Measuring Residue Levels

The Analytical Methods and Equipment Used in the Laboratory

Due to the advancement in laboratory analysis work, we now have the capacity to detect extremely low levels of residues.  The main analytical techniques used in the laboratory are:

  • GC-MS/MS - gas chromatography with triple quadrupole mass spectrometer detector and
  • LC-MS/MS - high performance liquid chromatography with triple quadrupole mass spectrometer detectors

The use of triple quadrupole mass spectrometers is ideal for analysing samples for a large number of residues at very high sensitivity.  This ensures that the range and scope of analysis provides the greatest level of protection for Irish consumers. 


The two main types of analytical methods used in the laboratory are:

  • Multi-residue analytical methods

These analytical methods are extremely versatile and broad with a capacity to analyse samples for large numbers of residues.  The current fruit and vegetable method has a scope of ~ 460 different pesticides and metabolites.  The analytical methods used are extremely sensitive with a capacity of detecting pesticide residues at levels down to 10 nanograms per gram in food.  The analysis of samples takes up to 3 days to complete for the full ~460 suite of pesticide compounds.  Turnaround time for samples coming into the laboratory is normally less than 20 working days with in excess of 90% of samples turned around inside this time period. 

  •  Single residue analytical methods

Single residue methods of analysis are required for pesticides, which are not amenable to multi-residue methods. This might be because they require a different extraction, clean-up or analytical column.