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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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Presentation Transcript
agenda
Agenda
  • Problems
  • Tools
  • Solutions
problems
Problems
  • 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
Baseline Disturbances

spiking

noise

wander

drift

offset

spiking
Spiking
  • Particulate Matter Passing Through Detector
  • Loose Connections
    • Cables
    • Circuit boards
noise
Noise
  • Contaminated Injector/column
  • Physical Defect Detector
  • Defective Detector Board
  • Carrier Gas Leak at Septum or Column
  • FID, NPD, FPD
    • Column in Flame
    • Incorrect Combustion Gases or Flow Rate/leak
  • ECD, TCD
    • Air Leak
wander
Wander
  • Contaminated Carrier Gas
    • Isothermal Conditions
  • Contaminated Gas Chromatograph
  • Poor Control of Carrier Gas or Detector Gas Flows
  • Poor Thermal Control of Detector
drift
Drift
  • Septum Bleed
  • Upward
    • GC or column contamination
    • Damaged stationary phase
  • Downward
    • Incomplete conditioning of column
    • Unequilibrated detector
offset
Offset
  • 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
Peak Shape

Peak Shape tells the story of your chromatography

irregular peak shapes
Irregular Peak Shapes

tailing

fronting

split

reduced

rounded

negative

no peaks
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
reduced peaks
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
reduced peaks15
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
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
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
rounded or flat topped peaks
Rounded or Flat Topped Peaks
  • Overloaded Detector
  • Exceeding Range of Integrator
split peaks
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.
negative peaks
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
Retention Time Shifts
  • Different Column Temperature
  • Different Carrier Gas Flow or Linear Velocity
  • Leak in Injector - Septum
  • Contaminated Column
  • Change in Sample Solvent
loss of separation resolution
Loss of Separation/Resolution
  • Contaminated Column
  • Damaged Stationary Phase
  • Different Column Temperature, Carrier Flow Rate, Column
  • Large Changes in Sample Concentrations
  • Improper Injector Operation
quantitation difficulties
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
rapid column deterioration
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
Ghost Peaks
  • Contamination
    • Injector
    • Column
  • Septum Bleed
  • Dirty Syringe
  • Sample Too Large
  • Previous Run Terminated Too Soon

BOO!

broad solvent front
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
Tools
  • Flowmeter
  • Syringe (NEW)
  • Methane or Nonretained Compound
  • Septa, Ferrules, Injection Liners (NEW)
  • Leak Detector
  • Column Test Mixture (Reference)
  • Checkout Column
  • Instrument Manuals
solutions
Solutions

Quickest Solution ----

Improve Chromatography ---

Do Manual Integration ---

Get Results out Fast !!

NO!

WRONG ANSWER!!!

solutions30
Solutions
  • 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
does anyone have a question
Does anyone have a question?

Question !

Where do you document your trouble shooting?

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