Page 33 - Instrumental Analysis - Pharm D Clinical- 07-PA403
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UV-visible Spectrophotometry
Identification of Colchicine in the BP
• Test solution: Dissolve 5 mg in 100 mL ethanol (96%). Dilute 5 mL of this
solution to 25 mL with the same solvent.
• Spectral range: 230-400 nm.
• Absorption maxima: 243 nm and 350 nm.
• Absorbance ratio: A243/A350 = 1.7 to 1.9.
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Quantitative Analysis
Single-component analysis
• Prepare the sample solution by dissolving the analyte in a suitable
solvent.
• Measure A of the solution at λmax (where A ranges from 0.3 – 1.0 to
give the best instrumental accuracy).
• Calculate concentration of the analyte from the measured A using
one of the following methods:
1- Using standard absorptivity value
2- Using single-point standardization
3- Using calibration graph
4- Using regression equation
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