used, good repeatability, low cost, and having very high pre-concentration factors.
Chang et al. analyzed eight pyrethroids in tap water, well water, and river water by
LLME using 1-dodecanol as extraction solvent. Recoveries were 79–114% and
MLOD 2.0–50 ng/L [18]. Ultrasound-assisted emulsification-extraction (UAEE) is
another environmentally friendly analytical methodology that can be applied for
extraction and pre-concentration of a wide range of pyrethroids prior to GC-MS
analysis. Feo et al. used chloroform (1 mL) as immiscible solvent for extraction of
pyrethroids from river water samples. Recoveries were of 63–100% and MLODs of
0.03–35.8 ng/L [29]. A novel green enrichment method for pyrethroid
pre-concentration was temperature-controlled ion liquid-dispersive liquid-phase
microextraction (TILDLME) which was developed by Zhou et al. [28]. An ionic
liquid is used as extraction solvent dispersing it in the aqueous solution under the
drive of temperature. The analytes will more easily migrate into the ionic liquid
phase because of the much larger contact area than that of conventional single drop
liquid microextraction. The method was validated on tap water, groundwater, river
water, and reservoir water samples filtered through 0.45 μm micropure membrane.
Recoveries were 77–136% and MLODs of 280–600 ng/L [28]. Pyrethroid extraction
by SPE was realized on an Oasis HLB cartridge with subsequent elution with
methanol (MeOH)/acetonitrile (ACN) (50/50 v/v) [19]. Recoveries were of
70–103% for pre-filtered (using 0.45 μm PTFE fiberglass filters) water samples
and claim MLODs of 5.0 Â 10
À4
–1.5 Â 10
À2 ng/L [19]. C18 cartridge was also
applied to pre-concentrate pesticide traces in both unfiltered groundwater and seawater samples adding organic modifiers (methanol or acetonitrile) to water and using
hexane as solvent [20]. Recoveries were of 80–115%, and MLODs were of
0.3–0.7 ng/L and 0.7–1.5 ng/L for seawater and groundwater samples, respectively
[20]. The major drawback of SPE is large sample volume (e.g., >500 mL) required.
For this reason, miniaturized methods (SPME and SBSE) which are simple, solventless techniques were introduced [54, 55]. Parrilla Vazquez et al. developed a
procedure for SPME analysis of pyrethroids in unfiltered groundwater, using
polydimethylsiloxane/divinylbenzene (PDMS/ DVB 60 μm) as the most appropriate
fiber coating [21]. The sample solution was buffered to pH 3 using a phosphate
buffer, and the solution was kept at 65 Æ 2
C for 30 min. Recoveries were 92–109%
with MLODs of 3–9 ng/L [21]. Bondarenko found analyzing sediment pore water
recoveries of 56–119% with similar MLODs (30 μm PDMS fiber; 20 min stirring at
600 rpm) [22]. Casas et al. studied the influences (e.g., temperature, fiber coating,
salting out effect, and sampling mode) on the efficiency of pyrethroid extraction
from unfiltered water samples [23]. The best conditions were found to be using
PDMS fibers, direct sampling (D-SPME), at 50
C with an exposure time of only
20 min and without adding salt. The recoveries were 81–125% with MLODs of
0.05–2.18 ng/L [23]. A novel solid-phase microextraction (SPME) fiber coated with
multiwalled carbon nanotubes/polypyrrole (MWCNTs/Ppy) was prepared with an
electrochemical method and used for the extraction of pyrethroids in natural water
samples. The results showed that the MWCNTs/Ppy-coated fiber was more effective
and superior to commercial PDMS and PDMS/DVD fibers in extracting pyrethroids
in natural water samples. Recoveries were of 83–112%, and MLODs were within the
30
M. L. Feo
Chang et al. analyzed eight pyrethroids in tap water, well water, and river water by
LLME using 1-dodecanol as extraction solvent. Recoveries were 79–114% and
MLOD 2.0–50 ng/L [18]. Ultrasound-assisted emulsification-extraction (UAEE) is
another environmentally friendly analytical methodology that can be applied for
extraction and pre-concentration of a wide range of pyrethroids prior to GC-MS
analysis. Feo et al. used chloroform (1 mL) as immiscible solvent for extraction of
pyrethroids from river water samples. Recoveries were of 63–100% and MLODs of
0.03–35.8 ng/L [29]. A novel green enrichment method for pyrethroid
pre-concentration was temperature-controlled ion liquid-dispersive liquid-phase
microextraction (TILDLME) which was developed by Zhou et al. [28]. An ionic
liquid is used as extraction solvent dispersing it in the aqueous solution under the
drive of temperature. The analytes will more easily migrate into the ionic liquid
phase because of the much larger contact area than that of conventional single drop
liquid microextraction. The method was validated on tap water, groundwater, river
water, and reservoir water samples filtered through 0.45 μm micropure membrane.
Recoveries were 77–136% and MLODs of 280–600 ng/L [28]. Pyrethroid extraction
by SPE was realized on an Oasis HLB cartridge with subsequent elution with
methanol (MeOH)/acetonitrile (ACN) (50/50 v/v) [19]. Recoveries were of
70–103% for pre-filtered (using 0.45 μm PTFE fiberglass filters) water samples
and claim MLODs of 5.0 Â 10
À4
–1.5 Â 10
À2 ng/L [19]. C18 cartridge was also
applied to pre-concentrate pesticide traces in both unfiltered groundwater and seawater samples adding organic modifiers (methanol or acetonitrile) to water and using
hexane as solvent [20]. Recoveries were of 80–115%, and MLODs were of
0.3–0.7 ng/L and 0.7–1.5 ng/L for seawater and groundwater samples, respectively
[20]. The major drawback of SPE is large sample volume (e.g., >500 mL) required.
For this reason, miniaturized methods (SPME and SBSE) which are simple, solventless techniques were introduced [54, 55]. Parrilla Vazquez et al. developed a
procedure for SPME analysis of pyrethroids in unfiltered groundwater, using
polydimethylsiloxane/divinylbenzene (PDMS/ DVB 60 μm) as the most appropriate
fiber coating [21]. The sample solution was buffered to pH 3 using a phosphate
buffer, and the solution was kept at 65 Æ 2
C for 30 min. Recoveries were 92–109%
with MLODs of 3–9 ng/L [21]. Bondarenko found analyzing sediment pore water
recoveries of 56–119% with similar MLODs (30 μm PDMS fiber; 20 min stirring at
600 rpm) [22]. Casas et al. studied the influences (e.g., temperature, fiber coating,
salting out effect, and sampling mode) on the efficiency of pyrethroid extraction
from unfiltered water samples [23]. The best conditions were found to be using
PDMS fibers, direct sampling (D-SPME), at 50
C with an exposure time of only
20 min and without adding salt. The recoveries were 81–125% with MLODs of
0.05–2.18 ng/L [23]. A novel solid-phase microextraction (SPME) fiber coated with
multiwalled carbon nanotubes/polypyrrole (MWCNTs/Ppy) was prepared with an
electrochemical method and used for the extraction of pyrethroids in natural water
samples. The results showed that the MWCNTs/Ppy-coated fiber was more effective
and superior to commercial PDMS and PDMS/DVD fibers in extracting pyrethroids
in natural water samples. Recoveries were of 83–112%, and MLODs were within the
30
M. L. Feo