Chiracel-OD and AD columns (Zhang et al. 2012a, b, c). This method was applied to
toxicity tests by means of Daphnia magna (details see Chap. 10).
The oxadiazine pesticide indoxacarb (IUPAC: Methyl 7-chloro-2,5-dihydro-2[[(methoxycarbonyl)[4-(trifluoromethoxy)phenyl]amino]carbonyl]indeno[1,2-e]
[1,3,4] oxa-diazine-4a(3H )-carboxylate) is a chiral compound mainly applied as a
fast insecticide or ant-bait in a domestic context for combating ants, cockroaches and
other insect pests. Indoxacarb has been in the scientific focus as environmental
pollutant ever since it was introduced to the global market (McCann et al. 2001;
Mojtahedi et al. 2007; Cheng et al. 2010; Sun et al. 2012a, b; Urvashi et al. 2012). In
the here-reported investigation, the enantioselective transformation and potential
enantiomerisation of indoxacarb was elucidated in two soils under non-sterilised
and sterilized conditions using a ChiralCel OD-RH column (CSP: Cellulose tris
(3,5-dimethylphenylcarbamate)) on RP HPLC/MS (Sun et al. 2013). Under
non-sterilised conditions, the degradation of indoxacarb in two soils was markedly
enantioselective. In acidic soil, the half-lives of R-(À)- and S-(+)-indoxacarb were
10 and 14 days, respectively. Acidic soil was preferential to the degradation of R(À)-indoxacarb. In alkaline soil, the half-lives of R-(À)- and S-(+)-indoxacarb were
12 and 5 days, respectively. S-(+)-indoxacarb was preferentially transformed. Under
sterilised conditions, approximately 5–10% of the initial concentration degraded
after 75 days of incubation in acidic soil, whereas in alkaline soil, approximately half
of the initial concentration was transformed mainly due to chemical hydrolysis.
Enantiomerisation was discovered both for acidic and alkaline soils. Thus, the
mutual transformation between two enantiomers must be considered when evaluating environmental fate. The S-(+)-indoxacarb had a significantly higher inversion
rate compared to R-(À)-indoxacarb.
An extended research program on indoxacarb and cis-epoxiconazole
(1-[[(2S,3R)-3-(2-chlorophenyl)-2-(4-fluorophenyl)oxiran-2-yl]methyl]-1,2,4triazole) was performed on Chinese tea types, tea infusions and corresponding soil
samples (Zhang et al. 2014a, b, c). Separation of the analytes was performed on a
chiral stationary phase using high-performance liquid chromatography (RP-HPLC)
with a Lux 3μ Cellulose-1 (Phenomenex, CSP: cellulose tris
(3,5-dimethylphenylcarbamate)) and with tandem quadrupole time-of-flight mass
spectrometry (Q-TOF/MS) detection. For the various teas (green tea, black tea and
pure tea), fresh tea leaf, soil and black tea infusion samples spiked at low, medium
and high levels, average recovery rates for the four enantiomers were found between
61% and 130%. The limits of detection (LODs) for all four target enantiomers were
1.4 μg/kg or below in the different teas and soil samples and even <0.05 μg/kg in the
black tea infusion. The here-developed method was used for real tea sample screening (Zhang et al. 2014a, b, c).
The antiviral agent and pesticide dufulin (IUPAC: diethyl(αRS)-[2-fluoro-α[(4-methyl-1,3-benzothiazol-2-yl)amino]methyl] phosphonate) was investigated
with focus on enantiomer-selective hydrolysis and photochemical transformation
(Zhang et al. 2013a, b). Dufulin is a novel, antiviral agent which is also used as
insecticide (ant-bait) in domestic homes. Furthermore, this compound is widely used
in China to prevent and control viral diseases in tobacco, vegetable and rice. The
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
213
toxicity tests by means of Daphnia magna (details see Chap. 10).
The oxadiazine pesticide indoxacarb (IUPAC: Methyl 7-chloro-2,5-dihydro-2[[(methoxycarbonyl)[4-(trifluoromethoxy)phenyl]amino]carbonyl]indeno[1,2-e]
[1,3,4] oxa-diazine-4a(3H )-carboxylate) is a chiral compound mainly applied as a
fast insecticide or ant-bait in a domestic context for combating ants, cockroaches and
other insect pests. Indoxacarb has been in the scientific focus as environmental
pollutant ever since it was introduced to the global market (McCann et al. 2001;
Mojtahedi et al. 2007; Cheng et al. 2010; Sun et al. 2012a, b; Urvashi et al. 2012). In
the here-reported investigation, the enantioselective transformation and potential
enantiomerisation of indoxacarb was elucidated in two soils under non-sterilised
and sterilized conditions using a ChiralCel OD-RH column (CSP: Cellulose tris
(3,5-dimethylphenylcarbamate)) on RP HPLC/MS (Sun et al. 2013). Under
non-sterilised conditions, the degradation of indoxacarb in two soils was markedly
enantioselective. In acidic soil, the half-lives of R-(À)- and S-(+)-indoxacarb were
10 and 14 days, respectively. Acidic soil was preferential to the degradation of R(À)-indoxacarb. In alkaline soil, the half-lives of R-(À)- and S-(+)-indoxacarb were
12 and 5 days, respectively. S-(+)-indoxacarb was preferentially transformed. Under
sterilised conditions, approximately 5–10% of the initial concentration degraded
after 75 days of incubation in acidic soil, whereas in alkaline soil, approximately half
of the initial concentration was transformed mainly due to chemical hydrolysis.
Enantiomerisation was discovered both for acidic and alkaline soils. Thus, the
mutual transformation between two enantiomers must be considered when evaluating environmental fate. The S-(+)-indoxacarb had a significantly higher inversion
rate compared to R-(À)-indoxacarb.
An extended research program on indoxacarb and cis-epoxiconazole
(1-[[(2S,3R)-3-(2-chlorophenyl)-2-(4-fluorophenyl)oxiran-2-yl]methyl]-1,2,4triazole) was performed on Chinese tea types, tea infusions and corresponding soil
samples (Zhang et al. 2014a, b, c). Separation of the analytes was performed on a
chiral stationary phase using high-performance liquid chromatography (RP-HPLC)
with a Lux 3μ Cellulose-1 (Phenomenex, CSP: cellulose tris
(3,5-dimethylphenylcarbamate)) and with tandem quadrupole time-of-flight mass
spectrometry (Q-TOF/MS) detection. For the various teas (green tea, black tea and
pure tea), fresh tea leaf, soil and black tea infusion samples spiked at low, medium
and high levels, average recovery rates for the four enantiomers were found between
61% and 130%. The limits of detection (LODs) for all four target enantiomers were
1.4 μg/kg or below in the different teas and soil samples and even <0.05 μg/kg in the
black tea infusion. The here-developed method was used for real tea sample screening (Zhang et al. 2014a, b, c).
The antiviral agent and pesticide dufulin (IUPAC: diethyl(αRS)-[2-fluoro-α[(4-methyl-1,3-benzothiazol-2-yl)amino]methyl] phosphonate) was investigated
with focus on enantiomer-selective hydrolysis and photochemical transformation
(Zhang et al. 2013a, b). Dufulin is a novel, antiviral agent which is also used as
insecticide (ant-bait) in domestic homes. Furthermore, this compound is widely used
in China to prevent and control viral diseases in tobacco, vegetable and rice. The
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
213