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Determination of dibenzo-p-dioxin (DBD) and dibenzofuran (DBF) in paper pulp mill defoamer additives and in paper pulp samples
C h e m o s p h e r e , Vol.20, N o s . l O - 1 2 , P r i n t e d in Great B r i t a i n
pp 1611-1618,
1990
0 0 4 5 - 6 5 3 5 / 9 0 $3.00 + .O0 P e r g a m o n Press DIc
D E T E R M I N A T I O N OF D I B E N Z O - p - D I O X I N (DBD) AND D I B E N Z O F U R A N (DBF) IN PAPER PULP M I L L D E F O A M E R A D D I T I V E S AND IN PAPER PULP SAMPLES
G. F. VANNESS,
T. O. TIERNAN*, M. S. HANES, C. J. REYNOLDS, D. J. WAGEL, and J. G. SOLCH
J. H. GARRETT,
D e p a r t m e n t of C h e m i s t r y and Toxic C o n t a i n m e n t R e s e a r c h P r o g r a m W r i g h t State U n i v e r s i t y , Dayton, Ohio, 45435, U.S.A.
ABSTRACT An a n a l y t i c a l p r o c e d u r e has b e e n d e v e l o p e d for q u a n t i t a t i v e l y m e a s u r i n g d i b e n z o - p - d i o x i n (DBD) and d i b e n z o f u r a n (DBF) p r e s e n t at p a r t - p e r - b i l l i o n l e v e l s in p a p e r m i l l d e f o a m e r s a n d p a p e r p u l p u s i n g g a s c h r o m a t o g r a p h y c o u p l e d w i t h e i t h e r low r e s o l u t i o n m a s s s p e c t r o m e t r y ( G C - L R M S ) or h i g h r e s o l u t i o n mass s p e c t r o m e t r y (GC-HRMS). KEYWORDS Dibenzodioxin, dibenzofuran, p r e c u r s o r s of P C D D / P C D F
analysis,
paper
pulp,
defoamer
formulations,
INTRODUCTION In 1987, the U. S, EPA r e l e a s e d a r e p o r t "The N a t i o n a l D i o x i n Study" w h i c h i d e n t i f i e d a p r e v i o u s l y u n s u s p e c t e d s o u r c e of 2 , 3 , 7 , 8 - T C D D c o n t a m i n a t i o n in some areas of the U.S., s p e c i f i c a l l y c e r t a i n types of p u l p and p a p e r m i l l s (i). This led to a more e x t e n s i v e a s s e s s m e n t of s e v e r a l p a p e r m i l l s (the Five Mill Study) w h i c h r e s u l t e d in the f i n d i n g of trace a m o u n t s of 2 , 3 , 7 , 8 T C D D and 2 , 3 , 7 , 8 - T C D F in b l e a c h e d p a p e r pulp, sludges, and e f f l u e n t s (2). Further investigation indicated that defoamer additives u s e d in p u l p manufacturing m i g h t s e r v e as s o u r c e s of d i b e n z o - p - d i o x i n (DBD) and d i b e n z o f u r a n (DBF) that could u n d e r g o c h l o r i n a t i o n to y i e l d T C D D and TCDF. P r e l i m i n a r y m e a s u r e m e n t s of the c o n c e n t r a t i o n of DBF in d e f o a m e r a d d i t i v e s s h o w e d levels w h i c h were h i g h e r than e x p e c t e d ( p a r t s - p e r - m i l l i o n ) , a l t h o u g h the p r e s e n c e of DBD was not c o n f i r m e d (3) . The p r e s e n t paper d e s c r i b e s a n a l y t i c a l p r o c e d u r e s r e c e n t l y d e v e l o p e d and i m p l e m e n t e d in our l a b o r a t o r y to d e t e r m i n e DBD and DBF levels in v a r i o u s d e f o a m e r f o r m u l a t i o n s and p u l p w h i c h may u n d e r g o c h l o r i n a t i o n in the course of p u l p m a n u f a c t u r i n g . The o b j e c t i v e of this work was to d e v e l o p more d e f i n i t i v e a n a l y t i c a l p r o c e d u r e s w h i c h w o u l d m i n i m i z e s a m p l e p r e p a r a t i o n p r i o r to GC-MS a n a l y s i s and w h i c h w o u l d a c h i e v e d e t e c t i o n limits of less than one p a r t - p e r - b i l l i o n . It was a l s o of i n t e r e s t to c o m p a r e analytical data obtained using GC-low r e s o l u t i o n mass s p e c t r o m e t r y (GC-LRMS) w i t h c o r r e s p o n d i n g d a t a o b t a i n e d u s i n g G C - h i g h r e s o l u t i o n mass s p e c t r o m e t r y (GC-HRMS). EXPERIMENTAL
PROCEDURES
A v a r i e t y of d e f o a m e r f o r m u l a t i o n s and paper p u l p s a m p l e s w e r e i n v e s t i g a t e d in this s t u d y in an e f f o r t to e s t i m a t e the range of c o n c e n t r a t i o n s of DBD and DBF p r e s e n t in such m a t e r i a l s . The c o m p o s i t i o n of m o s t of the c h e m i c a l d e f o a m e r f o r m u l a t i o n s t e s t e d h e r e had not b e e n d i s c l o s e d to our laboratory.
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H o w e v e r , it w a s p o s s i b l e to g r o u p t h e s e d e f o a m e r formulations into two categories, oil-based and emulsified formulations, based upon visual i n s p e c t i o n of the m a t e r i a l s and s o l u b i l i t y tests w i t h h e x a n e and water. F i g u r e 1 i l l u s t r a t e s s c h e m a t i c a l l y the s a m p l e p r e p a r a t i o n and a n a l y s i s
0~i~, [~efoamer s, and
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F i g u r e I. Schematic Diagram Showing Preparation Procedures Used in D e t e r m i n a t i o n of DBD and DBF in D e f o a m e r F o r m u l a t i o n s and Pulp s c h e m e d e v e l o p e d and u t i l i z e d in the p r e s e n t study. The oil s a m p l e s were p r e p a r e d u s i n g an a l u m i n a c o l u m n c l e a n u p . The emulsified formulation s a m p l e s and p a p e r p u l p s a m p l e s were p r e p a r e d u s i n g a steam d i s t i l l a t i o n p r o c e d u r e (4) f o l ~ o w e d by an a l u m i n a c o l u m n cleanup. F u l l y d e u t e r a t e d DBD and DBF were added to t h e s a m p l e s as i n t e r n a l standards prior to extraction. The s a m p l e e x t r a c t s w e r e a n a l y z e d by e i t h e r h i g h r e s o l u t i o n gas c h r o m a t o g r a p h y - low r e s o l u t i o n mass s p e c t r o m e t r y (HRGC-LRMS) or h i g h r e s o l u t i o n gas c h r o m a t o g r a p h y - high r e s o l u t i o n mass s p e c t r o m e t r y (HRGCHRMS). For p u r p o s e s of comparison, some d e f o a m e r s o l u t i o n s were a n a l y z e d d i r e c t l y by H R G C - H R M S , w i t h o u t prior c l e a n u p or s e p a r a t i o n , However, there are two s i g n i f i c a n t p r o b l e m s w i t h the d i r e c t analysis. First, if the sample is quite viscous, d i l u t i o n may be n e c e s s a r y for p r o p e r i n j e c t i o n into the gas c h r o m a t o g r a p h . A large d i l u t i o n a f f e c t s the d e t e c t i o n limit that can be achieved. Secondly, the p r e s e n c e of low levels of DBF in m a n y of the s o l v e n t s w h i c h can be used for d i l u t i o n of the s a m p l e p r e c l u d e s r e l i a b l e q u a n t i t a t i o n of the DBF in d e f o a m e r s that c o n t a i n low p a r t per b i l l i o n levels of this compound. S p e c i f i c d e t a i l s of the a n a l y t i c a l p r o c e d u r e s are p r e s e n t e d in the following.
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Sample
Preparation
i. Steam Distillation: Prewash the steam distillation apparatus (SDA), a n d c o n d e n s e r for a p e r i o d of one h o u r w i t h m e t h y l e n e c h l o r i d e , t h e n discard this solvent. P l a c e an a p p r o p r i a t e q u a n t i t y ( 2 5 0 - 5 0 0 mL) of h i g h purity water (HPLC G r a d e or e q u i v a l e n t ) i n t o the S D A flask, a n d add dsdibenzo-p-dioxin and ds-dibenzofuran to the f l a s k . A s s e m b l e the c o m p o n e n t s of the SDA, a d d i n g 10 m L of h i g h p u r i t y w a t e r a n d 10 m L of h e x a n e to the e x t r a c t o r of the SDA. O p e r a t e the a s s e m b l e d SDA for a p e r i o d of one hour, t h e n r e m o v e the o r g a n i c a n d a q u e o u s l i q u i d s f r o m the e x t r a c t i o n section u s i n g s e v e r a l h e x a n e r i n s e s a n d r e t a i n this s a m p l e for a n a l y s i s as a s y s t e m blank. E x t r a c t the a q u e o u s p h a s e w i t h h e x a n e to o b t a i n a f i n a l e x t r a c t for analysis. W a s h the e n t i r e S D A w i t h m e t h y l e n e c h l o r i d e as a f i n a l c l e a n i n g p r o c e d u r e . T r a n s f e r an a l i q u o t of the s a m p l e to the S D A flask, add dsdibenzo-p-dioxin and ds-dibenzofuran, a n d the a p p r o p r i a t e a m o u n t of h i g h p u r i t y w a t e r ( 2 5 0 - 5 0 0 mL). A t t a c h the S D A e x t r a c t o r to the flask, p l a c e I0 m L of h i g h p u r i t y w a t e r a n d h e x a n e i n t o the S D A e x t r a c t o r , and attach the c o n d e n s e r . E x t r a c t the s a m p l e for t h r e e h o u r s . R e p e a t the t r a n s f e r steps outlined above. C o n c e n t r a t e the f i n a l s a m p l e e x t r a c t to a v o l u m e of 5 m L in p r e p a r a t i o n for a l u m i n a c o l u m n c l e a n u p , or if the s a m p l e e x t r a c t is to be a n a l y z e d w i t h o u t f u r t h e r c l e a n u p , c o n t i n u e c o n c e n t r a t i n g to a v o l u m e of 90 pL. 2. Alumina Column Chromatoqraphy: For a s a m p l e w h i c h h a s n o t b e e n subjected to s t e a m d i s t i l l a t i o n , w e i g h an a l i q u o t of the s a m p l e into a s c r e w c a p vial. Add d.-dibenzo-p-dioxin and d s - d i b e n z o f u r a n standards, f o l l o w e d b y 2 m L of 5% (v/v) t o l u e n e in h e x a n e . T h o r o u g h l y m i x the s a m p l e and solvent. Chromatograph t h i s m i x t u r e on a c o l u m n c o n t a i n i n g I0 g of basic alumina ( a c t i v a t e d at 6 0 0 ° C ) , e l u t i n g the c o l u m n s e q u e n t i a l l y w i t h 30 m L of h e x a n e , 50 mL of 8% m e t h y l e n e c h l o r i d e in h e x a n e , a n d 45 m L of m e t h y l e n e c h l o r i d e , r e t a i n i n g o n l y the last e l u a t e f r a c t i o n . A d d 1 mL of t o l u e n e to the r e t a i n e d e l u a t e a n d c o n c e n t r a t e to a v o l u m e of 90 ~L at r o o m temperature, using a N-Evap concentrator. A d d i0 ~L of d 1 0 - p h e n a n t h r e n e to the c o n c e n t r a t e d e x t r a c t , a n d a n a l y z e the e x t r a c t by e i t h e r HRGC-HRMS or H R G C - L R M S . Extracts of s a m p l e s which have been previously steam distilled, as d e s c r i b e d above, are transferred directly to t h e a l u m i n a column and chromatographed just as d e s c r i b e d in the f o r e g o i n g p r o c e d u r e . 3. Direct Injection Technique: For s a m p l e s w h i c h are to be a n a l y z e d b y direct injection i n t o the G C - M S , w e i g h an a l i q u o t of the s a m p l e i n t o a vial, t h e n a d d 1 0 0 0 n g of the d . - D B D a n d d s - D B F i n t e r n a l s t a n d a r d s . Inject a p o r t i o n of this s a m p l e i n t o the H R G C - H R M S . If the s a m p l e is too v i s c o u s for direct injection, dilute it w i t h t o l u e n e initially, then add the d e u t e r a t e d i n t e r n a l s t a n d a r d s , a n d a n a l y z e the s a m p l e b y H R G C - H R M S . High
Resolution
Gas
Chromatography-Mass
Spectrometry
(HRGC-MS)
The HRGC-LRMS analyses for which results are presented herein were accomplished using a Hewlett-Packard 5980A Gas Chromatograph directly c o u p l e d to an E x t r e l E L Q - 4 0 0 Q u a d r u p o l e M a s s S p e c t r o m e t e r , o p e r a t e d in the selected ion monitoring mode. T h e c a p i l l a r y c o l u m n u s e d w a s a 60 m D B - 5 c o l u m n , 0 . 3 2 m m I.D., w i t h a f i l m t h i c k n e s s of 1.0 ~m, o p e r a t e d at 15 psi h e a d p r e s s u r e of h e l i u m . The analyte was injected by splitless injection (split at 45 s e c o n d s ) i n t o the c o l u m n w h i c h was m a i n t a i n e d at a t e m p e r a t u r e of 60°C. F o l l o w i n g i n j e c t i o n , the c o l u m n w a s h e l d at 6 0 ° C for 1 m i n u t e a n d t h e n the t e m p e r a t u r e w a s i n c r e a s e d at a r a t e of 1 5 ° C / m i n u t e to 180°C. The c o l u m n t e m p e r a t u r e w a s t h e n f u r t h e r i n c r e a s e d at a r a t e of 5 ° C / m i n u t e to a
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final t e m p e r a t u r e of 300°C, w h i c h was m a i n t a i n e d for I0 minutes. The mass s p e c t r o m e t e r was o p e r a t e d in the e l e c t r o n impact i o n i z a t i o n m o d e w i t h a s o u r c e t e m p e r a t u r e of 250°C. The ions m o n i t o r e d as i n d i c a t o r s of DBF were m/z 168 and m/z 139, w h i l e those m o n i t o r e d for the i n t e r n a l s t a n d a r d (dsDBF) were m/z 176 and m/z 146. The c o r r e s p o n d i n g ions m o n i t o r e d for DBD w e r e m/z 184 and m/z 128, and m/z 192 and m/z 136 for ds-DBD. The ion m o n i t o r e d as an i n d i c a t o r of the e x t e r n a l standard, d 1 0 - p h e n a n t h r e n e , was m/z 188. The H R G C - H R M S a n a l y s e s were a c c o m p l i s h e d u s i n g a C a r l o - E r b a M e g a 5000 Gas C h r o m a t o g r a p h c o u p l e d via jet s e p a r a t o r to a Kratos M S - 2 5 Mass S p e c t r o m e t e r e q u i p p e d w i t h a D S - 9 0 E Data System. The mass s p e c t r o m e t e r was o p e r a t e d in the s e l e c t e d ion m o n i t o r i n g mode. The c a p i l l a r y GC c o l u m n u s e d was a 30 m DB-5, 0.25 mm I.D. w i t h a film t h i c k n e s s of 1.0 Dm o p e r a t e d at 30 psi h e a d p r e s s u r e of hydrogen. The a n a l y t e was i n j e c t e d by s p l i t l e s s i n j e c t i o n onto the c o l u m n w h i l e the c o l u m n t e m p e r a t u r e w a s m a i n t a i n e d at 6 0 ° C . This t e m p e r a t u r e was m a i n t a i n e d for one m i n u t e f o l l o w i n g injection. The c o l u m n t e m p e r a t u r e was then i n c r e a s e d at 2 0 ° C / m i n u t e to a final t e m p e r a t u r e of 200°C, and h e l d at that t e m p e r a t u r e for 10 minutes. The mass s p e c t r o m e t e r was operated in the e l e c t r o n i m p a c t i o n i z a t i o n mode, with a source t e m p e r a t u r e of 300°C, a n d the a c c e l e r a t i n g v o l t a g e at 4 kV. The ions m o n i t o r e d as i n d i c a t o r s of the v a r i o u s c o m p o u n d s to be s e l e c t e d were: DBF, m/z 168 and m/z 169; ds-DBF, m/z 176; DBD, m/z 184 and m/z 185; and dg-DBD, m/z 192. The ion m o n i t o r e d for the e x t e r n a l standard, d, 0 - p h e n a n t h r e n e , was m/z 188. RESULTS R e s u l t s of a n a l y s e s of oil d e f o a m e r s a m p l e s p r e p a r e d b y a l u m i n a c o l u m n c h r o m a t o g r a p h y and a n a l y z e d by H R G C - H R M S are shown in T a b l e i. Sample c o n c e n t r a t i o n levels r a n g e d from none detected, w i t h d e t e c t i o n limits in the range from 1.2-64 ppb of DBD and 25 ppb - ii ppm of DBF. Average internal standard recoveries achieved for d.-DBD and ds-DBF in t h e s e a n a l y s e s w e r e 56 a n d 74 p e r c e n t , respectively, indicating that the a n a l y t i c a l m e t h o d o l o g y a p p l i e d is q u i t e acceptable. Table
i. D i b e n z o - p - d i o x i n and D i b e n z o f u r a n C o n c e n t r a t i o n s in D e f o a m e r Oils U s i n g A l u m i n a C o l u m n C l e a n u p and A n a l y s i s by H R G C - L R M S
Sample No. N7 N8 N9 NI0 NIl NI2 E1 E2 E3 E4 Lab Blank
Dibenzo-p-dioxin Conc. (ng/g) % Recovery a i0 ND(I.4) 4.9 4.9 5.0 ND(I.4) 2.4 64 i0 6.0 ND(I.2)
a d. - d i b e n z o - p - d i o x i n b ds - d i b e n z o f u r a n
62 50 74 71 71 83 25 41 61 63 18
Dibenzofuran Conc. (ng/g) % R e c o v e r y b 2400 25 93 55 20 25 32 Iii00 318 102 ND(0.03)
60 50 71 68 85 87 88 29 108 65 105
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TIC 227530 m/z 168 TIC 35218 m/z 169
TIC 421284 m/z 176
I
I
I
I
I
I
I
I
600 610 620 680 640 650 660 R.T. 7:46 7:54 8:02 8:09 8:17 8:25 8:83 Figure 2. Selected Ion Chromatogram Obtained by a Kratos MS26, DS-90E Mass Spectrometer for Sample No. X2
TIC 2361 A m~/z 1 ~ Ah
TIci49
/
TIC 229700 m/z 192 /
~
~
,-~
\
~.
I
I
I
I
I
I
I
I
R.T.
680 8:48
690 8:56
700 9:03
710 9:11
720 9:19
780 9:27
740 9:35
Figure 3. Selected Ion Chromatogram Obtained by a Kratos M825, DS-90E Mass Spectrometer for Sample No. X2
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TIC 5568 m/z 146 TIC 15616 m/z 176
TIC 454 m/z 139 TIC 1006 m/z 168
I
I
I
R.T. 19:00
I
I
19:20
I
I
19:40
20:00
Figure 4. Selected Ion Chromatogram Obtained by an ELQ-400 Quadrupole Mass Spectrometer for Sample No, N8
TIC 3296 m/z 136 TIC 7456 m/z 192
Tic 85
m/z 184
I R.T. 20:00
I
I
-
I
--I
20:20 20:40 Figure 5, Selected Ion Chromatogram Obtained by an Extrel ELQ-400 Quadrupole Mass Spectrometer for Sample No. N8
l 21:00
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T h e r e s u l t s o b t a i n e d for three paper pulp samples prepared by steam distillation followed by alumina column chromatography a r e s h o w n in T a b l e 2. As c a n be seen, n e i t h e r D B D n o r D B F w a s d e t e c t e d at a c o n c e n t r a t i o n in e x c e s s of the d e t e c t i o n l i m i t s .
T a b l e 2. Dibenzo-p-dioxin and Dibenzofuran Concentrations in P a p e r P u l p S a m p l e s U s i n g S t e a m D i s t i l l a t i o n F o l l o w e d by Alumina Column Cleanup and Analysis by HRGC-LRMS Dibenzo-p-dioxin Conc. (ng/g) % Recovery a
Sample No.
A5 A9 AI5 Lab Blank Lab blank
ND(3.7) ND(4.3) ND(4.0) ND(2.2) ND(2.6)
Dibenzofuran C_onc.(nq/g_) % Recovery b
52 40 41 29 31
ND(2.3) ND(I.8) ND(I.2) ND(I.4) ND(I.7)
52 41 40 30 33
s ds - d i b e n z o - p - d i o x i n b d8 - d i b e n z o f u r a n In o t h e r s t u d i e s , a set of f i v e d e f o a m e r samples were prepared and analyzed by three different quantitation techniques. In t h e s e tests, two o i l - b a s e d d e f o a m e r s a m p l e s w e r e p r e p a r e d in d u p l i c a t e , u s i n g a l u m i n a c o l u m n
Table 3.
WSU Sample No.
Comparisons of Data Obtained From Analyses of Defoamer Samples Using Different Analytical Procedures
Sample Matrix
HRGC-LRMS Results b
HRGC-HRMS Results a,b
Direct Injection HRGC-HRMS Results a,c
Dibenzofuran Xl X2 X3 X4 X5
Oil Oil Emulsion Emulsion Emulsion
3100 238 4100 723 8.1
2400 405 3402 802 11.3
Mean of Three Data Sets
Standard Deviation
(DBF)_
3059 684 4544 719 12
2853 442 4015 748 10.5
393 225 576 46.8 1.7
Dibenzo-p-Dioxin (DBD) Xl X2 X3 X4 X5 a.
b. c.
Oil Oil Emulsion Emulsion Emulsion
155 ND(6.4) 209 24.9 ND(0.13)
178 10.2 189 26.6 0.81
230 35.7 356 37.8 4.5
188 23.0 251 29.8 2.7
38.4 12.8 74.5 5.7 1.9
Mass resolution was 6000. Samples were extracted and the extracts were subjected to a full clean-up procedure, as described in the paper. Samples were diluted and injected directly into GC-MS, with no prior extraction or cleanup.
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chromatography, as a l r e a d y d e s c r i b e d , a n d the e x t r a c t s were analyzed s e p a r a t e l y by b o t h H R G C - H R M S and H R G C - L R M S . Three emulsified defoamer formulations were also p r e p a r e d in duplicate, using steam distillation, f o l l o w e d by a l u m i n a column chromatography, as d e s c r i b e d above, and these extracts were a n a l y z e d s e p a r a t e l y by both H R G C - L R M S and HRGC-HRMS. A third p o r t i o n of each of the five samples was p r e p a r e d by d i l u t i n g each sample d i r e c t l y with solvent, adding ds-DBD and d.-DBF internal standards, and d i r e c t l y a n a l y z i n g the d i l u t e d aliquots by HRGC-HRMS. The data o b t a i n e d from these several analyses are shown in Table 3. Typical s e l e c t e d - i o n mass c h r o m a t o g r a m s for DBF and DBD, which were o b t a i n e d in the analyses of Sample No. X2 by HRGC-HRMS, are shown in Figures 2 and 3, respectively. Corresponding mass c h r o m a t o g r a m s obtained in the H R G C - L R M S analyses of Sample No. N8 are shown in Figures 4 and 5. The set of ions m o n i t o r e d in the HRMS a n a l y s e s d i f f e r e d from those m o n i t o r e d in the LRMS analyses owing to the low signal r e s p o n s e s at m/z 169 for DBF, and at m/z 185 for DBD, w i t h the LRMS. Also, a s e c o n d a r y ion w a s m o n i t o r e d for each internal s t a n d a r d with the LRMS to p r o v i d e additional confirmation. CONCLUSIONS The data p r e s e n t e d h e r e i n indicate that for the samples a n a l y z e d in this study, the r e s u l t s for D B D and DBF o b t a i n e d by using HRGC-LRMS are c o m p a r a b l e to those o b t a i n e d by using HRGC-HRMS. The steam d i s t i l l a t i o n e x t r a c t i o n t e c h n i q u e was found to e l i m i n a t e the large q u a n t i t i e s of coe x t r a c t e d i n t e r f e r e n c e s w h i c h result from soxhlet extraction. The direct i n j e c t i o n t e c h n i q u e can be c o m p l i c a t e d by DBD and DBF c o n t a m i n a n t s in coi n j e c t e d solvents, a l t h o u g h for the samples a n a l y z e d here, results o b t a i n e d by d i r e c t i n j e c t i o n were in r e a s o n a b l y good agreement with those o b t a i n e d by e x t r a c t i n g the s a m p l e and s u b j e c t i n g it to a l u m i n a fractionation. Results of a n a l y s e s by s e v e r a l different methods were in v e r y g o o d agreement, demonstrating the g e n e r a l reliability of the techniques d e v e l o p e d and i m p l e m e n t e d in this study.
REFERENCES
I.
2. 3. 4.
U.S. E n v i r o n m e n t a l P r o t e c t i o n A g e n c y (Feb., 1987). The N a t i o n a l Dioxin Stud~_~_Tiers 3, 5, 6, and 7, EPA Report 440/4-87-003, Office of Water R e g u l a t i o n s and Standards (WH-553), Washington, D.C. 20460. Amendola, G., D. Barna, R. Blosser, L. LaFleur, A. McBride, F. Thomas, T. Tiernan, and R. W h i t t e m o r e (1989). Chemosphere, 18, 1181-1184. Allen, L. H., R. M. Berry, B. I. Fleming, C. E. Luthe, and R. H. Voss (1989). Chemosphere, 19, 741-744. V e i t h , G. D., and L. M. K i w u s (1977). B u l l e t i n of E n v i r o n m e n t a l Contamination and Toxicology, 17, 631-636.
pp 1611-1618,
1990
0 0 4 5 - 6 5 3 5 / 9 0 $3.00 + .O0 P e r g a m o n Press DIc
D E T E R M I N A T I O N OF D I B E N Z O - p - D I O X I N (DBD) AND D I B E N Z O F U R A N (DBF) IN PAPER PULP M I L L D E F O A M E R A D D I T I V E S AND IN PAPER PULP SAMPLES
G. F. VANNESS,
T. O. TIERNAN*, M. S. HANES, C. J. REYNOLDS, D. J. WAGEL, and J. G. SOLCH
J. H. GARRETT,
D e p a r t m e n t of C h e m i s t r y and Toxic C o n t a i n m e n t R e s e a r c h P r o g r a m W r i g h t State U n i v e r s i t y , Dayton, Ohio, 45435, U.S.A.
ABSTRACT An a n a l y t i c a l p r o c e d u r e has b e e n d e v e l o p e d for q u a n t i t a t i v e l y m e a s u r i n g d i b e n z o - p - d i o x i n (DBD) and d i b e n z o f u r a n (DBF) p r e s e n t at p a r t - p e r - b i l l i o n l e v e l s in p a p e r m i l l d e f o a m e r s a n d p a p e r p u l p u s i n g g a s c h r o m a t o g r a p h y c o u p l e d w i t h e i t h e r low r e s o l u t i o n m a s s s p e c t r o m e t r y ( G C - L R M S ) or h i g h r e s o l u t i o n mass s p e c t r o m e t r y (GC-HRMS). KEYWORDS Dibenzodioxin, dibenzofuran, p r e c u r s o r s of P C D D / P C D F
analysis,
paper
pulp,
defoamer
formulations,
INTRODUCTION In 1987, the U. S, EPA r e l e a s e d a r e p o r t "The N a t i o n a l D i o x i n Study" w h i c h i d e n t i f i e d a p r e v i o u s l y u n s u s p e c t e d s o u r c e of 2 , 3 , 7 , 8 - T C D D c o n t a m i n a t i o n in some areas of the U.S., s p e c i f i c a l l y c e r t a i n types of p u l p and p a p e r m i l l s (i). This led to a more e x t e n s i v e a s s e s s m e n t of s e v e r a l p a p e r m i l l s (the Five Mill Study) w h i c h r e s u l t e d in the f i n d i n g of trace a m o u n t s of 2 , 3 , 7 , 8 T C D D and 2 , 3 , 7 , 8 - T C D F in b l e a c h e d p a p e r pulp, sludges, and e f f l u e n t s (2). Further investigation indicated that defoamer additives u s e d in p u l p manufacturing m i g h t s e r v e as s o u r c e s of d i b e n z o - p - d i o x i n (DBD) and d i b e n z o f u r a n (DBF) that could u n d e r g o c h l o r i n a t i o n to y i e l d T C D D and TCDF. P r e l i m i n a r y m e a s u r e m e n t s of the c o n c e n t r a t i o n of DBF in d e f o a m e r a d d i t i v e s s h o w e d levels w h i c h were h i g h e r than e x p e c t e d ( p a r t s - p e r - m i l l i o n ) , a l t h o u g h the p r e s e n c e of DBD was not c o n f i r m e d (3) . The p r e s e n t paper d e s c r i b e s a n a l y t i c a l p r o c e d u r e s r e c e n t l y d e v e l o p e d and i m p l e m e n t e d in our l a b o r a t o r y to d e t e r m i n e DBD and DBF levels in v a r i o u s d e f o a m e r f o r m u l a t i o n s and p u l p w h i c h may u n d e r g o c h l o r i n a t i o n in the course of p u l p m a n u f a c t u r i n g . The o b j e c t i v e of this work was to d e v e l o p more d e f i n i t i v e a n a l y t i c a l p r o c e d u r e s w h i c h w o u l d m i n i m i z e s a m p l e p r e p a r a t i o n p r i o r to GC-MS a n a l y s i s and w h i c h w o u l d a c h i e v e d e t e c t i o n limits of less than one p a r t - p e r - b i l l i o n . It was a l s o of i n t e r e s t to c o m p a r e analytical data obtained using GC-low r e s o l u t i o n mass s p e c t r o m e t r y (GC-LRMS) w i t h c o r r e s p o n d i n g d a t a o b t a i n e d u s i n g G C - h i g h r e s o l u t i o n mass s p e c t r o m e t r y (GC-HRMS). EXPERIMENTAL
PROCEDURES
A v a r i e t y of d e f o a m e r f o r m u l a t i o n s and paper p u l p s a m p l e s w e r e i n v e s t i g a t e d in this s t u d y in an e f f o r t to e s t i m a t e the range of c o n c e n t r a t i o n s of DBD and DBF p r e s e n t in such m a t e r i a l s . The c o m p o s i t i o n of m o s t of the c h e m i c a l d e f o a m e r f o r m u l a t i o n s t e s t e d h e r e had not b e e n d i s c l o s e d to our laboratory.
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1612
H o w e v e r , it w a s p o s s i b l e to g r o u p t h e s e d e f o a m e r formulations into two categories, oil-based and emulsified formulations, based upon visual i n s p e c t i o n of the m a t e r i a l s and s o l u b i l i t y tests w i t h h e x a n e and water. F i g u r e 1 i l l u s t r a t e s s c h e m a t i c a l l y the s a m p l e p r e p a r a t i o n and a n a l y s i s
0~i~, [~efoamer s, and
Pu]
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es
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alumlne romm o ra
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Choose ,th0
F i g u r e I. Schematic Diagram Showing Preparation Procedures Used in D e t e r m i n a t i o n of DBD and DBF in D e f o a m e r F o r m u l a t i o n s and Pulp s c h e m e d e v e l o p e d and u t i l i z e d in the p r e s e n t study. The oil s a m p l e s were p r e p a r e d u s i n g an a l u m i n a c o l u m n c l e a n u p . The emulsified formulation s a m p l e s and p a p e r p u l p s a m p l e s were p r e p a r e d u s i n g a steam d i s t i l l a t i o n p r o c e d u r e (4) f o l ~ o w e d by an a l u m i n a c o l u m n cleanup. F u l l y d e u t e r a t e d DBD and DBF were added to t h e s a m p l e s as i n t e r n a l standards prior to extraction. The s a m p l e e x t r a c t s w e r e a n a l y z e d by e i t h e r h i g h r e s o l u t i o n gas c h r o m a t o g r a p h y - low r e s o l u t i o n mass s p e c t r o m e t r y (HRGC-LRMS) or h i g h r e s o l u t i o n gas c h r o m a t o g r a p h y - high r e s o l u t i o n mass s p e c t r o m e t r y (HRGCHRMS). For p u r p o s e s of comparison, some d e f o a m e r s o l u t i o n s were a n a l y z e d d i r e c t l y by H R G C - H R M S , w i t h o u t prior c l e a n u p or s e p a r a t i o n , However, there are two s i g n i f i c a n t p r o b l e m s w i t h the d i r e c t analysis. First, if the sample is quite viscous, d i l u t i o n may be n e c e s s a r y for p r o p e r i n j e c t i o n into the gas c h r o m a t o g r a p h . A large d i l u t i o n a f f e c t s the d e t e c t i o n limit that can be achieved. Secondly, the p r e s e n c e of low levels of DBF in m a n y of the s o l v e n t s w h i c h can be used for d i l u t i o n of the s a m p l e p r e c l u d e s r e l i a b l e q u a n t i t a t i o n of the DBF in d e f o a m e r s that c o n t a i n low p a r t per b i l l i o n levels of this compound. S p e c i f i c d e t a i l s of the a n a l y t i c a l p r o c e d u r e s are p r e s e n t e d in the following.
1613
Sample
Preparation
i. Steam Distillation: Prewash the steam distillation apparatus (SDA), a n d c o n d e n s e r for a p e r i o d of one h o u r w i t h m e t h y l e n e c h l o r i d e , t h e n discard this solvent. P l a c e an a p p r o p r i a t e q u a n t i t y ( 2 5 0 - 5 0 0 mL) of h i g h purity water (HPLC G r a d e or e q u i v a l e n t ) i n t o the S D A flask, a n d add dsdibenzo-p-dioxin and ds-dibenzofuran to the f l a s k . A s s e m b l e the c o m p o n e n t s of the SDA, a d d i n g 10 m L of h i g h p u r i t y w a t e r a n d 10 m L of h e x a n e to the e x t r a c t o r of the SDA. O p e r a t e the a s s e m b l e d SDA for a p e r i o d of one hour, t h e n r e m o v e the o r g a n i c a n d a q u e o u s l i q u i d s f r o m the e x t r a c t i o n section u s i n g s e v e r a l h e x a n e r i n s e s a n d r e t a i n this s a m p l e for a n a l y s i s as a s y s t e m blank. E x t r a c t the a q u e o u s p h a s e w i t h h e x a n e to o b t a i n a f i n a l e x t r a c t for analysis. W a s h the e n t i r e S D A w i t h m e t h y l e n e c h l o r i d e as a f i n a l c l e a n i n g p r o c e d u r e . T r a n s f e r an a l i q u o t of the s a m p l e to the S D A flask, add dsdibenzo-p-dioxin and ds-dibenzofuran, a n d the a p p r o p r i a t e a m o u n t of h i g h p u r i t y w a t e r ( 2 5 0 - 5 0 0 mL). A t t a c h the S D A e x t r a c t o r to the flask, p l a c e I0 m L of h i g h p u r i t y w a t e r a n d h e x a n e i n t o the S D A e x t r a c t o r , and attach the c o n d e n s e r . E x t r a c t the s a m p l e for t h r e e h o u r s . R e p e a t the t r a n s f e r steps outlined above. C o n c e n t r a t e the f i n a l s a m p l e e x t r a c t to a v o l u m e of 5 m L in p r e p a r a t i o n for a l u m i n a c o l u m n c l e a n u p , or if the s a m p l e e x t r a c t is to be a n a l y z e d w i t h o u t f u r t h e r c l e a n u p , c o n t i n u e c o n c e n t r a t i n g to a v o l u m e of 90 pL. 2. Alumina Column Chromatoqraphy: For a s a m p l e w h i c h h a s n o t b e e n subjected to s t e a m d i s t i l l a t i o n , w e i g h an a l i q u o t of the s a m p l e into a s c r e w c a p vial. Add d.-dibenzo-p-dioxin and d s - d i b e n z o f u r a n standards, f o l l o w e d b y 2 m L of 5% (v/v) t o l u e n e in h e x a n e . T h o r o u g h l y m i x the s a m p l e and solvent. Chromatograph t h i s m i x t u r e on a c o l u m n c o n t a i n i n g I0 g of basic alumina ( a c t i v a t e d at 6 0 0 ° C ) , e l u t i n g the c o l u m n s e q u e n t i a l l y w i t h 30 m L of h e x a n e , 50 mL of 8% m e t h y l e n e c h l o r i d e in h e x a n e , a n d 45 m L of m e t h y l e n e c h l o r i d e , r e t a i n i n g o n l y the last e l u a t e f r a c t i o n . A d d 1 mL of t o l u e n e to the r e t a i n e d e l u a t e a n d c o n c e n t r a t e to a v o l u m e of 90 ~L at r o o m temperature, using a N-Evap concentrator. A d d i0 ~L of d 1 0 - p h e n a n t h r e n e to the c o n c e n t r a t e d e x t r a c t , a n d a n a l y z e the e x t r a c t by e i t h e r HRGC-HRMS or H R G C - L R M S . Extracts of s a m p l e s which have been previously steam distilled, as d e s c r i b e d above, are transferred directly to t h e a l u m i n a column and chromatographed just as d e s c r i b e d in the f o r e g o i n g p r o c e d u r e . 3. Direct Injection Technique: For s a m p l e s w h i c h are to be a n a l y z e d b y direct injection i n t o the G C - M S , w e i g h an a l i q u o t of the s a m p l e i n t o a vial, t h e n a d d 1 0 0 0 n g of the d . - D B D a n d d s - D B F i n t e r n a l s t a n d a r d s . Inject a p o r t i o n of this s a m p l e i n t o the H R G C - H R M S . If the s a m p l e is too v i s c o u s for direct injection, dilute it w i t h t o l u e n e initially, then add the d e u t e r a t e d i n t e r n a l s t a n d a r d s , a n d a n a l y z e the s a m p l e b y H R G C - H R M S . High
Resolution
Gas
Chromatography-Mass
Spectrometry
(HRGC-MS)
The HRGC-LRMS analyses for which results are presented herein were accomplished using a Hewlett-Packard 5980A Gas Chromatograph directly c o u p l e d to an E x t r e l E L Q - 4 0 0 Q u a d r u p o l e M a s s S p e c t r o m e t e r , o p e r a t e d in the selected ion monitoring mode. T h e c a p i l l a r y c o l u m n u s e d w a s a 60 m D B - 5 c o l u m n , 0 . 3 2 m m I.D., w i t h a f i l m t h i c k n e s s of 1.0 ~m, o p e r a t e d at 15 psi h e a d p r e s s u r e of h e l i u m . The analyte was injected by splitless injection (split at 45 s e c o n d s ) i n t o the c o l u m n w h i c h was m a i n t a i n e d at a t e m p e r a t u r e of 60°C. F o l l o w i n g i n j e c t i o n , the c o l u m n w a s h e l d at 6 0 ° C for 1 m i n u t e a n d t h e n the t e m p e r a t u r e w a s i n c r e a s e d at a r a t e of 1 5 ° C / m i n u t e to 180°C. The c o l u m n t e m p e r a t u r e w a s t h e n f u r t h e r i n c r e a s e d at a r a t e of 5 ° C / m i n u t e to a
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final t e m p e r a t u r e of 300°C, w h i c h was m a i n t a i n e d for I0 minutes. The mass s p e c t r o m e t e r was o p e r a t e d in the e l e c t r o n impact i o n i z a t i o n m o d e w i t h a s o u r c e t e m p e r a t u r e of 250°C. The ions m o n i t o r e d as i n d i c a t o r s of DBF were m/z 168 and m/z 139, w h i l e those m o n i t o r e d for the i n t e r n a l s t a n d a r d (dsDBF) were m/z 176 and m/z 146. The c o r r e s p o n d i n g ions m o n i t o r e d for DBD w e r e m/z 184 and m/z 128, and m/z 192 and m/z 136 for ds-DBD. The ion m o n i t o r e d as an i n d i c a t o r of the e x t e r n a l standard, d 1 0 - p h e n a n t h r e n e , was m/z 188. The H R G C - H R M S a n a l y s e s were a c c o m p l i s h e d u s i n g a C a r l o - E r b a M e g a 5000 Gas C h r o m a t o g r a p h c o u p l e d via jet s e p a r a t o r to a Kratos M S - 2 5 Mass S p e c t r o m e t e r e q u i p p e d w i t h a D S - 9 0 E Data System. The mass s p e c t r o m e t e r was o p e r a t e d in the s e l e c t e d ion m o n i t o r i n g mode. The c a p i l l a r y GC c o l u m n u s e d was a 30 m DB-5, 0.25 mm I.D. w i t h a film t h i c k n e s s of 1.0 Dm o p e r a t e d at 30 psi h e a d p r e s s u r e of hydrogen. The a n a l y t e was i n j e c t e d by s p l i t l e s s i n j e c t i o n onto the c o l u m n w h i l e the c o l u m n t e m p e r a t u r e w a s m a i n t a i n e d at 6 0 ° C . This t e m p e r a t u r e was m a i n t a i n e d for one m i n u t e f o l l o w i n g injection. The c o l u m n t e m p e r a t u r e was then i n c r e a s e d at 2 0 ° C / m i n u t e to a final t e m p e r a t u r e of 200°C, and h e l d at that t e m p e r a t u r e for 10 minutes. The mass s p e c t r o m e t e r was operated in the e l e c t r o n i m p a c t i o n i z a t i o n mode, with a source t e m p e r a t u r e of 300°C, a n d the a c c e l e r a t i n g v o l t a g e at 4 kV. The ions m o n i t o r e d as i n d i c a t o r s of the v a r i o u s c o m p o u n d s to be s e l e c t e d were: DBF, m/z 168 and m/z 169; ds-DBF, m/z 176; DBD, m/z 184 and m/z 185; and dg-DBD, m/z 192. The ion m o n i t o r e d for the e x t e r n a l standard, d, 0 - p h e n a n t h r e n e , was m/z 188. RESULTS R e s u l t s of a n a l y s e s of oil d e f o a m e r s a m p l e s p r e p a r e d b y a l u m i n a c o l u m n c h r o m a t o g r a p h y and a n a l y z e d by H R G C - H R M S are shown in T a b l e i. Sample c o n c e n t r a t i o n levels r a n g e d from none detected, w i t h d e t e c t i o n limits in the range from 1.2-64 ppb of DBD and 25 ppb - ii ppm of DBF. Average internal standard recoveries achieved for d.-DBD and ds-DBF in t h e s e a n a l y s e s w e r e 56 a n d 74 p e r c e n t , respectively, indicating that the a n a l y t i c a l m e t h o d o l o g y a p p l i e d is q u i t e acceptable. Table
i. D i b e n z o - p - d i o x i n and D i b e n z o f u r a n C o n c e n t r a t i o n s in D e f o a m e r Oils U s i n g A l u m i n a C o l u m n C l e a n u p and A n a l y s i s by H R G C - L R M S
Sample No. N7 N8 N9 NI0 NIl NI2 E1 E2 E3 E4 Lab Blank
Dibenzo-p-dioxin Conc. (ng/g) % Recovery a i0 ND(I.4) 4.9 4.9 5.0 ND(I.4) 2.4 64 i0 6.0 ND(I.2)
a d. - d i b e n z o - p - d i o x i n b ds - d i b e n z o f u r a n
62 50 74 71 71 83 25 41 61 63 18
Dibenzofuran Conc. (ng/g) % R e c o v e r y b 2400 25 93 55 20 25 32 Iii00 318 102 ND(0.03)
60 50 71 68 85 87 88 29 108 65 105
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TIC 227530 m/z 168 TIC 35218 m/z 169
TIC 421284 m/z 176
I
I
I
I
I
I
I
I
600 610 620 680 640 650 660 R.T. 7:46 7:54 8:02 8:09 8:17 8:25 8:83 Figure 2. Selected Ion Chromatogram Obtained by a Kratos MS26, DS-90E Mass Spectrometer for Sample No. X2
TIC 2361 A m~/z 1 ~ Ah
TIci49
/
TIC 229700 m/z 192 /
~
~
,-~
\
~.
I
I
I
I
I
I
I
I
R.T.
680 8:48
690 8:56
700 9:03
710 9:11
720 9:19
780 9:27
740 9:35
Figure 3. Selected Ion Chromatogram Obtained by a Kratos M825, DS-90E Mass Spectrometer for Sample No. X2
1616
TIC 5568 m/z 146 TIC 15616 m/z 176
TIC 454 m/z 139 TIC 1006 m/z 168
I
I
I
R.T. 19:00
I
I
19:20
I
I
19:40
20:00
Figure 4. Selected Ion Chromatogram Obtained by an ELQ-400 Quadrupole Mass Spectrometer for Sample No, N8
TIC 3296 m/z 136 TIC 7456 m/z 192
Tic 85
m/z 184
I R.T. 20:00
I
I
-
I
--I
20:20 20:40 Figure 5, Selected Ion Chromatogram Obtained by an Extrel ELQ-400 Quadrupole Mass Spectrometer for Sample No. N8
l 21:00
1617
T h e r e s u l t s o b t a i n e d for three paper pulp samples prepared by steam distillation followed by alumina column chromatography a r e s h o w n in T a b l e 2. As c a n be seen, n e i t h e r D B D n o r D B F w a s d e t e c t e d at a c o n c e n t r a t i o n in e x c e s s of the d e t e c t i o n l i m i t s .
T a b l e 2. Dibenzo-p-dioxin and Dibenzofuran Concentrations in P a p e r P u l p S a m p l e s U s i n g S t e a m D i s t i l l a t i o n F o l l o w e d by Alumina Column Cleanup and Analysis by HRGC-LRMS Dibenzo-p-dioxin Conc. (ng/g) % Recovery a
Sample No.
A5 A9 AI5 Lab Blank Lab blank
ND(3.7) ND(4.3) ND(4.0) ND(2.2) ND(2.6)
Dibenzofuran C_onc.(nq/g_) % Recovery b
52 40 41 29 31
ND(2.3) ND(I.8) ND(I.2) ND(I.4) ND(I.7)
52 41 40 30 33
s ds - d i b e n z o - p - d i o x i n b d8 - d i b e n z o f u r a n In o t h e r s t u d i e s , a set of f i v e d e f o a m e r samples were prepared and analyzed by three different quantitation techniques. In t h e s e tests, two o i l - b a s e d d e f o a m e r s a m p l e s w e r e p r e p a r e d in d u p l i c a t e , u s i n g a l u m i n a c o l u m n
Table 3.
WSU Sample No.
Comparisons of Data Obtained From Analyses of Defoamer Samples Using Different Analytical Procedures
Sample Matrix
HRGC-LRMS Results b
HRGC-HRMS Results a,b
Direct Injection HRGC-HRMS Results a,c
Dibenzofuran Xl X2 X3 X4 X5
Oil Oil Emulsion Emulsion Emulsion
3100 238 4100 723 8.1
2400 405 3402 802 11.3
Mean of Three Data Sets
Standard Deviation
(DBF)_
3059 684 4544 719 12
2853 442 4015 748 10.5
393 225 576 46.8 1.7
Dibenzo-p-Dioxin (DBD) Xl X2 X3 X4 X5 a.
b. c.
Oil Oil Emulsion Emulsion Emulsion
155 ND(6.4) 209 24.9 ND(0.13)
178 10.2 189 26.6 0.81
230 35.7 356 37.8 4.5
188 23.0 251 29.8 2.7
38.4 12.8 74.5 5.7 1.9
Mass resolution was 6000. Samples were extracted and the extracts were subjected to a full clean-up procedure, as described in the paper. Samples were diluted and injected directly into GC-MS, with no prior extraction or cleanup.
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chromatography, as a l r e a d y d e s c r i b e d , a n d the e x t r a c t s were analyzed s e p a r a t e l y by b o t h H R G C - H R M S and H R G C - L R M S . Three emulsified defoamer formulations were also p r e p a r e d in duplicate, using steam distillation, f o l l o w e d by a l u m i n a column chromatography, as d e s c r i b e d above, and these extracts were a n a l y z e d s e p a r a t e l y by both H R G C - L R M S and HRGC-HRMS. A third p o r t i o n of each of the five samples was p r e p a r e d by d i l u t i n g each sample d i r e c t l y with solvent, adding ds-DBD and d.-DBF internal standards, and d i r e c t l y a n a l y z i n g the d i l u t e d aliquots by HRGC-HRMS. The data o b t a i n e d from these several analyses are shown in Table 3. Typical s e l e c t e d - i o n mass c h r o m a t o g r a m s for DBF and DBD, which were o b t a i n e d in the analyses of Sample No. X2 by HRGC-HRMS, are shown in Figures 2 and 3, respectively. Corresponding mass c h r o m a t o g r a m s obtained in the H R G C - L R M S analyses of Sample No. N8 are shown in Figures 4 and 5. The set of ions m o n i t o r e d in the HRMS a n a l y s e s d i f f e r e d from those m o n i t o r e d in the LRMS analyses owing to the low signal r e s p o n s e s at m/z 169 for DBF, and at m/z 185 for DBD, w i t h the LRMS. Also, a s e c o n d a r y ion w a s m o n i t o r e d for each internal s t a n d a r d with the LRMS to p r o v i d e additional confirmation. CONCLUSIONS The data p r e s e n t e d h e r e i n indicate that for the samples a n a l y z e d in this study, the r e s u l t s for D B D and DBF o b t a i n e d by using HRGC-LRMS are c o m p a r a b l e to those o b t a i n e d by using HRGC-HRMS. The steam d i s t i l l a t i o n e x t r a c t i o n t e c h n i q u e was found to e l i m i n a t e the large q u a n t i t i e s of coe x t r a c t e d i n t e r f e r e n c e s w h i c h result from soxhlet extraction. The direct i n j e c t i o n t e c h n i q u e can be c o m p l i c a t e d by DBD and DBF c o n t a m i n a n t s in coi n j e c t e d solvents, a l t h o u g h for the samples a n a l y z e d here, results o b t a i n e d by d i r e c t i n j e c t i o n were in r e a s o n a b l y good agreement with those o b t a i n e d by e x t r a c t i n g the s a m p l e and s u b j e c t i n g it to a l u m i n a fractionation. Results of a n a l y s e s by s e v e r a l different methods were in v e r y g o o d agreement, demonstrating the g e n e r a l reliability of the techniques d e v e l o p e d and i m p l e m e n t e d in this study.
REFERENCES
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2. 3. 4.
U.S. E n v i r o n m e n t a l P r o t e c t i o n A g e n c y (Feb., 1987). The N a t i o n a l Dioxin Stud~_~_Tiers 3, 5, 6, and 7, EPA Report 440/4-87-003, Office of Water R e g u l a t i o n s and Standards (WH-553), Washington, D.C. 20460. Amendola, G., D. Barna, R. Blosser, L. LaFleur, A. McBride, F. Thomas, T. Tiernan, and R. W h i t t e m o r e (1989). Chemosphere, 18, 1181-1184. Allen, L. H., R. M. Berry, B. I. Fleming, C. E. Luthe, and R. H. Voss (1989). Chemosphere, 19, 741-744. V e i t h , G. D., and L. M. K i w u s (1977). B u l l e t i n of E n v i r o n m e n t a l Contamination and Toxicology, 17, 631-636.