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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:
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 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
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
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
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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