2013-5. Gradient Elution, Part III: Surprises | LCTSBIBLE.COM

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2013-5. Gradient Elution, Part III: Surprises

May 1, 2013

Sometimes when changes are made to gradient conditions, the result isn’t what was expected.

LCGC 31(5) 382-389 (2013)

John W. Dolan

ERRATUM: The last word on p. 388 should be “decrease” not “increase.” A change in particle size from 3 microns to 5 should reduce the pressure, not increase it.

Tags: column dimensions, flow rate, gradient elution, isocratic vs. gradient, k*, particle size

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2012-8. Questions from Afar

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2009-4. Calibration Curves, Part II: What are the Limits?

2009-3. Calibration Curves, Part I: To b or Not to b?

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2008-2. Ion Pairing — Blessing or Curse

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2007-11. The Perfect Method, Part VI: Make It Faster

2007-10. The Perfect Method, Part V: Changing Column Selectivity

2007-9. The Perfect Method, Part IV: Controlling Peak Spacing

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2007-7. The Perfect Method, Part II: Where to Start?

2007-6. The Perfect Method, Part I: What is Your Goal?

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2002-10. The Hazards of Adjusting Gradients

2002-9. Performance Qualification of LC Systems

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2000-1. Starting Out Right, Part II — Measuring Satisfaction

1999-12. Starting Out Right, Part I — Selecting the Tools

1999-11. Reader’s Questions: Carryover, Mobile-Phase Temperature, and Column Care

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1999-7. Priming Injections

1999-6. How Much Is Too Much?

1999-5. LC Troubleshooting On-Line with Chromatography Forum

1999-4. Lessons in Column Washing

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1999-2. Basic Compounds — Starting on the Right Foot

1999-1.UV Detector Noise

1998-12. Column Temperature Effects in Gradient Elution

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1998-10. Autosampler Precision

1998-9. From the Mail Bag — Dirty Loop, Precolumn Use, In-Line Degassing, and Injector Plumbing

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1998-5. Sample Overload — Friend or Foe?

1998-4. Column Packing — What’s at the Bottom of It?

1998-3. Extracolumn Band Broadening from Injection and Peak Transfer

1998-2. Ghost Peaks and Aerated Sample Solvent

1998-1. Scaling Gradients

1997-12. Reproducibility Problems

1997-11. A Valuable Source of Help

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1997-6. Maintaining Autosampler Performance

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1997-4. Air: Poison for Liquid Chromatographs

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1996-6. Readers’ Questions about Mobile-Phase Additives

1996-5. Noise Problems: A Case Study

1996-4. Problems with Gradient Methods

1996-3. Water Problems: A Case Study

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1995-10. Testing Autosampler Performance

1995-9. Internal Standard Problems, Buffer Precipitation, and Column Storage

1995-7. Pump Seal Problems

1995-6. Mobile-Phase Proportioning Problems and Standard Operating Procedures

1995-5. International Liquid Chromatography Problems

1995-4. Odds and Ends from the Mailbox

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1995-2. Problems with Water

1995-1. Reader Questions

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1994-11. Questions about Ion Pairing

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1994-9. Obtaining Separations, Part IV: Putting It All Together

1994-7. Obtaining Separations, Part III: Adjusting Column Conditions

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1994-5. Obtaining Separations, Part I: A Look at Retention

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1993-6. Avoiding the Pitfalls of Published Methods

1993-5. Aggressive Mobile Phases — A Case Study

1993-4. Air Problems

1993-3. Recycling Revisited

1993-2. Amine Adsorption — A Case Study

1993-1. Column Care and Feeding

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1992-9. Buffer Precipitation Problems

1992-7. LC Problem Guide

1992-6. Solvent Recycling

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1992-4. The Case of the Mystery Gradient Peak

1992-3. LC Problems – Past, Present, and Future

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1992-1. Extracolumn Effects

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1991-11. Retention-Time Problems: Answers to Readers’ Questions

1991-10. NISA A Service Alternative

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1991-7. Using Dead Time, Retention, and the Capacity Factor as Diagnostic Tools

1991-6. Changing System Conditions

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1991-4. Pumps: Operation and Maintenance

1991-3. Retention-Time Drift A Case Study

1991-2. Method Reproducibility, Leaks, and Check-Valve Problems

1991-1. Sample Adsorption in Liquid Chromatography Injection Valves

1990-12. Pump Problems

1990-11. Retention-Time Variation: A Case Study

1990-10. Column and Mobile Phase Problems

1990-9. Baseline Noise: A Case Study

1990-7. Ghost Peaks and Column Problems

1990-6. Peak Tracking

1990-5. Column and Detector Problems

1990-4. Problems in Size-Exclusion Chromatography

1990-3. Mobile Phase Buffer Problems

1990-2. Problems with Small-Volume Columns

1990-1. System-to-System Variation

1989-12. Isolating and Correcting LC Problems

1989-11. Preventive Maintenance of Sample-Injection Valves

1989-10. Readers’ Questions

1989-9. Passivation of Liquid Chromatography Components

1989-7. Column Flushing Demystified

1989-6. Peak Tailing

1989-5. Readers’ Questions

1989-4. Peak Problems

1989-3. Troubleshooting Pump Problems

1989-2. Readers’ Questions

1989-1. Mobile Phase Proportioning Problems: A Case Study

1988-12. Method Optimization and Maintenance Using a Resolution Map

1988-11. Recognizing and Eliminating Noise Problems in Liquid Chromatography

1988-10. Troubleshooting LC Fittings, Part II

1988-9. Troubleshooting LC Fittings, Part I

1988-7. Mobile Phase Proportioning Problems

1988-6. Blocked Columns and Tubing

1988-5. Late Peaks and Gradient Reproducibility

1988-4. Rules of Thumb

1988-3. Readers’ Questions

1988-2. Ghost and Vacancy Peaks

1988-1. More on Solvents

1987-12. Shortcuts for LC Measurements

1987-11. Column Stability: A Case Study

1987-10. Mobile Phase Problems

1987-9. Capacity Factor, Plate Number, Extracolumn Effects, and More

1987-7. Readers’ Questions

1987-6. Gradient Elution Separation Problems, Part II

1987-5. Gradient Elution Separation Problems, Part I

1987-4. Potpourri

1987-3. Troubleshooting Autosamplers, Part II

1987-2. Troubleshooting Autosamplers, Part I

1987-1. Maintaining an LC System with Ease

1986-12. Problems Resulting from Normal System Variability

1986-11. Extracolumn Effects: Two Case Studies

1986-10. Readers’ Questions

1986-9. Readers’ Questions

1986-7. LC User Survey: Data-System Problems

1986-6. LC User Survey: Detector Problems

1986-5. LC User Survey: Autosampler Problems

1986-4. Readers’ Questions

1986-3. Separation Artifacts III: Secondary-Retention Effects in Reversed-Phase Chromatography

1986-2. Separation Artifacts II: Extracolumn Effects, Tailing, and Strong Retention Sites

1986-1. Separation Artifacts I: Sample Overload and Injection-Solvent Problems

1985-12. Sample Injection Valves

1985.11 Equipment Usage

1985-10. Troubleshooting

1985-9. Troubleshooting

1985-7. Troubleshooting

1985-6. Troubleshooting

1985-5. Common Column Problems

1985-4. Troubleshooting

1985-3. Troubleshooting

1985-2. Connecting Tubing

1985-1. Peak Shape

1984-11. Autosamplers

1984-10. Chromatographic Theory as a Problem-Isolation Aid: Part II

1984-9. Chromatographic Theory as a Problem-Isolation Aid: Part I

1984-8. Mobile Phase Preparation

1984-7. Service Contracts

1984-6. Optical Detectors Part III: Variable-Wavelength UV Detectors

1984-5. Optical Detectors Part II: Fixed-Wavelength UV Detectors

1984-4. Optical Detectors, Part I: General Principles

1984-3. Piston-Diaphragm Pumps

1984.2 Reciprocating Piston Pumps

1984-1. Chromatographic Fittings: Proper Use to Minimize Dead Volume

1983-8. Problem Isolation: Shortening Troubleshooting Time

1984-7. Recordkeeping: Plan Ahead to Minimize Downtime

1983-3. Troubleshooting: HPLC Sample Preparation and Introduction

1983-2. Troubleshooting the Mobile Phase of Your HPLC System

1983-1. An HPLC Troubleshooting Guide