Several species
aAbbreviations: d-SPE: Dispersive solid phase extraction; dw: dry weight; ECD: Electron capture detector; GPC: Gel permeation chromatography; LC: Liquid chromatography; MS: Mass spectrometry; MS/MS: Tandem mass spectrometry; OCPs: Organochlorine pesticides; PLE: Pressurized liquid extraction; PSA: Primary secondary amine; Q: Single quadrupole; QqQ: Triple quadrupole; TPs: Transformation products.
bLimit of detection.
Table 1.4 Overview of analytical methods applied to determine pesticides in air matrices.
| Pesticides | Matrix | Extraction technique | Determination technique | Recovery (%) | LOQ (pg m−3) | Reference |
|---|---|---|---|---|---|---|
| 20 | Indoor air | Passive Sampling (VERAM) MAE: acetone:hexane, 1 : 1 v/v Clean-up: Alumina-C18 Cartridges | GC-Q-MS | 59−174 | 1−10b | [51] |
| OCPs | Air samples | PAS: PUF. Soxhlet: acetone | GC-Q-MS | 82−126 | — | [54] |
| 34 (OCPs & CUPs) | Air samples | PUF. Soxhlet: acetone + petroleum ether. Clean-up: silica column | GC-Q-MS | 86−102 | 0.1−90.7c | [55] |
| 40 & TPs | PM10 (remote, urban and rural areas) | MAE: ethyl acetate | LC-QqQ-MS/MS | — | 6.5−32.5 | [57] |
| 35 | PM10 | MAE: Ethyl acetate | UHPLC-Orbitrap | 73−116 | 2.6−75 | [56] |
| 13 | PM2.5 | UAE: 18% of Acetonitrile in dichloromethane | GC-Q-MS | 70.2−124 (ethion 31.2–63.0) | 7.5−60 | [58] |
| 452 (OCPs & CUPs) | Air particles | UAE: dichloromethane | GC-QqQ-MS/MS | — | — | [53] |
aAbbreviations: CUPs: Current-use pesticides; GC: Gas chromatography; LC: Liquid chromatography; MAE: Microwave-assisted extraction; MS: Mass spectrometry; MS/MS: Tandem mass spectrometry; OCPs: Organochlorine pesticides; QqQ: Triple quadrupole; TPs: Transformation products; UAE: Ultrasound-assisted extraction; PAS. Passive air sampler; PUF: Polyurethane foam; UHPLC: Ultra-high-performance liquid chromatography.
bLimit of detection provided as ng VERAM−1.
cLimit of detection.
1.3 Determination of Pesticides
Current analytical methods for pesticide residue analysis are mainly based on the use of chromatographic techniques (GC or LC), depending on their polarity and volatility among other factors, coupled to MS analyzers. As an example, Figure 1.5 shows the chromatograms of a blank soil sample spiked with 218 pesticides by LC-MS/MS and GC-MS/MS, observing the potentiality of these techniques to analyze a wide range of compounds.
Figure 1.5 Chromatograms of the targeted pesticides by LC-MS/MS (A) and GC–MS/MS (B) of a blank soil sample spiked at 20 ng g−1. Source [99]. Reproduced with permission of Elsevier B.V.
1.3.1 Development of the Instrumental Method
1.3.1.1 Chromatography
GC enables the detection of a high number of volatile or semivolatile and thermally stable pesticides, allowing the determination of persistent pesticides in environmental matrices such as water, soil, biota and air (Tables 1.1–1.4). Several multiresidue methods have been developed and, for instance, 11 OCPs were determined in soils using GC with a DB-5-MS capillary column with 5% phenyl stationary phase and 95% of methylpolysiloxane [106]. Although this is the stationary phase most commonly used, other stationary phases, such as DB-XLB and DB-35-MS, were also tested for the determination of endosulfan, chlorpyrifos and their metabolites [29], obtaining the best results with DB-XLB (larger differences in the retention time of the compounds). ZB-5MSi was also tested to determine pyrethroid pesticide metabolites in soil samples [64] and a HP-5-MS UI column to analyze 58 pesticides in soil samples [61]. Additionally, pesticides can simultaneously be analyzed with other pollutants such as polycyclic aromatic hydrocarbons (PAHs), brominated diphenyl ethers (BDEs) and polychlorinated biphenyls (PCBs) in environmental matrices, such as surface waters [84], accomplishing this with the Environmental Quality Standards (EQS) fixed by Directive 2013/39/EC [10].
For non-GC amenable compounds, although chemical derivatization can be carried out, LC is recommended and liquid chromatography (LC) and, increasingly, ultra-high-performance liquid chromatography (UHPLC) are commonly used for the analysis of pesticides, using different particle sizes as 5 µm [107], 3 µm [62] or even lower (1.8 µm) [28]. For LC-amenable pesticides, conventional C18 columns are commonly used [57], with generic mobile phases such as methanol and water 0.1% formic acid 4 mm ammonium formate, allowing, for instance, the determination of parent pesticides (famoxadone) and metabolites [28]. Moreover, hydrophilic interaction
