pharmaceutical
Applications
note
RestekCorporation • (800)356-1688 • (814)353-1300 •
#59511A
Improved HPLC Analysis of Analgesics
Analgesics are the largest selling class of pharmaceuticals.
Many people use analgesics in prescription form or in simple
over-the-counter remedies. Headaches, inflammation, colds,
flu, congestion, fever, sneezing, coughing, and muscle aches
are among the list of symptoms that can be treated with
analgesics.
Symptoms, however, often arrive in multiples. For multiple
symptoms, analgesics combined with pain relief, fever
reduction, and other beneficial compounds have been
created. Many of these compounds can be analyzed simulta-
neously using high performance liquid chromatography
(HPLC), thereby improving laboratory efficiency and
productivity. With the selection of the proper LC column
phase, separation becomes a simpler and more manageable
task that does not rely upon extensive preparation proce-
dures or use of ion pairing agents, which often are described
in pharmaceutical compendiums.
Popular compounds for multi-active analgesics include
aspirin, salicylic acid, salicylamide, acetaminophen,
ibuprofen, naproxen, guaifenesin, codeine, oxycodone,
hydrocodone, and caffeine. The Restek Ultra Phenyl,
Allure
™
Acidix, and Allure
™
Basix HPLC column phases
separate mixtures of these pharmaceuticals in a productive
and cost effective manner. The selective chemistry of these
phases provide powerful separation mechanisms.
The interaction of codeine with active residual silanol sites
on improperly deactivated column phases can cause extreme
tailing for this compound. A properly end-capped and base-
deactivated phenyl phase, such as the Ultra Phenyl phase,
can significantly reduce tailing of the codeine peak. In
Figure 1, the Ultra Phenyl column provides excellent peak
shape and superior resolution of guaifenesin and codeine
with a run time of less than six minutes. Furthermore, the
method is MS-compatible because no mobile phase addi-
tives or ion pairing reagents are needed to reduce tailing.
Acidic silanols also can cause undesirable interaction with
analytes containing basic functional groups such as amines
and amides. The fully end-capped Allure
™
Basix column was
developed with specialized functional groups that provide
the desired interaction with nitrogen-based functional
groups such as amines and amides.
Figure1
Excellent peak shape and superior resolution of guaifenesin and codeine using Ultra Phenyl column.
Peak List:
1. codeine
2. guaifenesin
Sample:
Inj.:
5µL
Conc.:
codeine 825µg/mL
guaifenesin 375µg/mL
Solvent:
methanol:water
(50:50)
Column:
Ultra Phenyl
Catalog #:
9105565
Dimensions:
150 x 4.6mm
Particle Size:
5µm
Pore Size:
100Å
Conditions:
Mobile Phase:
10mM ammonium
formate, pH 2.5:
acetonitrile
(80:20,v/v)
Flow:
1.2mL/min.
Temp.:
25°C
Det.:
UV @ 280nm
1
2
0
1 2 3 4
5
6 min.
