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| Archives
- 2000 Issues |
| These issues of the Reporter published in 2000 are available
as Adobe Acrobat files. To download or print the file, click on the icon
beside the title. To download Acrobat reader, click on the link at the bottom
of the page. |
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| LIQUID
CHROMATOGRAPHY |
18.12
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Pharmaceutical Applications using Discovery. DSC-18 SPE-96 Well Plates |
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Sample preparation for chromatographic analysis can be time-consuming
and labor intensive. Reporter 18.12 is exclusively devoted to sample
preparation using Solid Phase Extraction (SPE) techniques. Our recently
introduced 96 well plates are highlighted in our lead article where
we present recovery data for a number of pharmaceutical compounds
extracted from spiked serum. The New Products section of this Reporter
lists all the new 96 well plate product offerings as well as accessories.
Under the New Applications section, we discuss the classic alternative
to 96 well plates -the solid phase extraction tube. In this application
we look at sample recoveries of four Sulfa drugs from spiked serum
using an automated workstation to accomplish the extractions. Our
LC Performance Tip gives practical tips on conditioning and equilibrating
96 well SPE plates including the answer to the question of what happens
to recovery if you dry out the well. Finally, our Case Study shows
that by using silica based adsorbents, cleaner chromatograms can be
obtained while obtaining good recoveries of the sample of interest.
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| GAS
CHROMATOGRAPHY |
18.11 |
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| Maximize Column Lifetime Using Supelco Carrier Gas Purifiers |
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Contamination exists in all GC carrier gas. The life of the column
can depend on the levels present. This Reporter discusses the three
main sources of carrier gas contamination. It examines how to eliminate
it, and recommends hydrocarbon, oxygen, and moisture purification
products. In every instance, users should equip their GCs with carrier
gas purification. In this issue, a case stdy relates a scenario where
carrier gas contamination creates a GC problem. The Reporter also
discusses new and innovative GC products, applications, seminars,
and literature now available from Supelco. |
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| LIQUID
CHROMATOGRAPHY |
18.10
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Scale-Up of Fast Analytical to Fast Preparative Separations |
| You've
finally developed that difficult HPLC method and now it's time to
scale up to obtain a gram or larger quantities of the pure material.
Are you going to have to start the method development all over again
when you switch to the prep column? That isn't necessary! Read our
lead article on how to turn fast analytical to fast preparative separations
with a minimum of fuss. Then check out the Case Study on how to keep
large preparative detection peaks on scale. It's a simple procedure
if you have a variable wavelength detector. Our Products section focuses
on how to chose the right preparative column and injector for preparative
separations. If you prefer, you can also find a wealth of method development
information on our web site, as discussed in this issue's LC Performance
Tip. Another unique service you can read about is in our Literature
article on Custom Resin and Media Processing Services. Supelco works
with you to obtain the resins and media specs you require at a quantity
and price that gives you the competitive edge. |
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| GAS
CHROMATOGRAPHY |
18.9 |
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Proper Column Installation – Success on the First Try! |
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first glance, installing a capillary column seems simple. But many
things can go wrong when installing a column, even for the experienced
analyst. If GC operators do not follow a specific process, chromatography
suffers. This issue of the Reporter discusses a robust process for
installing capillary columns. This process includes cutting the column,
preparing the injector, and taking precautions to select and use the
correct components for connecting the column and rebuilding the injector.
In addition to installation, a real-life case stdy is described where
a number of small installation problems add up to big chromatography
problems. The Reporter also discusses new and innovative GC products,
applications, posters, and updated literature now available from Supelco. |
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| LIQUID
CHROMATOGRAPHY |
18.8
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Difficult Separations: Separation of Critical Pairs of Nifedipine
Degradation Products |
| Separation
of critical pairs of compounds in a mixture is of major concern to
analytical chemists under time constraint to develop methods. This
issue begins with a documented approach to a "real-life" separation
of accelerated degradation products of Nifedipine. The steps taken
were designed to obtain a quality separation in the shortest time
frame possible, by using a strategy of automated column switching
employing HPLC phases of complementary selectivity. Optimum methods
were quickly developed for these structurally similar degradants,
including a method for LC/MS analysis. Similarly, the discovery of
a new method for the separation of the difficult pair, vitamin D2
and vitamin D3, is reported. A Case Study demonstrates
the importance of using the correct sample solvent for HPLC analysis,
and the Performance Tip describes the cause of probably the most often
encountered HPLC performance problem. |
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| GAS
CHROMATOGRAPHY |
18.7 |
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The Importance of Pure Air for Maximum FID Performance |
| Analysts
sometimes encounter unstable FID baseline and often attribute it to
column bleed or sample contamination. In many FID separations, unstable
baseline is not column or sample related. Hydrocarbon removal devices
typically scrub hydrocarbons from the air feeding the FID. However,
only certain purification devices completely remove methane that is
often present. This issue's Main Article examines methane contamination
and how to remove it from the air supplying your FID. A case study
is included that illustrates what can happen when FID air purification
devices are not working properly. Also included are new andinnovative
GC products, applications, posters, and updated literature available
from Supelco. |
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| LIQUID
CHROMATOGRAPHY |
18.6 |
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Fast Gradients for RP-HPLC |
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The topic for this issue is fast gradients in reversed-phase HPLC.
The Main article illustrates the transfer of a gradient method from
a standard 15 cm column to a short column (5 cm) while taking advantage
of the higher flow rates the latter affords. Run time is reduced by
a factor of 12. The significance of instrument dwell volume in gradient
method transfer from standard ID columns to narrowbore columns is
discussed in the Case Study, while the Performance Tip concerns itself
with minimizing post-column extra-column volume at the detector flow
cell, an issue most pertinent to applications with narrowbore columns.
The New Products features low volume mixers (2 to 2505L) to enable
direct control of dwell volume for high-pressure mixing systems. New
Applications demonstrate use of fast gradients with drug compounds
and proteins. |
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| GAS
CHROMATOGRAPHY |
18.5 |
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When the Separation Doesn't Work on the First Try... |
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developing a new GC application, it is not unusual to see the first
separation fail. When this happens, experienced GC users draw on their
background to improve the separation. Without this experience, new
GC users often have questions about how to make improvements. This
issue examines an approach to improving a first separation. This process
begins with method conditions, then looks at column dimension changes,
and finally recommends changing the selectivity of the column phase.
A Case Study is included describing a classic story of working with
the wrong column phase as are new and innovative GC components, seminar
transcripts, and applications available from Supelco. |
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| SOLID
PHASE MICROEXTRACTION |
18.4
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SPME Resolves Difficult Matrix Problems |
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issue of the Reporter addresses how SPME resolves Difficult Matrix
Problems. The main article looks at the SPME extraction of complex
matrices. Flavors compounds were identified in an orange juice matrix
below the FID response levels, yet verifiable by GC-Olfactometry.
A second application describes the SPME extraction of volatile sulfur
compounds from saliva and breath (malodors). In both examples, SPME
was able to overcome the complexity of the sample matrix by sampling
the headspace above the sample. We take SPME ON THE ROAD to help you
decide which fiber type is best for your application. In our Performance
Tip, SPME Fiber selection is discussed for the extraction of volatiles.
The Carboxen/polydimethylsiloxane coated SPME fiber was found to be
superior in performance for most volatiles investigateds. A case study
of the use of SPME describes the determination of oxidative byproducts
from milk due to exposure to light and heat. The presence of aldehydes
and dimethyldisulfide in the headspace of the milk product was a strong
indicator of off-taste of the milk product. |
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| LIQUID
CHROMATOGRAPHY |
18.3
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Optimizing HPLC Separations: Samples with Widely Differing Polarities
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| When
confronted with a sample containing widely varying polarities, the
LC chromatographer will typically rely on gradient elution. However,
if gradient elution is not an option, isocratic elution is generally
quite time consuming, and for late eluting peaks, issues of sensitivity
may arise. We address this with an example of ten water-soluble vitamins
[thiamine (B1), riboflavin (B2), pyridoxine (B6), pantothenic acid
(B5), cyanocobalamin (B12), biotin, niacin, niacinamide, folic acid,
and ascorbic acid (C)] which are eluted isocratically in a two step
process. |
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| GAS
CHROMATOGRAPHY |
18.2 |
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Getting Started in Capillary Gas Chromatography |
| Method
development in capillary gas chromatography (GC) may be a daunting
task to new chromatographers. Many choices are possible for columns,
stationary phases, equipment and method conditions. The simplest approach
to getting started includes consulting fellow chromatographers, searching
the literature for existing applications or calling Supelco's Technical
Service department for advice. If these steps are unsuccessful, what
do you do next? |
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| LIQUID
CHROMATOGRAPHY |
18.1
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New Paradigm for HPLC Method Development |
| Reverse-phase
high performance liquid chromatography (RP-HPLC) remains the preferred
analytical tool for pharmaceuticals (1-5). This is true for all stages
of drug development: from high-throughput screening, purification
of final product, to metabolite studies. Method development must then
address the gamut of these applications, whether designed for rapid
generic analysis of combinatorial libraries or highly optimized for
the particular sample set. As such, method development is a vital
part of the entire drug discovery process. |
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