7th International Symposium on Recent Advances in Food Analysis (RAFA)

The 7th International Symposium on Recent Advances in Food Analysis, better known in short as RAFA, starts this week in Prague, The Czech Republic.  This is my tenth anniversary for this biennial meeting, where the organizer, Jana Hajšlová, invited me to give the lecture, Using the QuEChERS Sample Preparation Method and GCxGC-TOFMS to Determine Pesticides in Baby Foods, back in 2005 at the 2nd RAFA.  One of the main points of that 2005 talk was exploring the use of analyte protectants to quantitatively improve gas chromatography of active pesticides such as omethoate, demeton-S-methyl-sulfone, etc.  Example analyte protectants include volatile sugars that are rich in hydroxy functionalities so that when co-injected at high added concentrations with extracts tie up Si-OH and other active spots in the GC inlet liner and the GC column.  Not surprisingly given the previous literature reports and my discussions with Steve Lehotay at USDA, I found that at low pg levels some active pesticides in the presence of analyte protectants showed almost a 100-fold response factor increase versus solvent-only standards.  Needless to say, when the Maximum Residue Levels for some pesticides in baby food are below 10 ppb, this increase in detectability can be extremely important.

The desire for good instrument sensitivity to determine low pesticide and pollutant residue levels in food and the environment has continued for the last 10 years, and the instrument vendors have made large advances in detecting lower levels, so much so that LC-MS/MS practitioners are expanding their employment of “dilute-and-shoot” methods as a way to avoid ion suppression and other “detector” associated phenomena that lead to sub-par results. While the detectability strides for GC-MS/MS haven’t been as significant, the GC instruments are still getting better (including introduction of APGC and GC-Orbitrap), leading to the possibility of using split injection to relieve some of the GC inlet activity (e.g., omethoate sorption) and reactivity (e.g., captan breakdown) issues faced by residue chemists.  We call split injection, “shoot-and-dilute GC”, and are focusing our presentation efforts at RAFA 2015 on this technique, including two where we compare and contrast split injection and the use of analyte protectants.

Julie Kowalski and Jack Cochran; Shoot-and-Dilute Gas Chromatography-Mass Spectrometry: Polycyclic Aromatic Hydrocarbons Quantification in Tea Using Modified QuEChERS Extraction and No Sample Cleanup

Julie Kowalski and Jack Cochran; Shoot-and-Dilute GC-MS/MS: Use of Split Injection for Pesticide Residue Screening to Prolong GC Inlet Liner and Column Performance

Jack Cochran and Julie Kowalski; Shoot-and-Dilute GC-ECD for Analysis of Problematic Pesticides (including Captan and Folpet)

Jack Cochran, Michelle Misselwitz, and Julie Kowalski; Prolonging GC-MS/MS Performance for Pesticide Analysis: Shoot-and-Dilute Injection and Analyte Protectants (Introduction)

Jack Cochran, Michelle Misselwitz, and Julie Kowalski; Prolonging GC-MS/MS Performance for Pesticide Analysis: Shoot-and-Dilute Injection and Analyte Protectants (Ruggedness for Real World Samples)

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