This document discusses quantitative analysis methods for single component analysis using UV visible spectroscopy. It describes three main methods: the standard absorptivity method, calibration graph method, and single or double point standardization. The standard absorptivity method uses the measured absorbance and a known standard absorptivity value to determine concentration. The calibration graph method plots the absorbances of standard solutions to generate a curve to determine unknown concentrations. Single or double point standardization measures the absorbance of a sample and standard to calculate the sample concentration based on the proportional relationship between absorbance and concentration.

1. QUANTITATIVE ANALYSIS METHODS IN UV VISIBLE SPECTROSCOPY:
SINGLE COMPONENT ANALYSIS METHODS
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PRESENTED BY,
Anjana P Dinesh
M Pharm
College Of Pharmaceutical Sciences,
Government Medical College, Kannur

2. UV VISIBLE SPECTROSCOPY
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Fig 1:UV Spectroscopy

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 Single-component pharmaceutical assays can be determined using single-point standardization, which
involves measuring the absorbance spectrum of a standard solution of the reference sample and a
sample solution.
 The concentration of the absorbing substance is mainly calculated by using 3 methods:
SINGLE-COMPONENT ANALYSIS METHODS
1. Standard absorptivity method
2. Calibration graph
3. Single or double-point standardization

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STANDARD ABSORPTIVITY VALUE
 The concentration of an unknown compound can be determined by using the standard absorptivity
value and the measured absorbance.
 Mainly used for stable substances – broad absorption bands.
 This method is used when the substance is expensive or difficult to obtain.
A =A1%
1 cmbc
A= absorbance of the sample
A1%
1 cm= standard absorptivity
b= path length
C= concentration of a substance

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CALIBRATION GRAPH METHOD
 The absorbances of a number of standard solutions of the reference substance at the concentration
of the sample solutions are measured and a calibration graph is drawn.
0
0.05
0.1
0.15
0.2
0.25
0 100 200 300 400 500 600 700 800 900
ABSORBANCE
CONCENTRATION
CALIBRATION CURVE
Fig 2:Calibration Graph

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SINGLE OR DOUBLE-POINT STANDARDISATION
 This method involves the measurement of the absorbance of a sample solution and of a
standard solution of the reference substance.
 The concentration of a substance in the sample is measured from the proportional relationship
between the absorbance and concentration.
Ctest= Atest x Cstd
Astd
Ctest=concentration of sample
Atest=absorbance of sample
Cstd=concentration of standard
Astd=absorbance of standard

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REFERENCES
1.Practical pharmaceutical chemistry;4th edition-part two;A.H Beckett,J B Stenlake;pg
no:278-281.
2.Principles of instrumental analysis;6th edition ;Holler,Skoog,Grouch;pg no:369-375.
3. https://www.slideshare.net/DivyaV44/uvvisible-spectroscopy.
4. https://www.slideshare.net/suasini/uv-and-visible-appications.
5. wikimedia.org/wiki/File:Schematic_of_UV-_visible_spectrophotometer.png

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Thank you