PRACTICAL : UV Spectroscopy Part 1: Absorption spectrum of sodium aminosalicylate Determine the λmax from the spectrum:

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PRACTICAL
: UV Spectroscopy
Part 1: Absorption spectrum of
sodium aminosalicylate
Determine the λmax from the
spectrum:
1. 243nm
2. 290nm
Concentration = 0.001% , absorbance
= 0.5416
A= A(1%, 1
cm).c.l
Part 2: Beer’s Law, Specific Absorbance
and Molar Absorptivity
Determine the optimal wavelength values for 0.001% sodium
aminosalicylate with readings collected at 2 nm intervals.
Wavelength (nm)
Blank absorbance
Absorbance for 0.001% sodium
aminosalicylate
First reading
Second reading
Average
288
0.0000
0.0263
0.0269
290
0.0000
0.0277
0.0281
292
0.0000
0.0270
0.0268
294
0.0000
0.0258
0.0252
296
0.0000
0.0150
0.0156
Part 3: Standard curve and
samples
(i) Preparation of Standard
curve
λmax set at nm
Stock solution: 0.0010% w/v sodium aminosalicylate
Concentration
%w/v
Final volume,
mL
Volume of
0.0010%
amino salicylate,
mL
Absorbance
reading 1
Absorbance reading 2
Average
0.0002
50.0
0.1054
0.1056
0.0004
50.0
0.2216
0.2218
0.0006
50.0
0.3331
0.3331
0.0008
50.0
0.4423
0.4425
0.0010
50.0
0.5415
0.5417
Unknown 1
-
-
0.8667
0.8667
Unknown 2
-
-
0.5325
0.5325
Part 4: Determination of Concentrations
(i) Calibration graph method
The concentration of ‘Unknown 1’ =
(ii) Absolute method
The concentration of ‘Unknown 2’ =
(iii) Comparative method
The concentration of ‘Unknown 2’ =
Discuss the results obtained from absolute method and
comparative method in determination of concentration of Unknown
2.