (1) ◽  
pp. 54-65 ◽  
Author(s):  
J. E. Allan
Keyword(s):  
Ascorbic Acid ◽  
Cold Storage ◽  
Dairy Products ◽  
Room Temperature ◽  
Ferric Iron ◽  
Storage Temperature ◽  
Chloride Ion ◽  
Inhibitory Effect ◽  
Titration Procedure

1. The determination of ascorbic acid in butter by the usual macrotitration method was found to be impossible because this substance rapidly became oxidized while the butter was being melted, so that only about half could be recovered.2. A simple micro-titration procedure enabled more reliable results to be obtained, but the loss of ascorbic acid from smaller samples could not be reduced below about 10% under the most favourable conditions.3. Kinetic experiments have been carried out on butter serum and buttermilk to which ascorbic acid had been added, and from the results it has been deduced that the oxidation of ascorbic acid takes place by three distinct concomitant reactions: one catalysed by the original copper, one catalysed by added copper, and one catalysed by added ferric iron.4. It has been calculated that in an unsalted butter of normal metallic content half the ascorbic acid would be oxidized in about 12 hr. at cold storage temperature ( – 13° C). At this temperature, 0·1 p.p.m. of added copper is about twenty times as effective a catalyst as 1·0 p.p.m. of added iron. At room temperature the corresponding half-oxidation time would be about 2 hr., and here 0·1 p.p.m. of added copper is about four times as active as 1·0 p.p.m. of added iron. In salted butter the inhibitory effect of the chloride ion would increase these times somewhat.5. The chemical state in which copper and iron exist in milk and related products has been discussed, especially in relation to the kinetic results obtained.

scholarly journals The effect of selected substances on the stability of standard solutions in voltammetric analysis of ascorbic acid in fruit juices

2019 ◽  
Vol 17 (1) ◽  
pp. 655-662
Author(s):  
Radosław Kowalski ◽  
Artur Mazurek ◽  
Urszula Pankiewicz ◽  
Marzena Włodarczyk-Stasiak ◽  
Monika Sujka ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Room Temperature ◽  
Nutritive Value ◽  
Fruit Juices ◽  
Optimum Concentration ◽  
Voltammetric Analysis ◽  
The Stability ◽  
Standard Solutions

AbstractThe objective of the study was to identify suitable additives stabilizing standard solutions of ascorbic acid (AA) that would not cause interference in the analytical process with the use of voltammetry in the determination of the AA content in food products. In addition, the effect of various conditions of storage of selected fruit juices and drinks on the concentration of vitamin C was studied. The study demonstrated that AA degradation was inhibited the most effectively by tartaric acid and its optimum concentration was set to 200 mg L-1. Analysis of selected fruit juices stored in various temperature conditions confirmed that an elevation of temperature and extension of the time of storage caused a decrease in the content of vitamin C in the analyzed samples, while closing the packages caused a limitation of the changes in concentration of this vitamin. On the basis of literature data and of the results obtained in the present study it can be concluded that fruit juices should be stored at a temperature lower than room temperature to retain their nutritive value.

Sign in / Sign up

Export Citation Format

Share Document