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Chromatography Integration and Trouble-shooting. Presented by: Marlene Moore [email protected] October 2007. Agenda. Problems Tools Solutions. Problems. Baseline Disturbances Irregular Peak Shapes, Sizes Retention Time Shifts

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Chromatography integration and trouble shooting l.jpg

Chromatography Integration and Trouble-shooting

Presented by: Marlene Moore [email protected]

October 2007

Agenda l.jpg

  • Problems

  • Tools

  • Solutions

Problems l.jpg

  • Baseline Disturbances

  • Irregular Peak Shapes, Sizes

  • Retention Time Shifts

  • Loss of Separation or Resolution

  • Quantitation Difficulties

  • Rapid Column Deterioration

  • Ghost Peaks

  • Broad Solvent Front

Baseline disturbances l.jpg
Baseline Disturbances






Spiking l.jpg

  • Particulate Matter Passing Through Detector

  • Loose Connections

    • Cables

    • Circuit boards

Noise l.jpg

  • Contaminated Injector/column

  • Physical Defect Detector

  • Defective Detector Board

  • Carrier Gas Leak at Septum or Column


    • Column in Flame

    • Incorrect Combustion Gases or Flow Rate/leak

  • ECD, TCD

    • Air Leak

Wander l.jpg

  • Contaminated Carrier Gas

    • Isothermal Conditions

  • Contaminated Gas Chromatograph

  • Poor Control of Carrier Gas or Detector Gas Flows

  • Poor Thermal Control of Detector

Drift l.jpg

  • Septum Bleed

  • Upward

    • GC or column contamination

    • Damaged stationary phase

  • Downward

    • Incomplete conditioning of column

    • Unequilibrated detector

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  • Contamination:

    • Injector, column, detector

    • Carrier gas - change/install impurity traps

  • Column Inserted Into Flame (FID, NPD, FPD)

  • Malfunctioning or Improperly Set Recording Device

Peak shape l.jpg
Peak Shape

Peak Shape tells the story of your chromatography

Irregular peak shapes l.jpg
Irregular Peak Shapes







No peaks l.jpg
No Peaks

  • Plugged Syringe

  • Broken Column

  • Injecting Sample Into Wrong Injector

  • Column Installed in Wrong Detector

  • Integrator Reading Wrong Signal or Not Connected

  • Detector Not on

  • Temperature

    • Oven not heated

    • Column temperature too low

    • Injection port temperature too low

  • Detector Gases Improperly Set or Not on

  • Very Low or No Carrier Gas Flow

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Reduced Peaks

  • Plugged Syringe

  • Change in Injection Technique

  • Large Leak - Injector

  • Split Ratio Too High

  • Too Short of Purge Activation Time for Splitless Injections

  • Very High Septum Purge Flow

  • Too Low Injector Temperature

  • Column Temperature Too Low

  • Sample Components Absorbed by Column or Inlet Liner

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Reduced Peaks

  • Initial Temperature Column Too High for Splitless or On-column Injections

  • High Background Signal -

    • Contamination

    • Excessive column bleed

    • Check auto zero function and setting

  • Improperly Operated Detectors

  • Impurities Carrier Gas or Detector Gas

  • Detector Compound Mismatch

  • Excessive Attenuated Integrator Signal

  • Sample Concentration or Integrity Problems

Tailing peaks l.jpg
Tailing Peaks

  • Active Injector Liner or Column

  • Contaminated

    • Injector liner

    • Column

  • Dead Volume Caused by Poorly Installed Liner, Column or Union

  • Poorly Cut Column End

  • Polarity Mismatch - Stationary Phase, Solute or Solvent

  • Cold Spot in the Flow Path

Tailing peaks17 l.jpg
Tailing Peaks

  • Solid Debris in Liner or Column

  • Poor Injection Technique - Too Slow

  • Too Low of a Split Ratio

  • Overloading on a PLOT Column

    • Decrease sample amount

    • Amines and carboxylic acids tail on most columns

    • Need ph modified stationary phase

  • Some Peaks Always Exhibit Tailing

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Rounded or Flat Topped Peaks

  • Overloaded Detector

  • Exceeding Range of Integrator

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Split Peaks

  • Detector Overloaded

  • Poor Injection Technique

  • Poorly Installed Column Into Injector

  • Column Temperature Fluctuations

  • Coelution of Two or More Compounds

  • Mixed Sample Solvent for Splitless or On-column Injections.

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Negative Peaks

  • All Peaks Negative - Polarity Check Connectors

  • TCD - Select Peaks

    • Thermal conductivity of compound greater than carrier gas

  • ECD - After Positive Peak

    • Dirty or old ECD cell

Retention time shifts l.jpg
Retention Time Shifts

  • Different Column Temperature

  • Different Carrier Gas Flow or Linear Velocity

  • Leak in Injector - Septum

  • Contaminated Column

  • Change in Sample Solvent

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Loss of Separation/Resolution

  • Contaminated Column

  • Damaged Stationary Phase

  • Different Column Temperature, Carrier Flow Rate, Column

  • Large Changes in Sample Concentrations

  • Improper Injector Operation

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Quantitation Difficulties

  • Injection Techniques

  • Split Discrimination

  • Different Purge Activation Time for Splitless Injection

  • Baseline Disturbances

  • Improper Integrator Settings

  • Inconsistent Detector Gas Flows or Temperatures

  • Column or Liner Activity

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Rapid Column Deterioration

  • Exposure of Column to Air at Elevated Temperatures

  • Exceeding Upper Temperature Limit of Column

  • Chemical Damage

  • Contamination of Column With High Molecular Weight Materials

  • Column Breakage

Ghost peaks l.jpg
Ghost Peaks

  • Contamination

    • Injector

    • Column

  • Septum Bleed

  • Dirty Syringe

  • Sample Too Large

  • Previous Run Terminated Too Soon


Broad solvent front l.jpg
Broad Solvent Front

  • Poorly Installed Column

  • Leak in the Injector

  • Solvent Interacting with Detector

  • Too Low

    • Split Ratio (Flow)

    • Injector Temperature

  • Too Long Purge Activation for Splitless Injections

  • Large Injection Volume

  • Low Column Temperature and High Boiling Solvent

  • High Column Temperature and Low Boiling Solvent

Tools l.jpg

  • Flowmeter

  • Syringe (NEW)

  • Methane or Nonretained Compound

  • Septa, Ferrules, Injection Liners (NEW)

  • Leak Detector

  • Column Test Mixture (Reference)

  • Checkout Column

  • Instrument Manuals

Solutions l.jpg

Quickest Solution ----

Improve Chromatography ---

Do Manual Integration ---

Get Results out Fast !!



Solutions30 l.jpg

  • Preventive Maintenance

    • Clean detector

    • Clean injector

    • Clean and repair parts

    • Clean and tighten connections

    • Follow instrument manual suggestions

  • Allow Time for Optimizing System

    • Integration parameters

    • Programs

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Does anyone have a question?

Question !

Where do you document your trouble shooting?