N-Nitrosamine Impurities in Ethalfluralin: Determination of an Overlooked Deleterious Source in Pesticides

N-nitrosamines are a class of carcinogenic chemical compound. Considering the large-scale application agrochemicals globally, elimination from pesticides should be priority for manufacturers and regulators. A set methods was developed validated determination toxicologically relevant N-nitrosamine impurity ethalfluralin (ethyl-N-(2-methylallyl) N-nitroso amine—EMANA) in 33% w v−1 emulsifiable concentrate (EC) formulations. Solid Phase Extraction (SPE) compared with “dilute shoot” approach. Gas chromatography (GC) combined Flame Ionization Detection (FID) mass spectrometry (MS). For MS, two filtering modes (Selective Ion Monitoring—SIM, tandem spectrometry—MS/MS) ionization (Electron Ionization—EI, Positive ionization—PCI) were applied. It concluded that, case samples high nitrosamine concentration (>90 μg g−1), approach can applied without compromising quality results. SPE, however, is required to attain LOQ (0.33 g−1) good recovery (97.4–110.67%), linearity (R > 0.99) precision (%RSD 0.68–1.74). The supersedes limit by EFSA (1 Technical Active Substance—TAS. range 0.05–110 g−1. official surveillance program Greek market.