A UT Arlington chemistry
professor, renowned for his work in the area of chemical separations, is
leading an effort to find a more accurate way to measure water content in
pharmaceuticals – a major quality issue for drug manufacturers.
Daniel W. Armstrong, UT
Arlington’s Robert A. Welch Chair in Chemistry, says the new technique could be
100 times more sensitive than one of the most popular current methods.
“The analysis for water in many consumer products, including drugs, is
one of the most required tests done in the world,” said Armstrong. “Current
methods have many shortcomings, including poor sensitivity and reproducibility;
they cannot be used for all products and they can be time consuming. I
believe our new ‘ionic liquid’ method offers improvements in all these areas.”
Armstrong and two graduate
students recently wrote about their new research in a paper that will be in
the June issue of the Journal of
Pharmaceutical and Biomedical Analysis. The publication describes using
headspace gas chromatography and an ionic liquid gas chromatography column Armstrong’s
lab developed to measure moisture content in active pharmaceutical ingredients
such as ibuprofen, tetracycline and ephedrine. Water content can affect the
stability and shelf life of a drug and, when it is too high, cause microbial
growth, according to the paper.
Chromatography is the process of
separating a chemical mixture to measure its components. Headspace gas
chromatography, or HSGC, involves the measuring of volatile analytes, or
chemical components, as they diffuse into a “headspace” at the top of a tube of
sample, including solids. The new method combines HSGC with the use of ionic
liquids. Ionic liquids consist of a mixture of positively and negatively
charged molecules. They have a variety of advantages as solvents.
Currently, two methods are most
commonly used to measure moisture content. One is called weight loss on drying,
or LOD; the other is called Karl Fischer Titration, or KFT. The newly described
work from Armstrong’s lab is useful on more types of drug ingredients than LOD
and is more than 100 times more sensitive in some cases than KFT. It also can
be used for much smaller samples and be automated, the paper said.
Graduate student Lillian A.
Frink is lead author on the paper and Choyce A. Weatherly, also a graduate
student in Armstong’s lab, is a co-author.
“We think industry will utilize
this method based on its broad applicability, its high accuracy, and the sample
size requirements,” said Frink. “It also doesn’t have side-reactions like
current methods, which make them inaccurate."
Armstrong has been a leader in
the characterizing and synthesizing ionic liquids. He also holds patents on
several open tubular capillary gas chromatography columns that utilize ionic
liquids, including those used in the current research.
The newly published paper is called “Water determination in active
pharmaceutical ingredients using ionic liquid headspace gas chromatography and
two different detection protocols.” It is available here: http://www.ncbi.nlm.nih.gov/pubmed/24561336.
Armstrong joined UT Arlington in 2006 and is
the author of more than 550 scientific publications, including 29 book
chapters, and holds 23 U.S. and international patents.
His lab recently made headlines when they
debuted research on a new method for testing for performance enhancing drugs.
That research, which was presented at the 247th National Meeting
& Exposition of the American Chemical Society, showed that their protocol
could be up to 1,000 more sensitive than many current tests. More information
is available here: http://www.uta.edu/news/releases/2014/03/armstrong-sportsresearch.php.
About UT Arlington
University of Texas at Arlington is a comprehensive research institution and
the second largest institution in The University of Texas System. The Chronicle of Higher Education ranked
UT Arlington as the seventh fastest-growing public research university in 2013.
U.S. News & World Report ranks UT Arlington fifth in the nation for
undergraduate diversity. Visit www.uta.edu to learn more and