More pesticides identified using Agilent Pesticide DRS Screening GC/MSD Analyzer with new high efficiency source

Melissa Churley and Bruce Quimby, Agilent Senior Applications Scientists

For comprehensive pesticide screening, analysts need a rapid way to set up their full-scan GC/MS method and confirm that it produces accurate results for hundreds of pesticides in complex matrices. With cost pressures, they are challenged to identify and quantify more pesticides in less time. To address these needs, Agilent provides a complete solution that reduces startup time for trace-level pesticide screening.

The Agilent Pesticide DRS Screening GC/MSD Analyzer, which is based on the Agilent 7890 GC and the Agilent 5977 GC/MSD, enables quick screening and quantitation of large numbers of pesticides and endocrine disruptors in a single analysis. Agilent Deconvolution Reporting Software and a Pesticides and Endocrine Disruptors retention-time-locked database accelerate reporting and increase the number of targets screened. When configured with the new Agilent 5977B GC/MSD with a high efficiency source (HES), this analyzer delivers a greater number of pesticides identified with reduced analysis time.

Reveal many more pesticides with the high efficiency source

Routine analysis of residues in environmental and food samples requires confident identification and low-level detection along with fast reporting. The Agilent GC/MSD Pesticide Analyzer accomplishes each of these needs through use of Deconvolution Reporting Software (DRS), which uses the NIST Automated Mass Spectral Deconvolution and Identification System (AMDIS) program [1], and a Pesticides and Endocrine Disruptors Database [2] to accelerate reporting time and increase the number of targets screened.

In addition, proprietary capillary flow technology (CFT) column backflush shortens cycle time, reduces chemical background, and optimizes uptime. With introduction of the Agilent 5977B GC/MSD equipped with the HES, screening is improved by the increase in the number of ions that are created in the source and transferred into the quadrupole mass analyzer. This increase in response equates to more signal and thus better sensitivity. You find more targets during the screening process with good library matches.

With the Agilent HES, positive identification in food samples at 10 ng/g detection levels is now possible in full-scan mode. We demonstrated this capability by DRS analysis of a tomato QuEChERS extract that had been spiked with more than 200 pesticides at concentrations of 10 and 100 ng/g. These concentrations equate to injection of 10 and 100 pg of each pesticide. At the 10 ng/g level, 38 target compounds were identified using the HES, as opposed to none when using the Extractor EI Source, and almost twice as many were identified at the 100 ng/g level (Table 1).

*Diethyl phthalate, benzophenone
** benzilamide, benzophenone, quintozene metabolite (pentachlorophenyl methyl sulfide), indoxacarb and dioxacarb decomposition product [phenol, 2-(1,3-dioxolan-2-yl)-]
***diethyl phthalate, benzophenone, fonofos, phenol, phthalic acid, di(oct-3-yl) ester, phthalimide, quintozene metabolite (pentachlorophenyl methyl sulfide), indoxacarb and dioxacarb decomposition product [phenol, 2-(1,3-dioxolan-2-yl)-]

Table 1. Number of AMDIS targets identified in tomato spiked at 10 and 100 ng/g using the Extractor EI Source (EXR) and HES. The HES identified significantly more targets.

Figure 1. Analysis of 10 pg flusilazole (m/z 233) in tomato with AMDIS shows excellent match.

In Table 1, the amount of pesticide injected is 10 and 100 pg, respectively. The NIST hit number breakdown (distribution) is given for categories of first, second, and third or greater hit. Identified targets that were not spiked into tomato but had an AMDIS match score ≥ 80 and NIST hit # ≤ 3 are also listed. Tuning conditions for each source are given in parentheses.

Figure 1 shows an example AMDIS analysis for the target flusilazole and includes raw and extracted spectra with the library match for the component. The AMDIS match factor was 84 and the reported NIST reverse match score was 73.

Quickly identify more targets

Fast and accurate screening of pesticides is further improved with the Agilent Pesticide DRS Screening GC/MSD Analyzer, which can now be configured with the new Agilent 5977B GC/MSD with a high efficiency source. When combined with Deconvolution Reporting Software, you can now use full-scan mode to positively identify many targets in food at a concentration as low as 10 ng/g.

If you are ready to replace tedious method development with a fully configured pesticide analyzer, investigate details for the Agilent Pesticide DRS Screening GC/MSD Analyzer.

Acknowledgement

The authors wish to thank Nathan Contino.

References

1. NIST Standard Reference Database 1A, NIST/EPA/NIH Mass Spectral Library (NIST 14) and NIST Mass Spectral Search Program (Version 2.2), User’s Guide.
2. Philip L. Wylie, "Screening for 926 Pesticides and Endocrine Disruptors by GC/MS with Deconvolution Reporting Software and a New Pesticide Library," Agilent publication 5989-5076EN.

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Article Directory – January 2016