Pesticide Analytical Methodology - American Chemical Society

20 Analysis of Organotin Pesticide Residues by Gas Chromatography/Mass Spectrometry T. E. STEWART and R. D. CANNIZZARO

Downloaded by UNIV LAVAL on October 20, 2015 | http://pubs.acs.org Publication Date: October 30, 1980 | doi: 10.1021/bk-1980-0136.ch020

Thompson-Hayward Chemical Company, Kansas City, KS 66106

Organotin compounds (tetravalent Sn) were found in the 1950's to possess certain fungicidal and biocidal activity.(1) This activity along with the fact that organotins were much less toxic than other organometallics, such as organomercurials or organoarsenicals, established their agricultural importance. Triaryltin compounds such as triphenyltin hydroxide (TPTH, Fentin hydroxide, Du-Ter, I), or triphenyltin acetate (TPTOAC, Brestan, II) have been shown to be effective as protectant fungicides. These compounds have demonstrated other activity such as antifoulants, bactericides and algicides. Due to their low phytotoxicity they have been develop ed for plant protection. In several cases they have been re ported to exhibit the unusual property of deterring insects from feeding. (2) Trialkyltin compounds have been shown to be effective agriculturally. Tributyltin oxide (III) has insecticidal and fungicidal activity, but generally has not been useful for plant protection due to phytotoxicity and volatility prob lems. Tricyclohexyltin hydroxide (TCTH, IV) has been an ex tremely effective acaricide.(3) Developed under the trade name Plictran, this compound was one of the first commercial acaricides. A n o t h e r t r i a l k y l t i n compound u n d e r d e v e l o p m e n t i s hexakis (β ,β - d i m e t h y l p h e n y l e t h y l ) d i s t a n n o x a n e (Vendex, V ) , w h i c h i s a l s o an e f f e c t i v e a c a r i c i d e . The e a r l i e s t methods f o r t h e d e t e r m i n a t i o n o f o r g a n o t i n compounds i n v o l v e a c i d i c d i g e s t i o n o f t h e compound t o i n o r g a n i c t i n , which i s then determined s p e c t r o p h o t o m e t r i c a 1 l y w i t h s e v e r a l s u i t a b l e c o l o r i m e t r i c r e a g e n t s . ( 4 ,_5 ,6 ,]_) These m e t h ods s u f f e r f r o m a l a c k o f s p e c i f i c i t y s i n c e t h e r e may be organotins present w i t h i n the plant. These m e t h o d s a l s o c a n n o t d i s t i n g u i s h among t h e d i f f e r e n t o r g a n o t i n p e s t i c i d e s and a r e v e r y d i f f i c u l t t o p e r f o r m .

0-8412-0581-7/80/47-136-367$05.50/0 © 1980 American Chemical Society

In Pesticide Analytical Methodology; Harvey, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1980.


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R e c e n t m e t h o d o l o g y o v e r c o m e s a number o f t h e s e p r o b l e m s . S e v e r a l methods a r e a v a i l a b l e f o r t h e a n a l y s i s o f t r i c y c l o h e x y l t i n hydroxide.(8,9) T h e s e methods a r e n o t a p p l i c a b l e t o t h e t r i p h e n y l t i n compounds b e c a u s e o f t h e i r t h e r m a l i n s t a b i l i t y . Work by E p o s t o , e t . a l . (10) has shown t h a t TPTH and TCTH can be d e r i v a t i z e d w i t h p h e n y l m a g n e s i u m b r o m i d e (PhMgBr) t o f o r m t h e t e t r a p h e n y l and t r i c y c l o h e x y l p h e n y l d e r i v a t i v e s , r e s p e c t i v e l y , w h i c h can t h e n be q u a n t i t a t e d by GLC. R e c e n t w o r k by S o d e r q u i s t ( 1_1) i n v o l v e s t h e r e d u c t i o n of t h e t r i p h e n y l t i n hydroxide to t r i p h e n y l t i n hydride, which i s then determined by GLC. T h i s method a l s o a l l o w s f o r t h e f o r m a t i o n o f h y d r i d e s o f any m e t a b o l i t e s s u c h as t h e d i p h e n y l t i n d i h y d r i d e , w h i c h may be q u a n t i t a t e d . W r i g h t ( l _ 2 ) has shown t h a t t h e m e t h y l d e r i v a t i v e o f TPTH can be c h r o m a t o g r a p h e d on a c a p i l l a r y c o l u m n and d e t e c t e d w i t h a FP d e t e c t o r . A t Thompson-Hayward, a method has been d e v e l o p e d f o r TPTH t h a t p o s s i b l y may be u s e d f o r a v a r i e t y o f o t h e r o r g a n o t i n p e s t i c i d e s . T h i s method i n v o l v e s the c o n v e r s i o n o f TPTH t o t h e m e t h y l d e r i v a t i v e . The f l o w scheme i s shown i n F i g u r e 1. TPTH i s f i r s t c o n v e r t e d t o t h e t r i p h e n y l t i n c h l o r i d e (TPTC1, V I ) and t h e n t h e c h l o r i d e i s r e a c t e d w i t h m e t h y l m a g n e s i u m c h l o r i d e (CH^MgCl) t o f o r m t h e m e t h y l d e r i v a t i v e , t r i p h e n y l m e t h y l t i n (TPTM, V I I ) . The m e t h y l d e r i v a t i v e can be gas c h r o m a t o g r a p h e d and q u a n t i t a t e d by a mass s p e c t r o m e t e r set to monitor characteristic ions (m/e) of t h e compound ( s e l e c t i v e i o n m o n i toring) . Experimental: All solvents and reagents u s e d i n t h i s method w e r e pesticide quality. M e t h y l m a g n e s i u m c h l o r i d e 2.9M i n THF was o b t a i n e d f r o m A l d r i c h C h e m i c a l Company. T r i p h e n y l t i n h y d r o x i d e and t r i p h e n y l m e t h y l t i n w e r e o b t a i n e d f r o m V e n t r o n . Tric y c l o h e x y I t i n h y d r o x i d e and Vendex were a n a l y t i c a l s t a n d a r d s . T r i p h e n y l e t h y l t i n was s y n t h e s i z e d and c h a r a c t e r i z e d a t Thompson-Hayward C h e m i c a l Company. Gas c h r o m a t o g r a p h i c and mass s p e c t r a l d a t a were c o m p i l e d by a F i n n i g a n 6110 d a t a s y s t e m c o u p l e d t o a F i n n i g a n 4000 mass s p e c t r o m e t e r and 9600 gas c h r o m a t o g r a p h . Some r e s u l t s were o b t a i n e d u s i n g a F i n n i g a n PR0MIM ( P r o g r a m m a b l e M u l t i p l e I o n M o n i t o r i n g ) s y s t e m , c o u p l e d t o a 4-pen s t r i p c h a r t r e c o r d e r and L a b o r a t o r y D a t a C o n t r o l i n t e g r a t o r . M e t h o d s and

Procedures:

P r i o r t o e x t r a c t i o n , s a m p l e s t o be a n a l y z e d a r e g r o u n d or chopped until they are of u n i f o r m consistency. The p r e p a r e d sample i s w e i g h e d i n t o a b l e n d e r ; 150 ml o f s u i t a b l e s o l v e n t i s added and the sample i s b l e n d e d a t a h i g h speed


STEWART

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Pesticide

369

Residues


20.

I

TPTH

Figure 1.

VI

TPTCI

VII

TPTM

Reaction scheme for the conversion of TPTH to TPTM


370

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for 5 m i n u t e s . The extract i s vacuum f i l t e r e d through a B u c h n e r f u n n e l i n t o a f l a t - b o t t o m f l a s k . The f i l t e r c a k e i s a g a i n b l e n d e d and f i l t e r e d . The two e x t r a c t s a r e c o m b i n e d , d r i e d o v e r sodium s u l f a t e and t h e n e v a p o r a t e d t o d r y n e s s on a rotary f l a s h evaporator. Florisil

Column

Clean-up;

The e x t r a c t i s d i s s o l v e d i n 10 ml o f d i c h l o r o m e t h a n e and t r a n s f e r r e d t o a 19 mm i . d . X 300 mm g l a s s chromatographic c o l u m n p a c k e d as f o l l o w s : 15 ml o f 107 d e a c t i v a t e d Florisil (10 ml H 0 + 90 grams F l o r i s i l ) f o l l o w e d by a 2 cm l a y e r o f s o d i u m s u l f a t e w h i c h has been p r e w a s h e d i n o r d e r w i t h 50 ml methanol, 50 ml a c e t o n e , and 50 ml d i c h l o r o m e t h a n e . The sample f l a s k i s r i n s e d t w i c e w i t h a d d i t i o n a l 10 ml and 5 ml portions of d i c h l o r o m e t h a n e , w h i c h are t r a n s f e r r e d to the c o l u m n . When t h e s o l v e n t has r e a c h e d t h e t o p o f t h e sodium sulfate, t h e f l a s k i s r i n s e d w i t h two 15 ml p o r t i o n s of a c e t o n e w h i c h a r e t h e n t r a n s f e r r e d t o t h e c o l u m n . The s o l v e n t i s a l l o w e d t o d r a i n t o the top of the sodium s u l f a t e l a y e r . T h e s e washes a r e d i s c a r d e d . A 200 ml volume o f m e t h a n o l i s added t o t h e c o l u m n t o e l u t e t h e TPTH, w h i c h i s c o l l e c t e d i n a f l a s k . The m e t h a n o l i s e v a p o r a t e d t o d r y n e s s on a r o t a r y f l a s h evaporator. o


?

C o n v e r s i o n o f TPTH t o T P T C l : The c l e a n e d - u p r e s i d u e i s d i s s o l v e d i n 25 ml o f 6N HC1 by s o n i c a t i o n and t h e r e s u l t i n g s o l u t i o n t r a n s f e r r e d t o a separatory funnel. The f l a s k i s t h e n r i n s e d w i t h 50 ml o f d i c h l o r o m e t h a n e which i s l i k e w i s e t r a n s f e r r e d t o the s e p a r a tory funnel. The T P T C l i s p a r t i t i o n e d i n t o t h e d i c h l o r o m e t h a n e , w h i c h i s removed, f i l t e r e d and d r i e d t h r o u g h a pad o f sodium s u l f a t e . The aqueous p h a s e i s e x t r a c t e d a g a i n w i t h an a d d i t i o n a l 50 ml o f d i c h l o r o m e t h a n e . The o r g a n i c phase i s d r i e d over the sodium s u l f a t e , combined w i t h the o r i g i n a l e x t r a c t , and e v a p o r a t e d t o d r y n e s s on a r o t a r y f l a s h e v a p o r a tor . C o n v e r s i o n of TPTCl

t o TPTM:

The TPTCl i s dissolved i n 6 ml o f hexane and 4 ml tetrahydrofuran and r e a c t e d w i t h 2.0 ml o f 2.9M CH^MgCl i n THF f o r one h a l f h o u r a t room t e m p e r a t u r e . E x c e s s CH^MgCl i s deactivated w i t h 50 ml s a t u r a t e d ammonium c h l o r i d e s o l u t i o n and t h e e n t i r e r e a c t i o n m i x t u r e i s t r a n s f e r r e d t o a s e p a r a t o r y


20.

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A N D

CANNizzARO

Organotin

Pesticide

Residues

371

f u n n e l . The f l a s k i s r i n s e d w i t h 50 m l o f hexane w h i c h i s then t r a n s f e r r e d t o the separatory f u n n e l . The TPTM i s e x tracted i n t o hexane, which i s f i l t e r e d t h r o u g h a sodium s u l f a t e p a d i n t o a f l a t - b o t t o m f l a s k . The aqueous p o r t i o n i s e x t r a c t e d w i t h a n a d d i t i o n a l 50 ml o f h e x a n e , t h e hexane i s f i l t e r e d a n d c o m b i n e d w i t h t h e o r i g i n a l e x t r a c t . The h e x a n e e x t r a c t i s e v a p o r a t e d t o d r y n e s s on a r o t a r y f l a s h e v a p o r a tor .


A l u m i n a Column C l e a n - u p : A 19 mm i . d . X 300 m l g l a s s c h r o m a t o g r a p h i c c o l u m n i s p r e p a r e d a s f o l l o w s : 1 cm o f s o d i u m s u l f a t e i s added t o a c l o s e d c o l u m n ; 50 m l o f hexane i s t h e n a d d e d , f o l l o w e d by 21 ml o f 67o d e a c t i v a t e d n e u t r a l a l u m i n a ( 9 4 grams a l u m i n a + 6 grams H 0 ) . A f t e r t h e a l u m i n a s e t t l e s 1 cm o f s o d i u m s u l f a t e i s added a n d t h e h e x a n e i s d r a i n e d t o t h e t o p o f t h e s o d i u m s u l f a t e . The sample c o n t a i n i n g t h e TPTM i s d i s s o l v e d i n 10 m l o f h e x a n e a n d t r a n s f e r r e d t o t h e c o l u m n . The f l a s k i s r i n s e d w i t h an a d d i t i o n a l 5 m l o f hexane w h i c h i s t r a n s f e r r e d t o t h e c o l u m n . The hexane i s a l l o w e d to drain to the top of the s o d i u m s u l f a t e a n d i s d i s c a r d e d . 200 ml o f hexane i s added t o t h e c o l u m n a n d t h e TPTM e l u a t e i s c o l l e c t e d i n a f l a t - b o t t o m flask. ?

GC/MS A n a l y s i s : A sample i s d i l u t e d i n an a p p r o p r i a t e volume o f i n t e r n a l standard stock s o l u t i o n a n d an a l i q u o t o f t h e sample i s i n j e c t e d i n t o a gas chromatograph/mass s p e c t r o m e t e r m o n i t o r i n g m/e 349 a n d 3 5 1 . The peak a r e a s o f t h e TPTM a n d i n t e r n a l s t a n d a r d a r e i n t e g r a t e d a n d e x p r e s s e d a s t h e r a t i o o f TPTM:I n t e r n a l Standard and t h e r a t i o o f those areas r e s p e c t i v e l y are used t o c o n s t r u c t a standard curve. The amount o f TPTM p r e s e n t i s then c a l c u l a t e d from t h e standard curve. Results

and D i s c u s s i o n :

As mentioned p r e v i o u s l y , t h e formation of the methyl d e r i v a t i v e i s s i m i l a r t o s e v e r a l methods t h a t a l r e a d y have been developed f o r o r g a n o t i n p e s t i c i d e s . The u t i l i z a t i o n o f this derivative i n conventional gas chromatographic r e s i d u e p r o c e d u r e s p r e s e n t s many c h a l l e n g e s . E l e c t r o n capture detection i s s e n s i t i v e enough b u t r e q u i r e s extensive clean-up w h i l e w i t h F I D a n d FPD t h e s e n s i t i v i t y i s l o w e r t h a n d e s i r e d . The development o f a r o u t i n e GC/MS p r o c e d u r e ( s i n g l e o r m u l t i p l e i o n m o n i t o r i n g ) was c h o s e n t h e n as t h e o n l y p o s s i b l e alternative. A SIM ( s e l e c t i v e i o n m o n i t o r i n g ) method i s s p e c i f i c f o r r e t e n t i o n t i m e a n d a s w e l l as f o r c h a r a c t e r i s t i c i o n s (m/e).


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The mass s p e c t r u m o f t r i p h e n y l m e t h y l t i n i s presentçd^in |jgure 2 J ^ Q shows t h e prédominent t i n i s o t o p e s , Sn, Sn, and Sn. The v a r i o u s t i n i s o t o p e s a r e l i s t e d i n Table I . 3

I

TABLE I TIN


H2„ 114f U

S n

5

117^" n s f 119^ 1

2

0

S n

1

2

2

S n

124f Sn

ISOTOPE MASSES AND ABUNDANCES

Mass ( 1 3 )

Abundance ( 1 4 ) %

111.90494 113.90296 114.90353 115.90211 116.90306 117.90179 118.90332 119.90213 121.90341 123.90524

0.95 0.65 0.34 14.24 7.57 24.01 8.58 32.27 4.71 5.98

The f r a g m e n t a t i o n p a t t e r n o f TPTM r e v e a l s no p a r e n t m o l e c u l a r i o n , b u t a t i n i s o t o p e c l u s t e r a t m/e 3 4 7 , 3 4 9 , and 351, which corresponds to the t r i p h e n y l t i n moiety. The s p e c t r u m a l s o shows a t i n i s o t o p e c l u s t e r a t m/e 193, 195, and 197 c o r r e s p o n d i n g to the monophenyltin moiety. This f r a g m e n t a t i o n i s s i m i l a r t o t h a t o b s e r v e d by C h a m b e r s ( 1 5 ) . The mass s p e c t r o m e t e r c a n be s e t t o m o n i t o r several characteristic i o n s (m/e) o f t h e t r i p h e n y l m e t h y l t i n derivative. The most l o g i c a l m/e v a l u e s t o be s c a n n e d w o u l d be 347, 349 and 351 b e c a u s e t h e y w o u l d i n d i c a t e t h e p r e s e n c e o f a t r i p h e n y l t i n m o i e t y , w h i l e a l l o w i n g f e w e r i n t e r f e r i n g comp o u n d s . I n t h i s f a s h i o n t h e method d i s t i n g u i s h e s b e t w e e n a t r i p h e n y l t i n compound and any o t h e r o r g a n o t i n p e s t i c i d e . To enhance t h e r e p r o d u c i b i l i t y o f the method, t r i p h e n y l e t h y I t i n (TPTE) i s a d d e d as an i n t e r n a l s t a n d a r d b e f o r e i n j e c t i o n . The TPTE has a s l i g h t l y l o n g e r r e t e n t i o n t i m e on 3% 0V-1 ( a s shown i n F i g u r e 3) and g i v e s a s i m i l a r f r a g m e n t a t i o n p a t t e r n as shown i n F i g u r e 4. A SIM s e r i e s o f TPTM s t a n d a r d s w i t h t h e i n t e r n a l s t a n d a r d TPTE, (TPTE c o n c e n t r a t i o n : 2 0 0 p g / u l ) i s shown i n F i g u r e 5. A s t a n d a r d c u r v e i s c o n s t r u c t e d by p l o t t i n g t h e r a t i o o f t h e peak a r e a s o f TPTM/TPTE v s . t h e amount o f TPTM. A t y p i c a l s t a n d a r d c u r v e i s s h o w n i n F i g u r e 6. The c u r v e i s l i n e a r f r o m 25 pg t o 1 n g o f TPTM. M o s t o f o u r a n l a y s e s a r e c o n d u c t e d i n t h e r a n g e o f 50-400 pg TPTM.


A N D

Organotin

CANNizzARO


STEWART

Figure 2.

Residues

373

Mass spectrum of TPTM

TPTE

TPTM

ι 1 τ I ι ΓΜ ι I M ' I ' I ι I I I ι I

50

Pesticide

100

Scan Number (Time)

150

Figure 3. Reconstructed gas chromato gram of TPTM and TPTE on 3% OV-1 at200°C


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100

10

100

'g

"Ί""Ι-'|'"Ί· 150

100 ο

I

I

10

υ

••lHl-, r 250

3ob" '

350

400

Figure 4. Mass spectrum of TPTE


20.

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Organotin

200 PG TPTM

Pesticide

300 PG TPTM

Residues

375

400 PG TPTM


100 PG TPTM

CANNIZZARO

Figure 5.

SIM chromatograms of TPTM (a) and TPTE (b) (200 pg/pL), ing m/e 347, 349, and 351

monitor-


PESTICIDE

ANALYTICAL

METHODOLOGY


376



20.

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AND

CANNizzARO

Organotin

Pesticide

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377

F i g u r e 7 p r e s e n t s t y p i c a l PROMIM c h r o m a t o g r a m s f r o m t h e a n a l y s i s o f TPTH i n s o y b e a n s . The chromatograms are v e r y c l e a n s h o w i n g none o f t h e i n t e r f e r e n c e s w h i c h n o r m a l l y w o u l d be e n c o u n t e r e d w i t h an EC o r F I d e t e c t o r . A n a l y s e s o f TPTH i n s o y b e a n f o l i a g e , r a d i s h t o p s , b a r l e y and o t h e r c r o p s have v e r y s i m i l a r chromatograms. None o f t h e 63 p e s t i c i d e s r e g i s t e r e d f o r use on s o y b e a n s a r e o b s e r v e d t o i n t e r f e r e w i t h t h e a n a l y s i s . T y p i c a l r e c o v e r y d a t a f o r s o y b e a n s e e d and s o y b e a n f o l i a g e are l i s t e d i n Table I I . I n o u r r e s e a r c h t o i m p r o v e t h e method we have n o t e d t h a t t h e c o n v e r s i o n o f TPTH t o T P T C l i s n o t n e c e s s a r y f o r the d e r i v a t i z a t i o n w i t h CH^MgCl. The c o n v e r s i o n o f TPTH d i r e c t l y t o TPTM has b e e n shown t o be q u a n t i t a t i v e , b a s e d on r e c o v e r y e f f i c i e n c y d a t a and s t u d i e s i n v o l v i n g s t a n d a r d s . T h i s r e a c t i o n scheme i s shown i n F i g u r e 8. Analyses done u s i n g t h i s p r o c e d u r e have v e r y similar r e s u l t s . U s u a l l y w a t e r s a m p l e s t h a t do n o t r e q u i r e e x t e n s i v e c l e a n - u p a r e a n a l y z e d w i t h t h i s method. Other A p p l i c a t i o n s : The a p p l i c a t i o n o f t h i s t y p e o f method t o o t h e r o r g a n o t i n compounds i s a v e r y r e a l p o s s i b i l i t y , as i n d i c a t e d by t h e following investigations: T r i c y c l o h e x y l t i n Hydroxide

(TCTH I V ) :

T r i c y c l o h e x y l t i n h y d r o x i d e was d e r i v a t i z e d by t h e r e a c t i o n scheme i n F i g u r e 9 t o f o r m t h e m e t h y l d e r i v a t i v e , TCTM. The methyl derivative may be d e t e c t e d by m o n i t o r i n g i t s c h a r a c t e r i s t i c i o n s ( m / e ) . The mass s p e c t r u m of TCTM i s shown i n F i g u r e 10. The f r a g m e n t a t i o n shows a t i n i s o t o p e c l u s t e r a t m/e 301 which corresponds t o the d i c y c l o h e x y l m e t h y l t i n m o i e t y . A c o m p a r i s o n o f t h e mass s p e c t r a o f TPTM and TCTM r e v e a l s d i v e r g e n t f r a g m e n t a t i o n pathways. TPTM d i s p l a y s a v e r y i n t e n s e i o n a t m/e 351 (M-15) w h i l e TCTM e x h i b i t s a b a s e peak a t m/e 219 w h i c h c o r r e s p o n d s t o t h e monocyclohexylmethylt i n moiety. TCTM a l s o d i s p l a y s a t i n i s o t o p e c l u s t e r a t m/e 301 w h i c h c o r r e s p o n d s t o t h e d i c y c l o h e x y l m e t h y l t i n m o i e t y . T h i s t i n i s o t o p e c l u s t e r a p p e a r s t o be a p p r o p r i a t e f o r q u a n t i t a t i v e purposes. TPTM and TCTM c a n e a s i l y be s e p a r a t e d on a 3% 0V-7 c o l u m n as shown i n F i g u r e 11. F i g u r e 12 d e m o n s t r a t e s t h a t SIM c h r o m a t o g r a m s o f TPTM and TCTM p r e s e n t no p r o b l e m s i n d i s t i n g u i s h i n g b e t w e e n t h e two d e r i v a t i v e s e v e n when comp l e t e s e p a r a t i o n i s not a c h i e v e d .


378

PESTICIDE

ANALYTICAL

METHODOLOGY

TABLE I I


R e c o v e r y o f T r i p h e n y l t i n H y d r o x i d e From Soybeans and Soybean F o l i a g e

Soybeans L e v e l of

Fortification (ppm) 0.05 0.10 0.20

Number o f T r i a l s

% Recovery Average

34 18 2

76 83 77

Mean = 78.3 S t a n d a r d Dev. = 11.43

Soybean

Foliage

Level of

Fortification (ppm)

0.05 0. 10 0.50 1.00 25.00 50.00 100.00

Number o f T r i a l s

% Recovery Average

5 5 15 2 7 1 2

96 98 82 68 86 81 76

Mean = 84.5 S t a n d a r d Dev. = 18.6


STEWART

A N D

CANNizzARO

Organotin

A


a

Pesticide

Residues

Β

b

a

379

C

b

a

b

TIME Figure 7. Typical PROM1M chromatograms of TPTM (a) and TPTE (b) in soybean extracts: (A) soybean control sample (10 mg sample aliquot injected, < 0.05 ppm); (B) soybean control sample fortified with 0.05 ppm TPTH (10 mg sample aliquot injected, 0.045 ppm found, 90% recovery); (C) soybeans treated at 0.5 lb a.i./acre (10 mg sample aliquot injected, < 0.05 ppm)

I

Figure 8.

TPTH

VII

TPTM

Alternate reaction scheme for the conversion of TPTH to TPTM


380

PESTICIDE

/

\

|^


\^_H"-

IV

Figure 9.

CHaMgCI

OH

Wf

*

ANALYTICAL

/

M E T H O D O L O G Y

\

350 X 3

o

9

ο

9

Q i

25G

Ill

20Q

15(3

3 0 b 3 5 6 ' Figure 13.

9

i „

- ,

6

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Pesticide Analytical Methodology - American Chemical Society

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