Synthetic Pyrethroids: Residue Methodology and Applications

19 Synthetic Pyrethroids: Residue Methodology and

Downloaded by CALIFORNIA INST OF TECHNOLOGY on September 14, 2017 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0042.ch019

Applications

1

D. A. GEORGE, J. E. HALFHILL, and L. M. McDONOUGH Yakima Agricultural Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Yakima, Wash. 98902

The shortcomings of DDT [ l , l , l - t r i c h l o r o - 2 , 2 - b i s = (p-chlorophenyl )ethane] and other chlorinated hydrocarbons has stimulated research into the development of other broad spectrum insecticides that could provide high insecticidal activity combined with low mammalian toxicity and moderate persistence. Compounds related to natural pyrethrum (synthetic pyrethroids) have been developed in recent years that show promise of meeting these requirements. Natural pyrethrum (Fig. 1) i s an ester with synthetic variations of both the acid and alcohol portion of the molecule providing promising insecticides. Field studies indicate that Bioethanomethrin® [(5-benzyl3-furyl)methyl trans-(+)-3-(cyclopentylidenemethyl)-2,2dimethylcyclopropanecarboxylate] and FMC 33297 [m-phenoxybenzyl cis,trans-(±)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane= carboxylate] (Fig. 2), showed promise of controlling insects of certain vegetable crops. Consequently, we investigated methods of detecting their residues. We report here a direct method u t i l i z i n g gas chromatography and electron capture detection for FMC 33297. In addition, we developed a method based on derivatives of the alcohol and acid moieties of the saponified pyrethroid molecule for both pyrethroids (1). This latter method should work equally well with other synthetic pyrethroids (Fig. 3). The sample i s saponified, the alcohol moiety i s extracted with methylene chloride, the water portion i s then a c i d i f i e d , and the acid moiety i s extracted with methylene chloride. Trichloroacetyl chloride with pyridine i s used to form a trichloroacetate ester from the alcohol and trichloroethanol 1/ This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation for use by the U.S. Department of Agriculture nor does i t imply registration under FIFRA as amended.

201

Elliott; Synthetic Pyrethroids ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

SYNTHETIC

202

CHRY3ANTHEMATE3

PYRETHROIDS

PYRETHRATES


3 PYRETHRIN I

Ο

PYRETHRIN Π

8

CINERIN I

CINERIN Π

JASMOLIN 1

JASMOLIN

Figure 1.

Π

Natural pyrethrums: chrysanthemates and pyrethrates

Figure 2. Synthetic pyrethroids Bioethanometrin and FMC 33297


19.

GEORGE

with

pyridine

ester

with

increases

with

The the

the

derivatized both

at

8 microns,

a

capture

products

5.68

used

to

form

compound

t h e nanogram gas

an

in

the

range

chromatograph

detector.

support at

to

by a

the

( F i g . 4).

is

pyrethroids,

is

trichloro

sensitivity

spectra

frequency

of

use of

are determined

an electron

infrared

vibrational


This

the derivatives

equipped

203

and dicyclohexylcarbodiimide

the acid.

derivatives when

Residue Methodology

E T A L .

expected

microns

the aromatic

structures

The carbonyl ether

and the carbon-chloride

for the

trichloroacetate

stretching

bands

for

stretching frequency

are near

14

is

a n d 17

microns. The the

esters

carbonyl

C-O-C the

from

the acid

stretching

t r i p l e t

at

8.7,

carbon-chloride

moiety

frequency

8.9,

and 9.1

stretching

for both

at

5.78

pyrethroids

microns,

microns

a

( F i g . 5).

frequencies

are at

show

strong Again,

14

a n d 18

microns. The

high

structures ion

was f o u n d

331.9773). was base from was

be m/e

The molecular

324.0445

peak

of

the trichloroacetate

corresponding

the molecule. at

m/e

to

of

2

The

ester

peak

of

of

the trichloroethanol

(calculated

m/e

337.9200)

ester,

i o n from

the

loss

of

2

in

atoms

electron

ion ester

of

a method

in

greater

detector;

of

5 to

50

sensitivity

of

the

m/e

183.0808.

corresponding

for determining was u s e d .

t h e compound

the result nanograms. with

at

peak of

to

163.0058.

molecule

make

the loss

The

was m / e

The base

to

was f o u n d

m/e

derivative

derivative

ester,

was d e v e l o p e d

the complete

the molecule

capture

at

ester

345.9765).

is

a

residues

The 2

sensitive

standard

However,

we

to

curve

obtained

the derivatization

method.

Studies emulsifiable

lentils

as

oz/acre)

a 14

collected were

concentrate

spray

2 times

a n d 21 after

h r , and a f t e r

samples

The

m/e

the loss

m/e

ester

the molecule,

was f o u n d

3

which

sensitivity

10-fold

168

2

addition,

chlorine

(10

of

C0 CH CC1 ,

FMC 3 3 2 9 7

were

to

( F i g . 7).


An

at

the trichloroacetate

corresponding

peak

to

ester

324.0449).

was f o u n d

(calculated

base

Residue

m/e

corresponding

The

a

m/e


trichloroacetate

a

(calculated


the loss

346.9764

trichloroacetate

with

molecular

Bioethanomethrin

ion for the trichloroacetate

was m / e

ion of

337.9185

the

expected

The

2

molecular

molecular

In

the

(C0 CH CCl3).

2

FMC 33297

of

the

(calculated

The base

149.1323,

confirm ( F i g . 6).

331.9789

ion of

be m/e

found

the

to

ester

to

C H 0 Cl3 2

spectra formed

found

171.0804,

of

mass

the derivatives

for the trichloroacetate

derivative

3

resolution

of

the

selected

days

the

at

of

before

first

of

harvest.

spray

2nd t r e a t m e n t randomly

Bioethanomethrin

the rate at at

0 h r ,

700

g

Foliage 66

applied

residues

h r , and

0 h r a n d 72

throughout

was

Ai/hectare

the plot,

hr.

The

placed


204

SYNTHETIC

2 R CH -O-C-CCl.

c i c-coci

2

R -CH 0H o

1"1)\ OH , MeOH / U-ΛΙΙ / - --^ 2) H,0 \

Q

R -C-O-CH^R

λv

Λ

Ζ

+

+

PYRETHROIDS

Ô

0

C-CH OH

c

ι R -COOH

R -C-0-CH -Cl 2

pyridine - DCC


Figure 3.

Derivative step (DCC is dicyclohexylcarbodiomide)

WAVENUMBfl (CM>

0.00

—

Ί IΓ T

.1 ο

11

.20

II

S

f

w

f

30

— 1

.40 .5 0 60 .70 1.00 25

30

40

3000

2.5 3.0

5.0

60

2000

4.0

5

0

70

β ϋ

1300

6.0

7

ΙΟ 0

l? 0

4

0

1000 8 0 0

0

80

10.0 12 0

ιβ 0

600

14

0

WAVELENGTH (MICRONS)

Figure 4.

6Ο

Infrared spectra of trichloroacetate ester derivatives


16 0

18

0

3

19.

GEORGE

in

plastic

samples

bags,

were

subsamples 200 The

foliage to

extract

liquid

of

Baker s

through The

in

lentils

and

the residue

The

acetonitrile

as

compare were

168-hr by

hexane

were

Table

to

0.6

Table

in

50 m l o f

analyzed.

between

foliage

time.

determined of

loss

Immediately Control

Recoveries

the harvest

Residues

between

sampling

was

with

in

g

1.5%

was t h e

and

same

to

dryness,

acetonitrile.

t h e same

from

after to

was

manner

zero

of

samples

after

No

1.0

residue ppm)

and

residues

foliage of

700

at g

oz/acre).

found

(ppm)±/

Trichloroethanol ester derivative

1

0.350

0.447

.035

.066

168

.000

.000

Treatment

2

0

.647

.689

72

.000

.000

corrected

the no

to

66

were

residues

derivative

on l e n t i l

derivative

0

0.1

an a p p l i c a t i o n

ester

(hr)

of

ester

Trichloroacetate

and

sampling

the

showed

derivative.

Bioethanomethrin (10

derivatives

by t h e end o f

( i n the range ester

the 2

the 7-day

spraying,

o r check

Treatment

Results

(20

passed

and the residue

during

Residues

treatment

subjecting

l e n t i l s .

intervals

Ai/hectare

1/

hexane

and chromatographed

ppm a n d d e c l i n e d

various

Interval

methylene

column

hexane

Extraction

84.2% f o r t h e t r i c h l o r o a c e t a t e

I.

oxide

was e v a p o r a t e d

was e v a p o r a t e d

for the trichloroethanol in

analyzed.

the

and then

was e l u t e d

the extract

The r a t e I.

method.

found

anhydrous until

hexane,

g

sample.

sampling

averaged 80.3%

solution

in

either

through

an aluminum

After

also Then

favorably.

0.4

with

in

Bioethanomethrin

were

residues

shown

with

up by e v a p o r a t i n g

was p a r t i t i o n e d

the foliage The

is

in

50

2 minutes

was r e f r i g e r a t e d

the residue

frozen

hexane.

for the foliage.

redissolved

The

thoroughly;

blended

and f i l t e r e d

0536).

the column,

and mixed

for analysis,

chromatography

acetonitrile

the laboratory.

was c l e a n e d

Analyzed

T

at

chopper

The f i l t r a t e

redissolving

it

a

chloride,

sulfate.

chloride,


removed

ml methylene

sodium

as

and frozen

put through

were

205

Residue Methodology

E T A L .

to

100% b a s e d

on

recoveries.


206

SYNTHETIC

PYRETHROIDS

WAVENUMSER (CM"') 0.00 J

ο

11

.20

Κv Λ if 1 Λι II >

rw

1


30 .40 .5 0 .60 .70 1.00

CO CD
.0 12.0 14.0 16.0 18.0

(MICRONS)

Infrared spectra of trichloroethyl derivatives

lOOi 80 60 >I-

40

LA

Synthetic Pyrethroids: Residue Methodology and Applications

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