Experts Webinar Series: GC-MS/MS Pesticide Method Development and Pesticide Testing in Food

Secrets for Successful GC-MS/MS Pesticide Method Development

Devil is in the details in many cases, and this is very true for successful GC-MS/MS method development. When developing, adopting or even just implementing GC-MS/MS methods in pesticide residue and other trace-level routine analysis, there are many details and parameters that need to be considered. For example, no GC analysis would be successful without properly optimized injection conditions. Tandem mass spectrometry (MS/MS) can provide improved detection selectivity, which is crucial for low-level analysis in complex food and dietary supplement matrices. However, the use of MS/MS does not guarantee success unless the precursor and product ions are properly selected and evaluated in target matrices, which may often involve a compromise between detection selectivity and sensitivity. And even with very good detection selectivity without any observed matrix interferences, sample matrix can have other negative effects on the routine method performance, affecting quantitation accuracy due to matrix effects (mostly response enhancement) or ruggedness due to increasing system contamination and resulting activity. Fortunately, there are some practical tools and techniques that can help us deal with these issues and minimize these effects, such as the use of column backflushing or co-injecting compounds (analyte protectants) that help deactivate the GC system in every injection.

Learning Objectives:

• Tips & tricks for optimization of GC-MS/MS method parameters
• Practical tools for minimizing detrimental matrix effects in routine GC-MS/MS analysis

Presenter: Katerina Mastovska PhD (Chief Scientific Officer, Eurofins Scientific, US Food Division)

Dr. Katerina (Kate) Mastovska is a Chief Scientific Officer at Eurofins US Food Division. She is also the Technical & Industrial Director for Pesticides within the Operational Best Practices Program at Eurofins Scientific, piloting a global team of experts from Eurofins pesticide testing laboratories. Kate is a Fellow of the AOAC International and the recipient of the 2021 AOAC Harvey W. Wiley Award. Among other activities at the AOAC, she is an Official Methods Board member and a former co-chair of the AOAC Chemical Contaminants and Residues Community. Kate has been involved in chromatographic and mass spectrometric analysis of chemical residues, contaminants and adulterants for over 25 years and authored/co-authored more than 70 scientific publications in that area.

Rapid Rinse and Shoot: A Screening Workflow for Pesticides in Fruit by GC/MS in Under Six Minutes

A fast screening workflow for residual pesticides present on the surface of fruits was enabled using the Agilent Intuvo 9000/5977B GC/MS system, featuring a GC oven with direct heating technology and MS spectral deconvolution. Residual pesticides were rinsed from the tested commodity surface with acetone. The rinsate was collected and injected into the GC/MSD system. The direct heating oven allowed for a very high temperature program rate (250 C/min) to complete the GC/MS analysis in 3.4 minutes. Spectral deconvolution coupled with the library search algorithm and time-filtering using retention indices resulted in rapid and confident identification of residual pesticides present on the fruit. The NIST 17 spectral library as well as other commercially available and user created libraries can be used for compound identification. The entire analysis from sample collection to reporting took under 6 minutes. The combination of the Intuvo Guard Chip and column backflushing yielded longer maintenance-free uptime. This approach is particularly useful for prioritizing samples in high-throughput facilities for more in depth analysis.

With the hardware employed, the oven ramp rate can be lowered to yield a significant increase in a chromatographic resolution. For example, to more closely evaluate a screening result and increase confidence in compound identification, chromatographic and spectral interference can be reduced by using the slower oven ramp. Moreover, this screening approach can be utilized with a fast air bath oven GC, resulting in the analysis time of 6.4 min.

Learning Objectives:

Discovering a sample triaging workflow that involves simplified sample preparation via rinsing fruit surface with acetone, collecting rinsate, and injecting it into GC/MSD system.

Learning a workflow of compound qualitative rapid and reliable identification using library search of deconvoluted spectra coupled with retention index-based time filtering.

Presenter: Anastasia A. Andrianova (GC/MS Application Scientist, Agilent Technologies, Inc.)

Anastasia Andrianova is a GC/MS Applications Scientist in the Mass Spectrometry Division of Agilent Technologies, located in Wilmington, Delaware. She received a Ph.D. in analytical chemistry from the University of North Dakota (Grand Forks) in 2017 and a combined masters’ and bachelor’s degree in analytical chemistry from the Moscow State University (Moscow, Russia) in 2014. Anastasia has been at Agilent Technologies since 2018. She has authored or co-authored over 30 journal articles and application notes, as well as 1 patent in the field of analytical chemistry, focusing on chromatography and mass spectrometry. Anastasia is currently working in GC/MS applications in multiple areas with a focus on food and environmental analysis.