Basic Fuchsin
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Benzenamine,4-[(4-aminophenyl)(4-imino-2,5-cyclohexadien-1-ylidene)methyl-2-methyl]-,monohydrochloride.
C.I.Basic Violet 14monohydrochloride [632-99-5].
»Basic Fuchsin is a mixture of rosaniline and pararosaniline hydrochlorides.It contains the equivalent of not less than 88.0percent of rosaniline hydrochloride (C20H19N3·HCl),calculated on the dried basis.
Packaging and storage—
Preserve in well-closed containers.
Identification—
A:
To 5mLof a solution (1in 1000)add a few drops of hydrochloric acid:a yellow color is produced (distinction from acid fuchsin).
B:
To 5mLof a solution (1in 500)add a few drops of tannic acid TS:a red precipitate is formed.
C:
To 10mLof a solution (1in 500)add 10mLof ammonia TSand 500mg of zinc dust,and agitate the mixture:the solution becomes decolorized.Place a few drops of the decolorized solution on filter paper,and nearby on the same paper place a few drops of 3Nhydrochloric acid:a red color develops at the zone of contact.
Loss on drying á731ñ—
Dry it at 105
to constant weight:it loses not more than 5.0%of its weight.
to constant weight:it loses not more than 5.0%of its weight.
Residue on ignition á281ñ—
Ignite 1g with 0.5mLof sulfuric acid:the weight of the residue is not more than 0.3%.
Alcohol-insoluble substances—
Boil 1g,accurately weighed,with 50mLof alcohol under a reflux condenser for 15minutes,filter through a tared filtering crucible,wash the residue on the filter with hot alcohol until the washings cease to be colored violet,and dry the crucible at 105for 1hour:the amount of insoluble residue is not more than 1.0%.
for 1hour:the amount of insoluble residue is not more than 1.0%.
Arsenic,Method IIá211ñ:
8ppm.
Lead á251ñ:
Place 1g in a small Kjeldahl flask,add 5mLof sulfuric acid,and insert a small funnel into the flask.Gently rotate the flask until the sulfuric acid has completely wetted the Basic Fuchsin,then heat with a small flame until carbonization is complete.Allow to cool,and add,in small quantities,5mLof nitric acid.Again heat gently until fumes of sulfur trioxide are evolved.Allow to cool,add another 5mLof nitric acid,and heat to the evolution of sulfur trioxide.Allow to cool,add about 25mLof water,and boil for a few minutes.Cool,neutralize with stronger ammonia water,using litmus paper as the indicator,and add 5mLof nitric acid.Transfer the solution to a 100-mLvolumetric flask,dilute to volume,and mix.A20-mLportion of this solution contains not more than 30ppm of lead.
Assay—
Dissolve about 100mg of Basic Fuchsin,accurately weighed,in 175mLof water in a 500-mLclosed system titration vessel fitted with a gas inlet tube,a gas outlet tube,an upright reflux condenser,and a buret.Add about 25mLof sodium tartrate solution (30in 100)and a polytef-coated magnetic stirring bar,and heat to boiling.Flush this titration vessel for 15minutes with nitrogen that has been passed through two successive gas washing bottles each containing 500mLof a mixture of water,titanium trichloride solution (20in 100),and hydrochloric acid (400:40:40)to which about 10mg of safranin Ohas been added.Continue the heating and nitrogen flow,and while stirring titrate with 0.05Ntitanium trichloride VSto a yellow endpoint.Each mLof 0.05Ntitanium trichloride is equivalent to 3.379mg of C20H19N3·HCl.
Auxiliary Information—
Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 874
Phone Number:1-301-816-8251