Of color reagents

After refluxing, disconnect the trapping tube, and transfer the yellow solution into a 25-mL volumetric flask. Rinse the mbe with ethanol, and adjust the solution to volume with ethanol. Measure the absorbance of the solution at 435 nm against a blank prepared by diluting 15 mL of color reagent to 25 mL with ethanol. Determine the carbon disulflde content from a calibration curve obtained by plotting carbon disulfide concentrations of different standard solutions on the abscissa versus the absorbance on the ordinate. 

Add 2 drops of color reagent. Compare color produced with reference compounds on spot plate or other white porcelain surface. 

To 50 mL of solution passed through cadmium column, add 2 mL of color reagent and mix. Allow the solution to stand for 30 min Measure the absorbance at 543 nm against a distilled water-reagent blank. Read the concentration of N03 -N from the prepared standard curve. Standards should be reduced exactly like samples. 

Prepare reagent solutions add 10 ml solvent A into one vial of color reagent A and mix gently. Add 20 ml solvent B into one vial of color reagent B and mix gently. Solvent A and B solutions are stable at 2-10°C for 5 days. 

Standard Curve Pipet 5 mL of the Hydroxyproline Standard Solution into a 500-mL volumetric flask, and dilute to volume with water. Prepare this solution on the day of use. Pipet 10-, 20-, 30-, and 40-mL volumes of the solution into separate 100-mL volumetric flasks, and dilute each to volume with water. These solutions contain 0.6, 1.2, 1.8, and 2.4 jxg/ mL of hydroxyproline, respectively, and must be prepared on the day of use. Transfer 2.0 mL of each solution into four separate test tubes, and 2.0 mL of water into a fifth tube to use as a blank. Add 1.0 mL of Oxidant Solution to each tube, shake, and let stand for about 30 min. Add 2.0 mL of Color Reagent to each tube, mix thoroughly, cap the tubes with foil or screw caps, and place them in a water bath at 60° 0.5° for exactly 15 min. Cool the tubes in running water for 3 min, and dry the outside of the tubes. Measure the absorbance of each solution against the blank in 10-mm glass cells, using an appropriate spectrophotometer, at 558 nm. Draw a standard... 

There are a great number of color reagents for copper, some of which are listed in Table 1. Their relative sensitivity can be compared on the basis of their molar absorbancy indices. The references given in the last column of Table 1 pertain to the sensitivity, specificity, and general charac-... 

Hydantoin itself can be detected ia small concentrations ia the presence of other NH-containing compounds by paper chromatography followed by detection with a mercury acetate—diphenylcarba2one spray reagent. A variety of analytical reactions has been developed for 5,5-disubstituted hydantoias, due to their medicinal iaterest. These reactions are best exemplified by reference to the assays used for 5,5-diphenylhydantoiQ (73—78), most of which are based on their cycHc ureide stmcture. Identity tests iaclude the foUowiag (/) the Zwikker reaction, consisting of the formation of a colored complex on treatment with cobalt(II) salts ia the presence of an amine (2) formation of colored copper complexes and (3) precipitation on addition of silver(I) species, due to formation of iasoluble salts at N. ... 

Amino-4,6-dinitropheno1 is an important intermediate in the manufacture of colorants, especially mordant dyes. It has also been used as an indicator dye in titrations (yellow with acid, red with alkali) and as a reagent for albumin deterrnination. 

The complexes on surface of chelate-functionalized silica often include ligands available in solution in the coordination sphere. Use of a chromophore reagent as a ligand leads to the formation of colored mixed ligand complexes (MLC). The phenomena can be used as a basis for developing test-systems for visual determination of microquantities of inorganic cations in water. 

For determining the BDI value, 30 mL of milk was boiled for 15 min with 8.9 mL of BDI reagent. 0.25 g of the separated fat was put in a titration tube with 5 mL BDI titration medium. Titration was performed with tetra-n-butyl ammonium hydroxide until the color of the medium changed. 

PHOTOMETRIC DETERMINATION OF ACIDIC IMPURITIES IN OILS AND ORGANIC LIQUIDS WITH THE USE OF THE ION PAIR OF TRINONYLOCTADECYLAMMONIUM AND BROMOTHYMOL BLUE AS THE COLORED REAGENT... 

Treatment of the chromatogram with a reagent results in the production of colored or fluorescent chromatogram zones, which are used to evaluate the success of the separation and for quantitative analysis For this purpose it is necessary that the color or fluorescence intensities remain stable for about 30 minutes... 

---