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GC Troubleshooting and Maintenance class room course
1 Day Course | GC Level 2

A logical approach to GC Troubleshooting and Maintenance is explored in this one-day course. Commonly encountered problems and best practices are examined for all major system components including gas handling, inlet system, oven, column and detector.

Examination of separation chemistry, interrogation of poor peak shape and retention problems are a fundamentally important part of the course, leading to increased awareness of troubleshooting principles.

 
  • We limit numbers to 20 per course so that each delegate gets the opportunity to ask questions and fully participate in tutorial exercises
  • When delivered on-site we can design the course material to suit your specific training needs
  • Customisable written assessments are available if required

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download course pdfBest practice for instrument maintenance and column handling as well as routines for cleaning and deactivating inlet and detection systems is discussed to aid the user in prolonging the intervals between essential system maintenance.

In-depth treatments of the causes of peak shape and baseline anomalies are fully covered.
This course is invaluable to anyone who wishes to gain further insight into the problems associated with GC analysis. The content is not instrument-specific.


Who is this course for

This course is designed for those relatively new to GC and ideally will follow-on from attendance to the Fundamental GC training course.

Previous knowledge

Some previous knowledge of gas chromatography and basic experience are recommended but not essential.

What you will learn

  • How the chromatographic process takes place
  • The architecture of a GC system
  • Working principles and problems associated with each component of the system
  • How to use chromatograms to troubleshoot chromatographic problems
  • Best practices for column use and care
  • Best practice in system maintenance and performance evaluation

Approaches to Logical Troubleshooting

  • Logical troubleshooting
  • System overview
  • Component perspective
  • Symptomatic perspective
  • System maintenance records
  • Symptom/Causes/Diagnosis & solution
 

Symptomatic Perspective: Baselines

  • Baseline spikes
  • Noisy baselines
  • Cycling baselines
  • Rising/falling baselines

Component Perspective

  • What to look for/what can go wrong with…
  • Injectors: on-column, split – splitless, large volume
  • Detectors: FID, ECD, NPD, FPD
  • Temperature and pressure control
 

Symptomatic Perspective: Peaks

  • No peaks
  • Fronting/tailing peaks
  • Split peaks/shoulders
  • Broad shoulders
  • Ghost peaks
  • Retention stability
  • Solvent incompatibility
  • Loss of sensitivity

Columns

  • Installation and conditioning
  • Operating principles
  • Optimisation
  • Operating range/bleed
  • Band broadening
 

Maintenance

  • Maintenance schedules
  • Correct maintenance procedures injectors and detectors

Training Calendar

Click on a title below to download a detailed course description or click a date and book your course.

Can't find a suitable training course? Call 01357 522 961 or email us.

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CHROMacademy

Sample Discrimination

The phenomenon of sample discrimination leads to a non-representative sample entering the analytical column compared to the original sample

Sample discrimination is best described using the example on the ‘Graph’ button opposite, which shows the detector response to an injection of n-alkanes at equal concentration. The normalised line shows the original sample composition, and the expected response for each of the n-alkanes. The more highly volatile n-alkanes show total recovery, however for C 25, only half of the analyte present in the sample is introduced into the column, and the recovery of C 37 is less than 25%.

For higher boiling (less volatile) analytes, the residence time of the syringe needle is too short. The analyte will condense on the cold inner and outer surfaces of the needle – prior to it being withdrawn from the inlet. Some less volatile analytes may never properly volatilise and the sample passes the split point (head of the capillary column) as a mixture of sample vapour and non-uniform liquid droplets. Several approaches to the problem have been postulated including:

  • Optimisation of liner geometry and packing materials to promote sample mixing and volatilisation
  • Optimising the injection routine (filled needle, hot needle, solvent flush, air flush, sandwich method etc.)
  • Improved instrument design to reduce fluctuations in split flow
In general, the least amount of discrimination is obtained if the injection is performed as rapidly as possible. For this reason, fast autosamplers generally give less discrimination than manual injection.

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