Using HRAM for Pesticide Workflows

While LC-QqQ tandem MS enables highly selective and sensitive quantitation and identification of hundreds of target pesticides in a single run, this approach requires extensive compound-dependent parameter optimization and cannot be easily adapted to screen for untargeted pesticides.

Full scan approaches, on the other hand, are able to screen for a much broader range of analytes, meaning the search is not limited to a pre-defined list of chemical suspects. With the right analytical tools, unexpected analytes can be identified and quantified at the same time as performing routine targeted and quantitative analyses.

However, as full scan approaches produce significantly more data than conventional approaches, it is essential to use data analysis software that can rapidly process results and cross reference against spectral libraries and compound databases in order to make sense of all this information. These software can quickly and automatically search online compound databases such as ChemSpider and mzCloud, or a laboratory’s own database of analytes, to determine empirical formulae or tentatively identify unknown compounds.

Boosting Laboratory Efficiency

With ever increasing numbers of residues to identify, food testing laboratories require robust, reliable, and efficient technologies that enable high productivity. And with budgets a key priority for many lab managers, these analyses must also be performed at a very low cost per sample.

One of the benefits of multi-residue screening based on HRAM Orbitrap MS is the ability to analyze multiple components simultaneously. Combining multiple pesticide workflows in a single run can help laboratories work more efficiently, increasing throughput and boosting productivity. Full scan approaches also allow laboratories to combine pesticide workflows with other types of analyte workflows, such as toxins and veterinary drugs. This way, laboratories can expand the analytical reach of their food testing workflows while minimizing the time and resources spent preparing samples for separate analyses. Furthermore, as HRAM Orbitrap MS approaches also facilitate retrospective analysis, analytes that are not currently on target lists can be identified at a later date without having to store and re-analyze samples.

In addition to advanced hardware, innovative informatics can also streamline workflows and boost productivity. Many forward-looking laboratories are using integrated method development and data analysis solutions that allow operators to conveniently modify pre-configured methods depending on the matrix or analytes of interest. Used in conjunction with cloud-based spectral library and compound database searching, these integrated software solutions can help minimize the time taken between sample injection and the analyst reaching a conclusion.

Simplifying Residue Extraction

One of the most important stages in pesticide quantitation is residue extraction. While full scan analysis workflows are able to screen large numbers of analytes faster and more efficiently than conventional QqQ techniques, they can only do this if the residues they are analyzing are fully extracted from the food matrix in the first place—and if the analytes are chromatographed and ionized.

In recent years, the widespread adoption of extraction techniques such as QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) have simplified the preparation of high-moisture food samples and overcome many of the limitations of conventional approaches. Early approaches typically involved the use of multiple, time-consuming procedures, and produced results that were highly matrix dependent. The QuEChERS method, on the other hand, is based on a single acetonitrile extraction step, with an optional dispersive solid-phase extraction clean-up step. However, although the method is generic, simple to implement, and amenable to a wide range of food samples, the extracts often contain high concentrations of co-extractives.

The latest separation technology is simplifying sample preparation. The Thermo Scientific TurboFlow inline clean-up technique, for example, is a complementary sample preparation approach that eliminates up to two-thirds of the steps required by traditional methods, permitting the injection of complex matrices directly into the instrument. Analytes are separated from the matrix using specialized chromatography columns packed with large particles that retain residues while larger molecules, such as lipids and proteins, pass through. The residues of interest can then be transferred to an analytical column and subsequently analyzed.