This method applies to estimating Phenolic content in Perfume Premixes as well as Bar soap. determination of Total Phenolic Content.
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Principle
Phenolic compounds are extracted from perfume premixes/soap using alcohol and H2O mixture. A color complex is prepared by adding
4-aminophenazone solution & Potassium Ferricyanide in the presence of Borax solution,
which is then measured at 535 nm using a spectrophotometer against a standard
solution.
ReagentsÂ
(a) 4-Aminophenazone solution - 1% w/w aqueous
solution, freshly prepared.
(b) Potassium Ferricyanide - 2% w/w aqueous solution,
freshly prepared.
(c) Borax solution - 2% w/w aqueous solution.
(d) Isopropyl Alcohol (Isopropanol)
(e) Dilute Isopropanol solution - 30% v/v aqueous solution of Isopropyl alcohol in distilled water.
Total Phenolic Content Procedure
Preparation of standard premix solution (for soaps containing
TCC) - Dissolve 0.225 gm (accurately weighed) of standard Perfume Premix in 50
ml of isopropyl alcohol. Add 0.09 g of TCC to it, dissolve, and make up the volume
to 100 ml with isopropyl alcohol.
Transfer 5 ml of the above solution to a 100 ml volumetric
flask and make up the volume to 100 ml with dilute isopropyl alcohol. Mark the
solution "A".
Preparation of standard premix solution (for perfume
premixes) - Dissolve 0.225 gm (accurately weighed) of standard Perfume Premix
in 50 ml of isopropyl alcohol. Dissolve and make up the volume to 100 ml with isopropyl
alcohol.
Transfer 5 ml of the above solution to a 100 ml volumetric
flask and make up the volume to 100 ml with dilute isopropyl alcohol. Mark the solution
"A".
Preparation of sample solution (Bar soap) - Weigh accurately 0.5 g of fine shavings from the soap cake and dissolve in about 25 ml of dilute isopropyl alcohol, if necessary with the aid of gentle heat. Transfer the solution quantitatively to a 100 ml volumetric flask after cooling and make up the volume to 100 ml with dilute isopropyl alcohol. Mix well. Filter the solution through a dry GF/C or No. 40 Whatman filter paper into a dry flask rejecting the first few ml. of filtrate. Mark the solution "B".
Preparation of perfume premix sample solution - Dissolve
0.225 gm (accurately weighed) of sample Perfume Premix in 50 ml of dilute
isopropyl alcohol. Dissolve and make up the volume to 100 ml with dilute
isopropyl alcohol.
Transfer 5 ml of the above solution to a 100 ml volumetric
flask and make up the volume to 100 ml with dilute isopropyl alcohol. Mark the
solution "B".
Colour Development
- Place 20 ml of 2% w/v borax solution into each of two 50
ml volumetric flasks.
- Add 5 ml of solution "A" to one and 5 ml of
solution "B" to the other, and mix well.
- Add to each of the flasks 1 ml of 4 aminophenazone
solution and mix.
- Add 20 ml of 30% v/v isopropyl alcohol to each of the
flasks and mix.
- Add 1 ml of potassium ferricyanide solution and mix.
Make up the volume to 50 ml with 30% v/v isopropyl alcohol.
Determine the absorbance of the standard and sample in a 1 cm cell at the
wavelength of maximum absorption of about 535 nm, using water as a reference.
Calculation of phenolic content:
Phenolic content % w/w (for India)
Absorbance of sample  Â
 Standard Premix taken in g 23.28
= ---------------------------- x
--------------------------------- x --------- x 5
Absorbance of standard       Sample taken in g 100
Phenolic content % w/w (for Bangladesh)
Absorbance of sample    Â
 Standard Premix taken in g 20.4
= ---------------------------- x ---------------------------------
x --------- x 5
Absorbance of standard Â
 Sample taken in g 100