Automated sample preparation for pesticides using QuEChERS extraction and cleanup

The QuEChERS analysis method is a popular solid-phase extraction method used for the analysis of pesticide residues in food. The extraction part is standardized by the official methods EN 15662 and AOAC 2007.01, however, limitations of the method arise in the cleanup steps, analytically and for the lab logistics.

This free SelectScience^® webinar, now available on demand, introduces automated sample processing of the QuEChERS analysis method for pesticides. Dr. Hans-Joachim Huebschmann, Gwen Lim and Chiew Mei Chong present two workflow variations for high sample throughput in online GC-MS and LC-MS analysis and demonstrate the integration of the QuEChERS extraction.

Read on for highlights of the Q&A session, and register now to watch the webinar on demand.

Is uSPE a recently developed method or is it already used in routine?

HJH: It has been used in many food pesticides laboratories for many years. We see online installations with GC-MS, but also offline installations in labs with many mass specs.

What cost per sample needs to be considered using uSPE?

HJH: For the cost per sample, the complete workflow needs to be considered. The cost of the cartridge compares to the sorbent materials used in dSPE. The benefit is in the logistics, not having to keep different kinds of sorbent materials available for different food commodities, and the preparation and proper use of such mixes.

On top of that, the cleanup is more efficient and leads to less preventive maintenance of the GC-MS and LC-MS for longer sample series. So, there is less downtime of the instruments and less manual work. Also, the sample series can be run unattended overnight.

Which sorbent materials are used in the cartridges?

GL: The current cartridges follow the recommendation and optimization done by Bruce Morris and Richard Schriner from Hill Labs, published in 2015.

For the GC-MS analysis, we use PSA with C18 and MgSO₄, with a small portion of CarbonX material. In the cartridge for LC-MS analysis, the PSA material is replaced by Z-Sep material and does not contain MgSO₄.

I work with analytes other than pesticides. Can we get cartridges with different sorbent materials?

CMC: Yes, that is possible. We provide cartridges using customized sorbent materials as well. Please get in touch with us directly to discuss your needs.

How is the uSPE solution ordered with a PAL System?

GL: There is a uSPE kit available for the PAL System. The uSPE kit contains the trayholder with the shown racks, the shown workflow with detailed standard operating procedures (SOP), vials, and a set of cartridges.

Does the uSPE workflow allow standards to be added?

CMC: Yes, that is possible. The workflow offers the possibility to add internal standards before or after the uSPE cleanup. Also, you can use a syringe sandwich injection to add standards or analyze protectants. Such various functions are optional in the workflow.

Can I use the cartridge multiple times?

GL: We do not recommend this. The principle of the cleanup is that the matrix is retained on the uSPE cartridge. It would also be necessary to flush the matrix from the cartridge, but there are no data on the performance for additional samples.

Does the uSPE work for difficult matrices such as spices?

CMC: Yes, this is possible. Arnab Goon from the National Referral Laboratory in India has done a study into uSPE cleanup of turmeric, chili, and red wine. The group has shown that the uSPE cartridge can work efficiently for a wide range of spices with no specific requirements of clean-up optimization for individual matrices.

If we do the extraction step as well on a PAL System, how can we add buffer salts and sodium chloride?

CMC: We recommend preparing the buffer salts in empty 2 mL vials. The PAL System can then add saturated NaCl solution, MeCN, and the liquid sample. Solid samples need to be weighed into the vials beforehand.

Can we modify the workflow as needed using the PAL Method Composer?

CMC: Yes, that’s possible. The PAL Method Composer is a graphical tool easy to use for users. Additional steps like standard or extract dilutions or even the buildup of calibration curves can be added to the workflow by the user.

To learn more about the PAL System, watch the webinar on demand >>
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