Rapid and Sensitive Spectrophotometric ... - AstonJournals

4 Research Article
2.2 Materials
Pharmaceutical grade propranolol hydrochloride (PPH) was received from Cipla India Ltd., Mumbai, India, as a gift
and used as received. The following formulations were obtained from commercial sources and subjected to
analysis: Monoprolol-20 (Cosmo Life Sciences Ltd., India), Ciplar – 40 (Cipla Ltd., India) and Betacap-40 from (Sun
Pharma Ltd., India).
2.3 Reagents and chemicals
All the reagents and solvents used were of analytical-reagent grade. Bromothymol blue (BTB), bromocresol green
(BCG) and bromocresol purple (BCP) (all from Loba Chemie Ltd., Mumbai, India) solutions were prepared daily as
0.1% BTB and BCP and 0.05% BCG in dichloromethane.
2.4 Standard stock solution of PPL
Pure propranolol hydrochloride (11.4 mg) was dissolved in 20 ml water in a 125 ml separating funnel, 5 ml of liquid
ammonia was added followed by 20 ml of dichloromethane. The content was shaken for 15 minutes. The lower
organic layer was collected in a beaker containing anhydrous sodium sulphate. The water-free organic layer was
transferred into a 100 ml calibrated flask and diluted to the volume with the same solvent to get 100 µg ml -1 with
respect to PPL (hydrochloride free propranolol). This solution was diluted appropriately with dichloromethane to
get working concentrations of 10 µg ml -1 in both the methods A and B, and 12 µg ml -1 for use in method C,
respectively.
2.5 Recommended Procedures
2.5.1 BTP method (method A)
Different aliquots (0.2, 0.5, 1.0, 2.0, 3.0 and 3.5 ml) of a standard PPL (10 µg ml -1 ) solution were transferred into a
series of 5 ml calibrated flasks using a micro burette and to each flask was added 1 ml of 0.1% BTB solution. The
mixture was diluted to the volume with dichloromethane and mixed well. The absorbance of resulting yellow
colored solution was measured at 420 nm against a reagent blank.
2.5.2 BCG method (method B)
Varying aliquots (0.2, 0.5, 1.0, 2.0, 3.0 and 3.5 ml) of a standard PPL (10 µg ml -1 ) solution were transferred into a
series of 5 ml calibrated flasks using a micro burette and to each flask was added 1 ml of 0.05% BCG solution. The
mixture was diluted to the volume with dichloromethane and mixed well. The absorbance of resulting yellow
colored solution was measured at 425 nm against a reagent blank.
2.5.3 BCP method (method C)
Into a series of 5 ml calibration flasks, aliquots (0.25, 0.5, 1.0, 2.0, 3.0 and 3.5 ml) of standard PPL solution (12 µg
ml -1 ) equivalent to 0.6 – 8.4 µg ml -1 PPL were accurately transferred and the total volume in each flask was brought
to 3.5 ml by adding dichloromethane. To each flask 1 ml of 0.1 % BCP solution in dichloromethane was added and
mixed well. The absorbance of the yellow colored ion-pair complex was measured at 420 nm against the reagent
blank.
2.5.4 Procedure for dosage forms
Ten tablets or content of ten capsules were weighed accurately and ground into fine powder. An amount of the
powder equivalent to 11.4 mg of PPH was weighed into a 125 ml separating funnel. The extraction procedure used
for pure drug was followed for tablet/capsule powder. The resulting solution was diluted to get working
concentration (10 and 12 µg ml -1 PPL) and suitable aliquots were analyzed following the procedures described
above.
2.5.5 Procedures for selectivity study
A placebo blank of the composition: talc (100 mg), starch (50 mg), acacia (50 mg), methyl cellulose (100 mg),
sodium citrate (50 mg), magnesium stearate (100 mg), and sodium alginate (50 mg) was prepared and 20 mg was
extracted with dichloromethane and solutions were made as described under preparation of dosage forms. A
convenient aliquot of solution was subjected to analysis following the recommended procedures.
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