from different solid matrices including soil. It consists of extracting pesticide with an
aqueous-miscible solvent (e.g., acetonitrile) in the presence of high amounts of salts
(e.g., sodium chloride and magnesium sulfate) and/or buffering agents (e.g., citrate)
to induce liquid phase separation and stabilize acid and base-labile pesticides. Upon
shaking and centrifugation, an aliquot of the organic phase is subjected to further
cleanup using SPE. Then, the mixture is centrifuged, and the resulting supernatant
either can be analyzed directly or can be subjected to minor further treatment before
analysis. The method is simple, rapid, and inexpensive with reduced reagent use. Yu
et al. developed a multi-residue method for pesticides, including pyrethroids, in soil
using QuEChERS sample preparation method. 5 g of soil were extracted with 10 mL
acetonitrile with 1% acetic acid. 4 g anhydrous MgSO4 and 1 g sodium acetate
(NaOAc) were added, and the mixture was shaked [35]. Then, the supernatant was
treated with 900 mg MgSO4, and 150 mg PSA and 150 mg C18 were used as
sorbents. Recoveries were of 88–96% with MLODs 0.3–5 μg/kg [35].
2.3 Extraction from Air Samples
Pyrethroids were successfully extracted from air samples by SPE method with
Chromosorb 106 and Tenax TA as adsorbents and ethyl acetate as eluent [36]. Recoveries were 67% and 117% with both materials [36]. In indoor dust, pyrethroids were
extracted by microwave-assisted solvent extraction (MASE) followed by Florisil
cleanup. The aqueous phase was 1 M sulfuric acid solution containing ascorbic
acid, whereas the nonpolar organic phase was hexane. Recoveries were 84–101%
and MLODs 1–7 ng/g [37]. Sonication was also performed for extraction of pyrethroids from house dust samples, followed by cleanup using SPE (C18 cartridge). The
recovery range was 51–101% with MLODs of 1–60 ng/g [38]. A method based on the
combination of SPE and SPME for the analysis of pyrethroids in indoor air was
developed [39]. First, air was pumped through a very small amount of Florisil
(60–100 μm mesh) to retain the target analytes. Then the adsorbent, enriched with
the target analytes, was transferred to a 10 mL glass vial in the presence of 100 μL of
acetone and sealed with a cap. The vial was placed into a water bath at 100
C. The
compounds retained by the adsorbent were extracted by exposing an SPME fiber to
the HS of the vial (HS-SPME) for a fixed period of time. The fiber was then inserted
into the injector port, and pyrethroids were desorbed into the GC for 5 min. Recoveries were of 77–111% with MLODs of 0.083–4.6 ng/m
3 [39].
2.4 Extraction from Biological Samples
Deltamethrin was extracted from biological tissue (liver, kidney, and brain) by
mixing the tissue sample with acetonitrile, centrifuging, and injecting directly the
supernatant onto the LC column [40]. Recoveries from the liver, kidney, and brain
Analytical Methods for Determining Pyrethroid Insecticides in Environmental and. . .
33
aqueous-miscible solvent (e.g., acetonitrile) in the presence of high amounts of salts
(e.g., sodium chloride and magnesium sulfate) and/or buffering agents (e.g., citrate)
to induce liquid phase separation and stabilize acid and base-labile pesticides. Upon
shaking and centrifugation, an aliquot of the organic phase is subjected to further
cleanup using SPE. Then, the mixture is centrifuged, and the resulting supernatant
either can be analyzed directly or can be subjected to minor further treatment before
analysis. The method is simple, rapid, and inexpensive with reduced reagent use. Yu
et al. developed a multi-residue method for pesticides, including pyrethroids, in soil
using QuEChERS sample preparation method. 5 g of soil were extracted with 10 mL
acetonitrile with 1% acetic acid. 4 g anhydrous MgSO4 and 1 g sodium acetate
(NaOAc) were added, and the mixture was shaked [35]. Then, the supernatant was
treated with 900 mg MgSO4, and 150 mg PSA and 150 mg C18 were used as
sorbents. Recoveries were of 88–96% with MLODs 0.3–5 μg/kg [35].
2.3 Extraction from Air Samples
Pyrethroids were successfully extracted from air samples by SPE method with
Chromosorb 106 and Tenax TA as adsorbents and ethyl acetate as eluent [36]. Recoveries were 67% and 117% with both materials [36]. In indoor dust, pyrethroids were
extracted by microwave-assisted solvent extraction (MASE) followed by Florisil
cleanup. The aqueous phase was 1 M sulfuric acid solution containing ascorbic
acid, whereas the nonpolar organic phase was hexane. Recoveries were 84–101%
and MLODs 1–7 ng/g [37]. Sonication was also performed for extraction of pyrethroids from house dust samples, followed by cleanup using SPE (C18 cartridge). The
recovery range was 51–101% with MLODs of 1–60 ng/g [38]. A method based on the
combination of SPE and SPME for the analysis of pyrethroids in indoor air was
developed [39]. First, air was pumped through a very small amount of Florisil
(60–100 μm mesh) to retain the target analytes. Then the adsorbent, enriched with
the target analytes, was transferred to a 10 mL glass vial in the presence of 100 μL of
acetone and sealed with a cap. The vial was placed into a water bath at 100
C. The
compounds retained by the adsorbent were extracted by exposing an SPME fiber to
the HS of the vial (HS-SPME) for a fixed period of time. The fiber was then inserted
into the injector port, and pyrethroids were desorbed into the GC for 5 min. Recoveries were of 77–111% with MLODs of 0.083–4.6 ng/m
3 [39].
2.4 Extraction from Biological Samples
Deltamethrin was extracted from biological tissue (liver, kidney, and brain) by
mixing the tissue sample with acetonitrile, centrifuging, and injecting directly the
supernatant onto the LC column [40]. Recoveries from the liver, kidney, and brain
Analytical Methods for Determining Pyrethroid Insecticides in Environmental and. . .
33