different mobile-phase composition on separation were discussed. The absolute
configuration of flufiprole enantiomers was measured through the combination of
experimental and predicted ECD spectra. An alumina-N solid-phase extraction
(SPE) column was used in the clean-up of the vegetables, fruits and soil samples.
Average recovery rates of two enantiomers ranged from 87 to 99%. Good linearity
(R(2)>0.998) was obtained for all analyte matrix calibration curves within the range
of 0.2–20 μg/L. The limit of detection for two enantiomers in the six matrices was
0.007–0.008 μg/kg, whereas the limit of quantification of the two enantiomers in
fruits, vegetables and soil was 0.021–0.025 ng/kg.
Supercritical fluid chromatography (SFE) was developed for the investigation of
the enantiomer profile for isofenphos-methyl in corn, nuts and soil (Chen et al.
2016a,
b).
Isofenphos-methyl(propan-2-yl-2-[methoxy-(propan-2-amino)
phosphinothioyl]oxybenzoate), a pesticide used for the control of soil-dwelling
insects, was analysed in spiked wheat, corn, peanut and soil with SFE on a ChiralPak
IA-3 column (CSP: Amylose tris(3,5-dimethylphenylcarbamate) and quantified with
tandem mass spectrometry. A QuEChERs method was adopted for this investigation, and enantiomer-specific recovery rates between 76% and 111% determined.
The limits of detection for both enantiomers varied between 0.02 μg/kg and 0.15 μg/
kg, while the limit of quantification did not exceed 0.50 μg/kg.
The effect of wastewater irrigation and sewage sludge as soil amendments was
investigated for the chiral pesticide benalaxyl (methyl 2-(2,6-dimethyl-N(2-phenylacetyl)anilino)propanoate) with a HPLC/MS method (Jing et al. 2017).
The 148-day long exposure experiment was the basis for the here-performed evaluation. The enantiomer-selective separation was carried out by HPLC-MS/MS with
a chiralpak IC chiral column (CSP: Cellulose tris (3,5-dichlorophenylcarbamate)).
Benalaxyl decreased with half-life of 16.1 days in soil under tap water irrigation with
a preferential residue of S-benalaxyl. Benalaxyl acid was formed with great preference of the R-enantiomer before 21 days while enriched in S-enantiomer afterwards.
The transformation of benalaxyl was restrained by both wastewater and treated
wastewater irrigation, but the enantioselectivity of the S-benalaxyl residue was
enhanced. Benalaxyl acid was also formed with similar enantioselectivity as found
during tap water irrigation. Sewage sludge seems to accelerate benalaxyl transformation with a shorter half-life. Surprisingly, the enantioselectivity with the preferential transformation of the S-enantiomer in sewage sludge was opposite to that in
soil. More benalaxyl acid was generated with EF values always lower than 0.5 and
remained longer in sewage sludge than in soil. A sterilisation experiment indicated
that the conversion of benalaxyl to benalaxyl acid and the enantioselectivity were
determined by the microorganisms in soil or sewage sludge.
The application scope for enantiomer-selective analysis for modern pesticides in
an environmental context is gradually extended both with respect to sample matrices, as well as with chiral target substances.
Currently, comprehensive reports are available on EFs and occurrence of chiral
pesticides in beer (Zhao et al. 2018a, b, c), soils (Gamiz et al. 2016a, b; Zhang et al.
2018a, b; Zhao et al. 2018a, b, c), vegetables (Tian et al. 2015; Wang et al. 2015a, b;
Gao et al. 2016; Zhang et al. 2018a, b), molluscs (Khazri et al. 2016) and many more
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
215
configuration of flufiprole enantiomers was measured through the combination of
experimental and predicted ECD spectra. An alumina-N solid-phase extraction
(SPE) column was used in the clean-up of the vegetables, fruits and soil samples.
Average recovery rates of two enantiomers ranged from 87 to 99%. Good linearity
(R(2)>0.998) was obtained for all analyte matrix calibration curves within the range
of 0.2–20 μg/L. The limit of detection for two enantiomers in the six matrices was
0.007–0.008 μg/kg, whereas the limit of quantification of the two enantiomers in
fruits, vegetables and soil was 0.021–0.025 ng/kg.
Supercritical fluid chromatography (SFE) was developed for the investigation of
the enantiomer profile for isofenphos-methyl in corn, nuts and soil (Chen et al.
2016a,
b).
Isofenphos-methyl(propan-2-yl-2-[methoxy-(propan-2-amino)
phosphinothioyl]oxybenzoate), a pesticide used for the control of soil-dwelling
insects, was analysed in spiked wheat, corn, peanut and soil with SFE on a ChiralPak
IA-3 column (CSP: Amylose tris(3,5-dimethylphenylcarbamate) and quantified with
tandem mass spectrometry. A QuEChERs method was adopted for this investigation, and enantiomer-specific recovery rates between 76% and 111% determined.
The limits of detection for both enantiomers varied between 0.02 μg/kg and 0.15 μg/
kg, while the limit of quantification did not exceed 0.50 μg/kg.
The effect of wastewater irrigation and sewage sludge as soil amendments was
investigated for the chiral pesticide benalaxyl (methyl 2-(2,6-dimethyl-N(2-phenylacetyl)anilino)propanoate) with a HPLC/MS method (Jing et al. 2017).
The 148-day long exposure experiment was the basis for the here-performed evaluation. The enantiomer-selective separation was carried out by HPLC-MS/MS with
a chiralpak IC chiral column (CSP: Cellulose tris (3,5-dichlorophenylcarbamate)).
Benalaxyl decreased with half-life of 16.1 days in soil under tap water irrigation with
a preferential residue of S-benalaxyl. Benalaxyl acid was formed with great preference of the R-enantiomer before 21 days while enriched in S-enantiomer afterwards.
The transformation of benalaxyl was restrained by both wastewater and treated
wastewater irrigation, but the enantioselectivity of the S-benalaxyl residue was
enhanced. Benalaxyl acid was also formed with similar enantioselectivity as found
during tap water irrigation. Sewage sludge seems to accelerate benalaxyl transformation with a shorter half-life. Surprisingly, the enantioselectivity with the preferential transformation of the S-enantiomer in sewage sludge was opposite to that in
soil. More benalaxyl acid was generated with EF values always lower than 0.5 and
remained longer in sewage sludge than in soil. A sterilisation experiment indicated
that the conversion of benalaxyl to benalaxyl acid and the enantioselectivity were
determined by the microorganisms in soil or sewage sludge.
The application scope for enantiomer-selective analysis for modern pesticides in
an environmental context is gradually extended both with respect to sample matrices, as well as with chiral target substances.
Currently, comprehensive reports are available on EFs and occurrence of chiral
pesticides in beer (Zhao et al. 2018a, b, c), soils (Gamiz et al. 2016a, b; Zhang et al.
2018a, b; Zhao et al. 2018a, b, c), vegetables (Tian et al. 2015; Wang et al. 2015a, b;
Gao et al. 2016; Zhang et al. 2018a, b), molluscs (Khazri et al. 2016) and many more
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
215