Pitfalls and Errors for HPLC in Pictures presents accurate, focused information that tells busy chefs what to do and how to do it.

Features:

• Offers almost 100 exemplary solutions for problems
• Examples are presented with a concise, instructive text and an informative figure
• Includes essential fundamentals as well as helpful strategies such as equipment tests or quality assurance strategies
• Practice-oriented guide for obtaining correct and reliable analytical results

Contents

Fundamentals

• Chromatography.
• Chromatographic Figures of Merit.
• The Resolution of Two Peaks.
• Reduced Parameters.
• The Van Deemter Curve.
• Peak Capacity and Number of Possible Peaks.
• Statistical Resolution Probability: Simulation.
• Statistical Resolution Probability: Example.
• Precision and Accuracy of an Analytical Result.
• Standard Deviation.
• Uncertainty Propagation.
• Reproducibility in Trace Analysis.
• Ruggedness.
• Calibration Curves.
• The HPLC Instrument.
• The Detector Response Curve.
• Noise.
• Causes and Effects Presented as an Ishikawa Diagram.
• The Possible and the Impossible

Pitfalls and Sources of Error

• Mixing of the Mobile Phase.
• Mobile Phase pH.
• Adjustment of Mobile Phase pH.
• Inadequate Purity of a Mobile Phase Solvent.
• Inadequate Purity of a Mobile Phase Reagent.
• System Peaks and Quantitative Analysis.
• Sample Preparation with Solid Phase Extraction.
• Poor Choice of Sample Solvent: Peak Distortion.
• Poor Choice of Sample Solvent: Tailing.
• Sample Solvent and Calibration Curve.
• Impurities in the Sample.
• Formation of a By-Product in the Sample Solution.
• Decomposition by the Sample Vial.
• Artifact Peaks from the Vial Septum.
• Formation of an Associate in the Sample Solution.
• Precision and Accuracy with Loop Injection.
• Injection Technique.
• Injection of Air.
• Sample Adsorption in the Loop.
• Extra-Column Volumes.
• Dwell Volume.
• Elution at t0.
• Classification of C18 Reversed Phases.
• Different Selectivity of C18 Reversed Phases.
• Different Batches of Stationary Phase.
• Chemical Reaction within the Column.
• Recovery and Peak Shape Problems with Proteins.
• Double Peaks from Stable Conformers.
• Influence of Temperature on the Separation.
• Thermal Non-Equilibrium within the Column.
• Influence of the Volume Flow Rate on the Separation.
• Influence of Run Time and Volume Flow Rate on Gradient Separations.
• UV Spectra and Quantitative Analysis.
• UV Detection Wavelength.
• Fluorescence Quenching by Air.
• Detector Overload.
• Influence of the Retention Factor on Peak Height.
• Influence of the Volume Flow Rate on Peak Area.
• Leaks in the HPLC Instrument.
• Impairment of Precision as a Result of Noise.
• Determination of Peak Area and Height at High Noise.
• Peak Height Ratios.
• Incompletely Resolved Peaks.
• Area Rules for Incompletely Resolved Peaks.
• Areas for a 1 : 10 Peak Pair.
• Heights for a 1 : 10 Peak Pair.
• Quantitative Analysis of a Small Peak.
• Incompletely Resolved Peaks with Tailing.
• Integration Threshold and Number of Detected Peaks.
• Detector Time Constant and Peak Shape.
• Quantitative Analysis in the 99 % Range.
• Correlation Coefficient of Calibration Curves

Useful Strategies

• Column Tests.
• Apparatus Tests.
• Wavelength Accuracy of the UV Detector.
• Internal Standards.
• A Linearity Test.
• Rules for Accurate Quantitative Peak Size Determination.
• High-Low Chromatography.
• Control Charts.
• Verification of the Analytical Result by Use of a Second Method.
• Description of Ruggedness.
• Rules for Passing On an HPLC Method.
• Quality Assurance in the Laboratory.
• Standard Operating Procedures.
• Method Validation.
• Some Elements of Validation.
• A Validation Example.
• Measurement Uncertainty.
• Formal Quality Assurance Systems

Index

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