Water round robin for parts-per-quadrillion determination of PCDDs and PCDFs

Chemosphere, Vol.20, N o s . l O - 1 2 Printed in Great Britain

WATER

pp 1313-1317,

1990

0045-6535/90 $3.00 + .00 Pergamon Press plc

ROUND ROBIN FOR PARTS-PER-QUADRILLION DETERMINATION OF PCDDsAND PCDFs

C. Tashiro (i)*, R.E. Clement (i), S. Davies (i), B. Oliver (2), T. Munshaw (3), J. Fenwick (4), B. Chittim (5), M.G. Foster (6)

(I) Ontario Ministry of Environment, Laboratory Services Branch, 125 Resources Road, Rexdale, Ontario, Canada, M9W 5LI. (2) ECO Logic, 143 Dennis St., Rockwood, Ontario, Canada, NOB 2K0. (3) Mann Testing Laboratories Ltd., 5550 McAdam Road, Mississauga, Ontario, Canada, L4Z IPI. (4) NovaLab Ltd., 9420 Cote de Liesse, Lachine, Quebec, Canada, H8T IAI. (5) Wellington Environmental Consultants Inc., 398 Laird Road, Guelph, Ontario, Canada, NIG 3X7. (6) Zenon Environmental Inc., 845 Harrington Court, Burlington, Ontario, Canada, L7N 3P3.

ABSTRACT As a part of the provincial Municipal Industrial Strategy for Abatement (MISA), the Ontario Ministry of Environment (MOE) carried out a round robin study on four litre spiked water samples to determine interlaboratory precision, accuracy and achievable detection limits for chlorinated dibenzo-p-dioxins (CDD) and chlorinated dibenzofurans (CDF). The results from the six participating laboratories are presented. KEYWORDS

Chlorinated dibenzo-p-dioxins, detection limits.

dibenzofurans,

round

robin,

water,

INTRODUCTION MISA is an MOE program that is currently being carried out to monitor contaminants in industrial and municipal effluents across the province in an effort to stop water pollution at the source. Effluents from the following five sectors are being monitored: municipal, pulp and paper, iron and steel, petroleum and organic chemical industries. Each industry/municipality is responsible for conducting the analysis of their own effluents and MOE also analyzes a number of audit samples. CDD and CDF are included in the monitoring program.

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Initially under the MISA program, 1.0L effluent samples were analyzed, b u t f i n d i n g s of low level d i o x i n s and furans in pulp and paper e f f l u e n t s and p e t r o l e u m r e f i n e r y e f f l u e n t s h a v e n e c e s s i t a t e d an increase of the s a m p l e size to 4 . 0 L (Clement, Thompson). To d e t e r m i n e the CDD/CDF MISA method detection limits achievable by experienced l a b o r a t o r i e s for 4.0L effluents, a r o u n d r o b i n was c a r r i e d out using w a t e r samples. The a n a l y s e s were c a r r i e d out by the p r i v a t e labs m e n t i o n e d in the t i t l e and by the MOE D i o x i n Lab on 4.0L spiked blank w a t e r s a m p l e s and the r e s u l t s are p r e s e n t e d here.

METHODS

S t u d y Design. Each l a b o r a t o r y was p r o v i d e d with five 4.0L b l a n k water s a m p l e s (JT B a k e r HPLC grade Water) that had been s p i k e d w i t h n a t i v e CDD and CDF at levels less than 1.0 ppt. The spikes w e r e p r e p a r e d by serial d i l u t i o n of s t o c k s o l u t i o n s o b t a i n e d from C a m b r i d g e I s o t o p e L a b o r a t o i e s and W e l l i n g t o n E n v i r o n m e n t a l Consultants. The labs also r e c e i v e d one unspiked blank water sample a n d an u n k n o w n standard mixture for quantitation. The labs were i n s t r u c t e d to use t h e i r own m e t h o d o l o g y and a final v o l u m e of 10-25 u L was suggested. [Fable 1 lists the clean-up and a n a l y s i s m e t h o d s used by the p a r t i c i p a t i n g laboratories.

TABLE I:

METHODOLOGY COMPARISON

MOE

ELI ECO

Mann

Nova

Wellington

Zenon

CLEAN-UP:

A. Extraction

1/1 pentane

i/1 CH2C12

1/1 CH2C12

i/1 CH2C12

i/1 CH2CI~

Modified silica Alumina

1/1 15% CH2CL2 In Hexane Modified silica Alumina

B. Column Clean-up

Modified silica Alumina

Modified silica Alumina Carbon

Modified silica Alumina

Modified silica Alumina

Finn 4500 25 2.5

HP5970 MSD I0 2

VG12000 I0 2

ANALYSIS:

A. GC-MS Finn TSQ70 B. Final Volume(~L) 10 C. Injection Volume(uL) 2 D. Surrogates Used (~3C~2-)

E. Peak Height or Area

TCDD PCDD HxCDD HpCDD OCDD Area

HP5970 MSD 2O 2 TCDD PCDD HxCDD HpCDD OCDD Area

TCDD OCDD

Area

TCDD OCDD

Area

TCDD PCDD HxCDD HpCDD OCDD Height

Finn TSQ70 25 I TCDD HxCDD OCDD

Area

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RESULTS

AND

DISCUSSION

Table 2 lists the average CDD and CDF c o n c e n t r a t i o n s in p g / u L obtained by the six l a b o r a t o r i e s for the 4L spiked w a t e r samples. Note that the l a b o r a t o r i e s have been given r a n d o m numbers and ND (not detected) values were not used in the c a l c u l a t i o n of the round robin average. The s t a n d a r d d e v i a t i o n o b t a i n e d by each lab is also g i v e n in order to d e t e r m i n e w i t h i n lab precision. The second column lists the expected c o n c e n t r a t i o n s b a s e d on the c o n c e n t r a t i o n of the stock s o l u t i o n used and the last column gives the overall average v a l u e o b t a i n e d for each congener. Each l a b o r a t o r y r e p o r t e d not d e t e c t e d v a l u e s for all congeners in the b l a n k w a t e r samples. TABLE 2:

CONCENTRATIONS OF PCDDs/PCDFs IN SPIKED 4L WATER SAMPLES - DATA SUMMARY (pg/L)

Average Value CONGENER

EXPECTED CONCENTRATION

TCDD PCDD HxCDD HpCDD OCDD

50 50 80 100 100

TCDF PCDF HxCDF HpCDF OCDF

25 25 40 50 50

LAB I

LAB 2

(Standard Deviation) LAB 3

167(38) 6 1 ( 4 ) 80(5) ND 39(4) 62(6) ND 80(8) 92(4) 58(25) 8 6 ( 2 7 ) 8 7 ( 5 ) 100(7) 1 2 5 ( 3 ) 141(4) ND ND ND ND ND

45(6) 36(2) 60(10) 179(26) 77(5)

32(2) 34(3) 46(3) 55(5) 71(7)

LAB 4

LAB 5

LAB 6

103(8) ND ND 59(6) ND

48(3) 51(4) 102(13) 74(5) 87(8)

51(2) 85(45) 37(6) 47(12) 94(11) 92(9) 80(15) 74(13) 84(8) 107(25)

70(10) 55(11) 49(8) 66(17) ND

23(2) 32(4) 47(3) 62(6) 38(2)

24(2) 20(I) 31(I) 30(3) 23(6)

ROUND ROBIN AVERAGE

40(20) 35(13) 47(10) 78(58) 52(26)

L a b o r a t o r i e s 1 and 4 had d i f f i c u l t y d e t e c t i n g a n u m b e r of the i s o m e r s e v e n t h o u g h t h e s a m p l e s w e r e s p i k e d at l e v e l s a b o v e the d e t e c t i o n limits of the instruments used in the study. L a b o r a t o r y 2 had c o n s i s t e n t l y high CDF results and L a b o r a t o r y 3 had h i g h CDD values. The r e m a i n i n g labs had good overall results w i t h s l i g h t l y lower results for the higher chlorinated congeners. The large standard deviations o b t a i n e d for TCDD, OCDD, TCDF, PCDF, HpCDF and OCDF i n d i c a t e s that these c o n g e n e r s may cause p r o b l e m s in real sample analysis. The w i t h i n - l a b p r e c i s i o n is quite good, w h e r e a s there is high b e t w e e n lab variability. T a b l e 3 c o n t a i n s the results for the u n k n o w n s t a n d a r d m i x t u r e that was i n c l u d e d in the study. A single isomer of each c o n g e n e r group was i n c l u d e d in the m i x t u r e and the e x p e c t e d c o n c e n t r a t i o n of each is given in c o l u m n two. The a v e r a g e v a l u e s w e r e s i m i l a r to the e x p e c t e d values w i t h the e x c e p t i o n of the H p C D D isomer. This d i s c r e p a n c y was also noted in a n o t h e r r o u n d robin u s i n g the same u n k n o w n m i x t u r e and is due to an i m p r o p e r s t a n d a r d i z a t i o n of the s t o c k s o l u t i o n (Tashiro). It was noted that as the d e g r e e of c h l o r i n a t i o n increased, the s t a n d a r d d e v i a t i o n of the average value also increased. Most laboratories performed s a t i s f a c t o r i l y in the a n a l y s i s of the standard.

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TABLE 3:

CONGENER

RESULTS FOR UNKNOWN STANDARD MIXTURE (pg/~L)

EXPECTED CONCENTRATION

LAB I

LAB 2

LAB 3

LAB 4

LAB 5

LAB 6

AVERAGE (S.D.)

TCDD PCDD HxCDD HpCDD OCDD

100 100 160 200 200

128 96 107 85 160

99 61 130 150 230

130 77 130 84 150

104 106 193 140 220

113 110 227 187 240

106 109 226 86 208

113(13) 93(20) 169(53) 117(50) 201(38)

TCDF PCDF HxCDF HpCDF OCDF

50 50 80 100 100

45 47 80 80 74

60 47 90 200 140

36 49 79 64 110

47 54 83 108 102

51 57 112 161 110

47 47 79 106 76

48(8) 50(4) 87(13) 120(51) 102(25)

The M I S A l a b o r a t o r y method d e t e c t i o n limits (MISA-MDL) for each l a b o r a t o r y are listed in Table 4. The M I S A - M D L protocol involves the a n a l y s i s of a series of replicate aliquots of reagent w a t e r spiked at levels not e x c e e d i n g 10 times the estimated MDL. This is followed by the c a l c u l a t i o n of the v a r i a n c e and standard d e v i a t i o n for each laboratory. The M I S A - M D L for each laboratory (Table 4) is s u b s e q u e n t l y determined by m u l t i p l y i n g the replicate standard d e v i a t i o n times the Student's t value for a 99% c o n f i d e n c e level (Environment Ontario). The M I S A - M D L is an i n d i c a t o r of l a b o r a t o r y p e r f o r m a n c e and allows i n t e r l a b o r a t o r y method comparison, but may not be applicable in d e f i n i n g q u a n t i t a t i o n limits for samples that introduce m a t r i x effects, such as pulp and paper samples.

TABLE 4:

LABORATORY METHOD DETECTION LIMITS FOR SPIKED 4.0L WATER SAMPLES (pg/L) (BASED ON MISA PROTOCOL)

CONGENER

LAB I

LAB 2

TCDD PCDD HxCDD HpCDD OCDD

171 NC NC 114 30

14 14 28 101 86

22 27 19 21 17

30 NC NC 23 NC

12 17 61 23 36

8 21 40 17 28

TCDF PCDF HxCDF HpCDF OCDF

NC NC NC NC NC

21 7 38 98 19

10 13 12 23 32

36 42 28 62 NC

7 20 14 25 7

8 3 2 11 21

NOTE:

LAB 3

NC = not calculated due to "not detected" values

LAB 4

LAB 5

LAB 6

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Based on the individual MISA-MDL listed in Table 4, the following CDD and CDF MISA-MDL were calculated according to the MISA protocol. The M I S A - M D L w e r e c h o s e n so t h a t at least two l a b o r a t o r i e s were successful at m e e t i n g this p e r f o r m a n c e c r i t e r i a b a s e d on single quadrupole GC/MS analysis. CONGENER

MISA MDL

TCDD PCDD HxCDD HpCDD OCDD

20 20 30 30 30

ppq ppq ppq ppq ppq

TCDF PCDF HxCDF HpCDF OCDF

15 15 20 30 30

ppq ppq ppq ppq ppq

It should be noted that these values are not instrumental detection limits, but they are a set of "clean matrix" method detection limits. The detectiom limits for a pulp and paper matrix will be higher.

CONCLUSIONS

Based on the precision estimates of the individual laboratories, MISA-MDL were calculated. The MISA-MDL values ranged from 15 ppq to 30 p p q for 4 . 0 L w a t e r s a m p l e s and s h o u l d be o b t a i n a b l e u s i n g single quadrupole GC/MS in the selected ion monitoring mode. The overall p e r f o r m a n c e of the l a b o r a t o r i e s was v a r i a b l e w h i c h i n d i c a t e s that further QA/QC protocols may be required in the MISA guidelines. Method detection limits for real effluent samples will be determined in a future round robin.

REFERENCES

Clement, R.E., Chemosphere, 19

S.A. (1989)

Suter, 649

E.

Reiner,

D.

McCurvin,

D.

Hollinger,

- 654.

Environment Ontario, "MISA - Estimation Queen's Printer for Ontario, 1988.

of Analytical

Detection

Limits"

Tashiro, C., R.E. Clement, S. Davies, T. Dann, P.Steer, M. Bumbaco, B. Oliver, T. Munshaw, J. Fenwick, B. Chittim, M.G. Foster, Chemosphere, this volume. Thompson,

T., R.E. Clement,

N. Thorton,

Chemosphere,

this volume.