A New Simple Semimicro Method for Colorimetric Determination of Urea

1963 ◽  
Vol 9 (1) ◽  
pp. 102-108 ◽  
Author(s):  
J J Coulombe ◽  
L Favreau
Keyword(s):  
Acid Medium ◽  
Rapid Method ◽  
Room Temperature ◽  
Colorimetric Determination ◽  
Red Color ◽  
Color Complex ◽  
Blood Filtrate ◽  
Diacetyl Monoxime

Abstract A new simple and rapid method for quantitative semimicro determination of blood urea is presented. Diacetyl monoxime and thiosemicarbazide form in acid medium with urea a red color complex with a maximum adsorption at 530 mµ stable at room temperature and requiring 0.2 ml. of 1:10 blood filtrate.

Colorimetric Determination of Carbaryl in Apple, Lettuce, Chard, and Tomato

1971 ◽  
Vol 54 (5) ◽  
pp. 1083-1085
Author(s):  
Maria H C K De Riveros ◽  
Eugenio E Vonesch
Keyword(s):  
Methylene Chloride ◽  
Zinc Hydroxide ◽  
Colorimetric Determination ◽  
Color Complex

Abstract A direct Spectrophotometric technique for determination of carbaryl in apple, lettuce, chard, and tomato has been developed, based on formation of a specific color complex with diazotized 2,5-dichloroaniline sulfate. Carbaryl is extracted with methylene chloride, concentrated, and cleaned up with zinc hydroxide. The color produced with diazotized 2,5-dichloroaniline is measured at 510 nm. Recoveries of added carbaryl from the 4 crops tested ranged from 89.6 to 105%.

Colorimetric determination of urea v2

2021 ◽  
Author(s):  
noah.langenfeld not provided ◽  
Laurenpayne not provided ◽  
Bruce Bugbee
Keyword(s):  
Colorimetric Determination ◽  
Diacetyl Monoxime

This protocol measures the absorbance of urea in solution in complexation with diacetyl monoxime at 520 nm and is linearly proportional to concentration up to 5 mM urea.

Continuous-flow determination of serum inorganic phosphate with a single reagent--the vanadomolybdate method re-evaluated.

1977 ◽  
Vol 23 (7) ◽  
pp. 1275-1280 ◽  
Author(s):  
H Baadenhuijsen ◽  
H E Seuren-Jacobs ◽  
A P Jansen
Keyword(s):  
Acid Medium ◽  
Inorganic Phosphate ◽  
Room Temperature ◽  
Visible Range ◽  
Color Development ◽  
Optimum Reaction ◽  
The Stability ◽  
Serum Inorganic Phosphate ◽  
Tungsten Lamp

Abstract The merits of the vanadomolybdate method in the determination of inorganic phosphate are highly underestimated with regard to the simplicity of the method and the stability of both the reagents and the color that is formed. The absorption curve of the phosphovanadomolybdate complex, with its maximum at 335 nm, extends into the visible range of the spectrum. This permits measurements with inexpensive tungsten-lamp colorimeters. On-stream dialysis is best done in a nitric acid medium, 0.15 mol/liter. Paralleled by the change in the H2PO4-/H3PO4 ratio, appreciable protein binding and poor dialysis efficiency are seen at lower acid concentrations (pH greater than 1.0). Optimum reaction-mixture concentrations of vanadium and molybdenum appeared to be respectively 0.2 and 5 mmol/liter up to 3 mmol of phosphate per liter, in a final acid medium of 0.2 mol/liter, concentrations considerably lower than those used in some studies published earlier. Color development with the stable combined reagent is complete after only 20 s at room temperature and the color is stable for at least 2 h. Figures on precision and accuracy demonstrate the reliability of the method.

Determination of Guthion® Residues on Fruits

1963 ◽  
Vol 46 (2) ◽  
pp. 229-233
Author(s):  
William S Cox
Keyword(s):  
Rapid Method ◽  
Close Agreement ◽  
Fruits And Vegetables ◽  
Collaborative Study ◽  
Colorimetric Determination ◽  
Citrus Fruits ◽  
Upper Level

Abstract The 1962 collaborative study consisted of the colorimetric determination of Guthion residues on locally purchased apples and grapes. Each fruit was “spiked” at levels of 1 and 3 ppm. Six of eight collaborators obtained recoveries of 80—106% at the lower level, and 95-111% at the upper level. Blanks were consistently low, and duplicate results were in close agreement. The method, adopted in 1960 for coletype crops, is being recommended for adoption for non-citrus fruits. Several changes in wording are recommended to clarify and shorten the method. A rapid method, based on benzene stripping of fresh fruits and vegetables, followed by cleanup with acetonitrile-n-hexane partitioning, is recommended for collaborative study next year.

scholarly journals Second-Derivative Spectrometric Determination of Urea in Milk Using the Diacetyl Monoxime Reagent

2010 ◽  
Vol 93 (2) ◽  
pp. 485-491 ◽  
Author(s):  
Steven A Nyanzi ◽  
Maureen Isiko ◽  
Francis Kateregga ◽  
Wolfgang Schwack
Keyword(s):  
Correlation Coefficients ◽  
Colorimetric Determination ◽  
Second Derivative ◽  
Linear Calibration ◽  
Colored Complex ◽  
Spectral Bands ◽  
Sensitivity And Selectivity ◽  
Diacetyl Monoxime ◽  
Second Derivative Method

Abstract The application of derivative spectrometry to resolve overlapping spectra and improve the sensitivity and selectivity of the colorimetric determination of urea in milk using diacetyl monoxime is presented. With first-derivative (1D) spectrometry, the max of the colored complex was established to be 525 nm. The absorption band at max 525 nm in normal absorption (0D) spectrometry was resolved into three clearly distinct spectral bands with minima at 497, 530, and 566 nm with second-derivative (2D) spectrometry. With the second-derivative (2D530) technique, the depth of the trough of the strongest signal at 530 nm was used to determine urea in milk samples. Linear calibration curves for urea were obtained over a concentration range of 0.21.4 mg/L, with correlation coefficients greater than 0.999. The LOD and LOQ of the method were 0.01 and 0.03 mg/L, respectively. Recoveries of 99100 of spiked urea in milk with RSD values below 2.0 were obtained. The second-derivative method is simple, affordable, sensitive, and selective for the determination of urea in milk.

Colorimetric Determination of Alkaline Phosphatase as Indicator of Mammalian Feces in Corn Meal: Collaborative Study

1986 ◽  
Vol 69 (3) ◽  
pp. 496-498
Author(s):  
Harriet Gerber ◽  
◽  
B Beavin ◽  
S Brown ◽  
J Bryce ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Agar Medium ◽  
Collaborative Study ◽  
Official Method ◽  
Colorimetric Determination ◽  
Corn Meal ◽  
Small Particles ◽  
Red Color ◽  
Repeatability And Reproducibility

Abstract In the official method for rodent filth in corn meal, filth and corn meal are separated in organic solvents, and particles are identified by the presence of hair and a mucous coating. The solvents are toxic, poor separation yields low recoveries, and fecal characteristics are rarely present on all fragments, especially on small particles. The official AOAC alkaline phosphatase test for mammalian feces, 44.181-44.184, has therefore been adapted to determine the presence of mammalian feces in corn meal. The enzyme cleaves phosphate radicals from a test indicator/substrate, phenolphthalein diphosphate. As free phenolphthalein accumulates, a pink-to-red color develops in the gelled test agar medium. In a collaborative study conducted to compare the proposed method with the official method for corn meal, 44.049, the proposed method yielded 45.5% higher recoveries than the official method. Repeatability and reproducibility for the official method were roughly .1.8 times more variable than for the proposed method. The method has been adopted official first action.

The colorimetric determination of cyanate ion with hydroxylamine-diacetyl monoxime

1974 ◽  
Vol 23 (9) ◽  
pp. 1071-1073
Author(s):  
Keiichiro ISHII ◽  
Takeji IWAMOTO ◽  
Kazuhiko YAMANISHI
Keyword(s):  
Colorimetric Determination ◽  
Diacetyl Monoxime

A simple and rapid method for colorimetric determination of histamine in fish flesh

Food Control ◽  
2005 ◽  
Vol 16 (5) ◽  
pp. 465-472 ◽  
Author(s):  
S.B. Patange ◽  
M.K. Mukundan ◽  
K. Ashok Kumar
Keyword(s):  
Rapid Method ◽  
Colorimetric Determination ◽  
Fish Flesh

Colorimetric Determination of Bismuth in Bismuth Subsalicylate Oil Suspension

1963 ◽  
Vol 46 (4) ◽  
pp. 649-651
Author(s):  
Salvatore J Pinella
Keyword(s):  
Sesame Oil ◽  
Colorimetric Determination ◽  
Final Solution ◽  
Bismuth Subsalicylate ◽  
Thiourea Complex ◽  
Ether Extraction ◽  
Thiourea Solution ◽  
Color Complex ◽  
Official Methods Of Analysis

Abstract A study was made of a colorimetric determination of bismuth in bismuth subsalicylate oil suspension, similar to that of Official Methods of Analysis. The method depends upon the formation of a yellow bismuth-thiourea complex which exhibits maximum absorption at 465 mμ. Sesame oil is removed by ether extraction after HNO3 hydrolysis and the bismuth nitrate formed is converted to bismuth-thiourea complex with 2.5% thiourea solution in HNO3 (1 + 9). The color complex is stable and follows Beer’s law. The method is comparatively specific for bismuth, since only vanadium and antimony give similar color. It is satisfactory at concentrations as low as 50 μg of bismuth in the final solution. Nine collaborators reported favorable results; it is recommended that the method be adopted as official, first action.

scholarly journals Sensitive spectrophotometric methods for determination of some organophosphorus pesticides in vegetable samples

2010 ◽  
Vol 16 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Ayman Gouda ◽  
Alaa Amin ◽  
Ragaa El-Sheikh ◽  
Magda Akl
Keyword(s):  
Acid Medium ◽  
Organophosphorus Pesticides ◽  
Molar Absorptivity ◽  
Accurate Analysis ◽  
Spectrophotometric Methods ◽  
Vegetable Samples ◽  
Hydrochloric Acid Medium ◽  
Red Color ◽  
Chromotrope 2R

Three rapid, simple, reproducible and sensitive spectrophotometric methods (A, B and C) are described for the determination of two organophosphorus pesticides, (malathion and dimethoate) in formulations and vegetable samples. The methods A and B involve the addition of an excess of Ce4+ into sulphuric acid medium and the determination of the unreacted oxidant by decreasing the red color of chromotrope 2R (C2R) at a suitable ?max = 528 nm for method A, or a decrease in the orange pink color of rhodamine 6G (Rh6G) at a suitable ?max = 525 nm. The method C is based on the oxidation of malathion or dimethoate with the slight excess of N-bromosuccinimide (NBS) and the determination of unreacted oxidant by reacting it with amaranth dye (AM) in hydrochloric acid medium at a suitable ?max = 520 nm. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.1-4.2 ?g mL?1. The apparent molar absorptivity, Sandell sensitivity, the detection and quantification limits were calculated. For more accurate analysis, Ringbom optimum concentration ranges are 0.25-4.0 ?g mL?1. The developed methods were successfully applied to the determination of malathion, and dimethoate in their formulations and environmental vegetable samples.

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