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The ACCTA Library
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| Type | Title | Details |
| Discussion Topics (html and doc) | HPLC
Method Development Tips and Tricks #1: Neutral Compounds |
Read a summary from our recent publication. This document gives a brief overview, along with general suggestions, for getting started with LC method development for neutral compounds. |
| HPLC
Method Development Tips and Tricks #2: Acidic Compounds |
Read our suggestions for separating acidic compounds, taken from our recent publication. | |
| HPLC
Method Development Tips and Tricks #3: BasicCompounds |
Basic compounds present some unique challenges in method development, but two columns provide good separating options, if you know the rules. | |
| HPLC
Method Development Tips and Tricks #4: Zwitterions |
Zwitterions are especially problematic because of their high water solubility, but you can still get good retention and separation if you know where to start. | |
| HPLC
Method Development Tips and Tricks #5: Changing Column Dimensions in HPLC |
Do you want to use a small bore column to save on solvent, or a high speed column to save on time? This topic gives you the simple rules that you need to know. | |
| Do You Need "UPLC" In Your Laboratory? | ACCTA, Inc. takes a critical look at the numbers, not the marketing! We show an example using three different operating modes: standard HPLC, fast LC, and UPLC. Some simple calculations indicate when you might want to consider either fast LC or UPLC. | |
| Drying/Moisture Determination | This article discusses one of the most common laboratory techniques. Yet, this is still a method that is often performed poorly, resulting in unreliable data. The discussion should provide some hints to help you generate better results. | |
| The Importance of Sample Preparation in Modern Analytical Methods | Most methods require sample preparation, but how important is it? Do we give it the importance that it deserves? Read our thoughts on the subject. | |
| Presentation (pdf) | Lessons Learned in Chromatographic Peak Integration | Integration
errors associated with common peak integration methods (drop, valley,
skim) are summarized. The errors can become quite large (>100%)
in some cases if the wrong method is chosen. General recommendations
are provided to minimize these errors. Minnesota Chromatography Forum, May, 2005 |
| Retention Effects for Cationic Analytes on PFP Stationary Phases in Very Dilute Acid Mobile Phases | This
presentation was our first report about the behavior of certain basic
compounds on PFP. We report some interesting trends for both creatine
and creatinine. Minnesota Chromatography Forum, May, 2007 |
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| HPLC Retention Effects for Cationic Analytes on PFP Stationary Phases in Dilute Acid Mobile Phases | This
second report extended our study of retention patterns to other analytes.
Cations showed normal phase behavior as a function of acetonitrile
content, while a hydrophobic marker and other neutral probes exhibited
conventional reversed phase behavior under identical conditions. Increasing
the acid concentration reduced retention of cations, suggesting the
presence of a complementary ion exchange-type mechanism that may not
be due to underlying silica. Pittsburgh Conference, March, 2008 |
|
| Comparison of HILIC and Reversed Phase Ultra-Fast LC Particles For Separating Very Polar Compounds | The
purpose of this work was to compare the use of aqueous normal phase
(ANP), or HILIC, conditions with classic C18 reversed phase conditions
for separation of water-soluble polar compounds, to show the differences
in selectivity that occur across three common stationary phases. A
further objective was to determine if the high efficiency advantages
shown for reversed phase ultra-fast solid core LC particles could
also be realized in an ANP/HILIC separation mode. Pittsburgh Conference, March, 2009 |
|
| Tuning Selectivity to Improve Separations on PFPP Stationary Phases | Tuning
selectivity on traditional reversed phase materials is typically limited
to either switching stationary phases or individual mobile phase components.
This presentation will focus on using the known retention patterns
on pentafluorphenylpropyl (PFPP) phases to tune the selectivity of
the separation of basic pharmaceuticals (e.g., creatinine, procainamide,
protriptyline) relative to neutral, hydrophobic compounds (e.g., phthalates).
Selectivity is changed without a change in the actual mobile phase
components. Pittsburgh Conference, March, 2009 |
|
| Lessons Learned in the Validation of USP <467> –Residual Solvents in Pharmaceuticals | We
reported the results from a validation of the new USP procedure for
residual solvents. Some specific procedural changes were necessary
to produce acceptable results. Minnesota Chromatography Forum, May, 2009 |
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| Development of a Normal Phase HPLC Method for the Separation of Creatinine and Purine Metabolites | A
novel HPLC method was developed that separates and quantifies purine
metabolites on an aminopropyl phase without the use of ion pairing
additives. A single column, multi-wavelength method was shown for
the following analytes: creatinine, xanthine, allantoin, and uric
acid. This method is currently being used for routine urine analysis. Eastern Analytical Symposium, November, 2009 |
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| Preferred Columns and Conditions for Achieving Quantitative HPLC Performance in the HILIC Separation Mode | This
presentation offered advice on obtaining quantitative results under
HILIC operating conditions. Experiments measured equilibration volume,
injection solvent, injection volume, and linearity. Quantitative results
are possible if appropriate precautions are observed. Pittsburgh Conference, March, 2010 |
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