Murexide indicator

Murexide Indicator. Suspend 0.5 g of powdered murexide in water, shake thoroughly, and allow the undissolved solid to settle. Use 5-6 drops of the supernatant liquid for each titration. Decant the old supernatant liquid daily and treat the residue with water to provide a fresh solution of the indicator. 

Procedure. Prepare the murexide indicator as described in Section 10.57(a), and an ammonium chloride solution (1M) by dissolving 26.75 g ammonium chloride in de-ionised water in a 500 mL graduated flask. 

Pipette 25.0 mL of the bromide ion solution (0.01-0.02M) into a 400 mL beaker, add excess of dilute silver nitrate solution, filter off the precipitated silver bromide on a sintered glass filtering crucible, and wash it with cold water. Dissolve the precipitate in a warm solution prepared from 15 mL of concentrated ammonia solution, 15 mL of 1M ammonium chloride, and 0.3 g of potassium tetracyanonickelate. Dilute to 100-200 mL, add three drops of murexide indicator, and titrate with standard EDTA (0.01 M) (slowly near the end point) until the colour changes from yellow to violet. 

Add 2 cm3 of NaOH solution (0.1 mol dm-3) to 50 cm3 of sample and titrate with EDTA using murexide indicator (Table 5.8). 

The 0.1M K2Ni(CN)4 soln is prepd by titrating 1 mole KCN dissolved in ca 500ml of w contg ammonia, with 0.1M NiS04 soln until murexide indicator(satd soln of Amm purpurate, made fresh daily) changes from yel to purple. Then the soln is diluted to 1 liter... 

As soon as contents of beakers are completely dissolved, the solns are diluted to ca 500ml and titrated, in presence of murexide indicator, with 0.1M disodium ethylene-diaminetetraacetate(EDTA) to chge of color from yel to purple. Each ml of 0.100M EDTA corresponds to I6.691mg CIO and 19.891mg CIO ... 

Murexide Indicator Preparation Add 400 mg of murexide to 40 g of powdered potassium sulfate (K2S04), and grind in a glass mortar to a homogeneous mixture. Alternatively, use tablets containing 0.4 mg of murexide admixed with potassium sulfate or potassium chloride, available commercially. 

Ca and Mg in water (water hardness) Ca determination Add 2 cm 3 of NaOH solution (0.1 mol dm 3) to 50 cm3 of sample and titrate with EDTA using murexide indicator (table 5.8). Mg determination Destroy murexide colour with 1 cm3 concentrated HQ add 3 cm3 of NH3—NH4C1 buffer and titrate with EDTA using eriochrome black T. 

Masking can be achieved by precipitation, complex formation, oxidation-reduction, and kinetically. A combination of these techniques may be employed. For example, Cu " can be masked by reduction to Cu(I) with ascorbic acid and by complexation with I . Lead can be precipitated with sulfate when bismuth is to be titrated. Most masking is accomplished by selectively forming a stable, soluble complex. Hydroxide ion complexes aluminum ion [Al(OH)4 or AlOa"] so calcium can be titrated. Fluoride masks Sn(IV) in the titration of Sn(II). Ammonia complexes copper so it cannot be titrated with EDTA using murexide indicator. Metals can be titrated in the presence of Cr(III) because its EDTA chelate, although very stable, forms only slowly. 

Solubility soluble in acetonitrile and many polar solvents. Analysis of Reagent Purity metal content determined by EDTA complexometry using a murexide indicator anion determination using acid cation exchange resin followed by titration of eluted acid with NaOH. ... 

APPLICATION OF A METAL ION/MUREXIDE INDICATOR SYSTEM TO THE STUDY OF MICELLAR PHENOMENA... 

METAL lON/MUREXIDE INDICATOR SYSTEM IN MICELLAR STUDY... 

---