TROBLESHOOTING GAS CHROMATOGRAPHY (GC) Parto Zist Behboud Reza Daj 8/16/2014

Today’s Overview Introduction 1 Troubleshooting Approach 2 Pressure Problems 3 Leaks 4 Component Malfunctions 5 Baseline Problems 6 Peak Problems 7 Data Problems 8

Introduction Flow Controller Injection Port Detector Column Oven Column Gas Cylinder Electric Signal Data Processor

T ROUBLESHOOTING A PPROACH Do It Yourself Reference Points Common Problems Safety Getting the Facts Isolating the Source Repair Strategy Preventive Maintenanc e

Split/SplitlessSplit/Splitless1 On-columnInjectionOn-column Injection 2 Programed Temperature VaporizationProgramed Temperature Vaporization 3 Sample Injector System

Detector

Carrier Gas He and N 2 are usually used. (In the case of a capillary column, helium is desirable) The gas of % or more of purity is used. Detector Gas TCD... No need FID... H 2, Air ECD... N 2 (In the case of a packed column, carrier gas is surely N 2. In the case of a capillary column, N 2 is used for makeup gas. ) FTD... H 2, Air FPD... H 2, Air BID... He Carrier Gas and Detector Gas

Pressure Problems High PressureLow Pressure Erratic or Cycling Pressure

Column Pressure 1.Column Length 2.Inner diameter 3.Packing size High Pressure FiltersFilters 1 BuffersBuffers 2

L OW P RESSURE Low Flow ResistanceLow Flow Resistance 1 Low Flow RateLow Flow Rate 2 LeakageLeakage 3

Erratic or Cycling Pressure Low Flow ResistanceLow Flow Resistance 1 APC, AFC MalfunctionAPC, AFC Malfunction 2 Bad ConditionBad Condition 3

Leaks Leaks Location the source Piping Column Fitting Leaks

Column Fitting Leaks

P IPING Piston Seal Tube Fitting Check Valve

Location the source

Component Malfunctions Electronic Problems Injector Problems Column Problems Temperatu re Problem Detector Problem s Flow Problem

With today's complex digital systems. Repairing electronic malfunctions usually requires an expert. But we provides suggestions for things that can be done before calling in an expert. Electronic Problem Fans Fuses Cables Boards

Detector Problems Contamination 1 Gas Purity 2 Leaks 4

Injector Problems Carryover-Manual Injector 1 Septum Condition 2 Glass Insert Contamination 3 Purge 4 Leaks 5

Column Problems Repairs Storage Cleaning Connation

B ASELINE P ROBLEMS Noisy Baselines 1.AFC 2.Gradient Temperature 3.Detector 4.Recorder 5.Data System Drifting or Cycling Baseline 1.Equilibration 2.Late Peaks 3.Temperature 4.Electrical

P EAK P ROBLEMS No Peak or Small PeaksNo Peak or Small PeaksNo Peak or Small PeaksNo Peak or Small Peaks1 Bad Peak ShapeBad Peak ShapeBad Peak ShapeBad Peak Shape2 Extra PeakExtra PeakExtra PeakExtra Peak3 Negative PeakNegative PeakNegative PeakNegative Peak4 Incorrect Retention TimeIncorrect Retention TimeIncorrect Retention TimeIncorrect Retention Time5 Poor ResolutionPoor ResolutionPoor ResolutionPoor Resolution6

B AD P EAK S HAPE Overload Sample Solvent Bad Columns Dead Volume

E XTRA P EAKS Late Peaks Carryover Peaks Ghost Peaks

N EGATIVE P EAKS

U NCORRECTED RETENTION TIME The Column The Eluent Temperature Equilibration

P OOR R ESOLUTION Theory Efficiency N Selectivity Retention K

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