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The use of the analytical methods described in previous sections provides sensitive and reliable methods that allow for low LOQs and suitable recoveries, as it can be observed in Tables 1.1–1.4. Thus, despite the lower EQS set by EU legislation for some pesticides, lower LOQs can be achieved and, for instance, concentrations down to 0.0001 µg l⁻¹ can be quantified (see Table 1.1), combining preconcentration techniques, such as SPE or SPME and sensitive analyzers. For instance, 51 pesticides, covering highly polar compounds, were determined in surface and groundwaters by using on-line SPE in combination with (U)HPLC and tandem mass spectrometry, providing LOQ values in the range of 0.005–0.025 µg l⁻¹ [78]. Higher limits were obtained in soils, allowing the quantification at µg kg⁻¹ or even lower (see Table 1.2), as well as in biota, where concentrations below µg kg⁻¹ (ng g⁻¹) can be detected (Table 1.3). Additionally, the use of passive sampling, such as in air, allows for achieving adequate recovery and precision values (Table 1.4) and low LOQs (< 6.5 pg m⁻³) for most of the compounds [56].

In terms of recovery, most of the current analytical methods provided recoveries between 70% and 120%, although when multiresidue methods are developed, recoveries < 70% or > 120% are sometimes achieved. In the case of lower recoveries, if precision is < 20%, correction factors can be used for quantification purposes. In this sense, the use of generic methods, such as QuEChERS, which has been widely used in soils (see Table 1.2), provides acceptable recoveries (70–120%) for the simultaneous environmental monitoring of 218 pesticide residues in clay loam soil [99], or the quantitative extraction of parent pesticides, such as afidopyropen, and metabolites (recovery values: 85–100%) [98].