Application
Note: 51854
Analysis of Acetaminophen with the
Evolution Array UV-Visible Spectrophotometer
Nicole Kreuziger Keppy, Gordon Bain, Ph.D., Michael W. Allen, Ph.D., Thermo Fisher Scientific, Madison, WI, USA
Introduction
Key Words
• Equation Calculator
A UV-Visible spectrophotometer is an essential tool for any
quality control laboratory. It is useful for identity, purity
and quantitative analysis assays of raw materials, active
ingredients and final products in the manufacturing of:
• Paracetamol
• Pharmaceuticals
• Percent Assay
• Cosmetics
• Acetaminophen
• UV-Visible
Spectroscopy
• United States
Pharmacopeia
(USP)
• Food and beverages
• Specialty chemicals
The wavelength and peaks/valleys functions in the
wavelength monitoring mode of the Thermo Scientific
VISIONcollect software allow the user to identify sample
components. Absorbance and ratio functions provide
confirmation of the purity and quantity of these components.
In this application note, the quantity and percent assay of
acetaminophen (also known as Paracetamol) is determined
with a Thermo Scientific Evolution Array UV-Visible
spectrophotometer according to USP methods.
Figure 1: Chemical structure of acetaminophen, C8H9NO2
Experimental
A concentrated stock solution of acetaminophen was
prepared by dissolving approximately 20 mg of dried
acetaminophen standard in 2 mL of methyl alcohol.
This solution was brought to a total volume of 100 mL
with water. A working standard solution was prepared
by removing 3 mL of the stock solution and bringing this
solution to a total volume of 100 mL with water. A test
sample of acetaminophen was prepared in the same
fashion as the standard. Water was used as the blank.
The absorbance of the working standard and test
sample was measured at 244 nm using the parameters
indicated in Figure 2. The full-spectrum result for
acetaminophen is shown in Figure 3.
Figure 2: Experimental Parameters
Conclusion
In addition to these
Assays for pharmaceuticals can easily be performed using
the Evolution™ Array™ UV-Visible spectrophotometer and
VISIONcollect™ software. According to the USP 29 assay
for acetaminophen, the test sample must contain “not less
than 98.0 percent and not more than 101.0 percent of
C8H9NO2, calculated on the anhydrous basis.”1 In this
experiment, the percent assay of acetaminophen in the
test sample was determined experimentally to be 98.5%.
Thus, this acetaminophen test sample was found to be in
agreement with the USP assay test for acetaminophen.
offices, Thermo Fisher
References
Figure 3: Spectra of acetaminophen standard and test sample
1. United States Pharmacopeia and National Formulary (USP 29 NF 24).
Supplement No. 2. Rockville, MD: United States Pharmacopeia
Convention; 2006: 3711.
The values for the quantity and percent assay of
acetaminophen were calculated using the following
equations.
Quantity of acetaminophen in the test sample:
= standard sample weight (mg) X
= 20.1 mg X
0.0549
A244 (test sample)
A244 (standard)
0.0558
= 19.8 mg
Percent assay of acetaminophen in the test sample:
= 100 X
= 100 X
Calculated Qty in test sample
Weight of test sample
19.8
20.0
= 98.5%
The quantity of acetaminophen in the test sample was
experimentally determined to be 19.8 mg. The percent
assay was determined to be 98.5%.
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