Chemosphere, Vol. 31, Nos 9-12. pp. 2139-2152, 1998 0 1998 Elsevier Science Ltd

All rights reserved. Printed in Great Britain 0045.6535/98 $19.00+0.00

PII: SO0456535(98)00276-S

PARTITION CONSTANTS OF CHLORINATED DIBENZOFURANS AND

DIBENZO-P-DIOXINS

Harrie A. J. Covers and Hildo B. Krop

Department of Environmental and Toxicological Chemistry, ARISE, University of Amsterdam,

Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands

Abstract

Vapour pressure, aqueous solubility, Henry law constant, n-octanol- and sediment-water partition

coefficient and bioconcentration factor of all chlorinated dibenzofurans (PCDF) and dibenzo-p-dioxins

(PCDD), in addition to those of the parent compounds DF and DD, were calculated via the SOFA (SOlubi-

lity parameters for Fate Analysis)- model. The derivation of these 1272 values was based on 120

experimental data. Mean deviation of calculated values from experimental data amounted to 0.39,0.25, 0.3 1,

0.19, 0.34 and 0.18 log units for the properties mentioned. The values of all compounds were tabulated.

Variation of values within isomer groups turned out to be the highest for vapour pressure of the tetra

substituted group, but were below 1.40 orders of magnitude. Variation in the complete series amounted to

7.78 orders at a maximum, again for vapour pressure. Accurate, almost linear, relationships were established

between the n-octanol-water partition coefficient and aqueous solubility and sediment-water partition

coefficient, whereas a parabolic relationship turned out to hold with the bioconcentration factor.

01998 Elsevier Science Ltd. All rights reserved

Introduction

The last few years reviews have been published on the fate determining conservative properties of

PCDF/D, collected, o.a., in the handbook of Mackay, Shiu and Ma [l]. Yet the data-sets are incomplete,

even at the level of the seventeen 2378-substituted congeners.

We have recently developed the SOFA model using methyl-chloro-benzenes as pilot compounds [2] and

applied it succesfully to the compound series of polychlorinated biphenyls (PCBs) [3], benzyltoluenes

(TCBTs) [4] and PCDF/Ds [5,6].

The model allows for a consistent description of all equilibrium partitioning properties and of the

relationships between them. Partition properties and their relationships are explained in terms of the single

2139

2140

component parameters molar liquid volume (V/cm3.mol’), heat of vaporization (AH/cal.mol-‘) and solubility

parameter or cohesion energy density (6/[cal.cm-3]“2), derived from these by 6’= (AH-RT)N, with R (Cal.

moll’.deg-‘) as gas constant and T (K) as absolute temperature. These key parameters are included in the

model for both the solute and the phases, they are partitioning over. So far predictions turned out to be

accurate, enabling the discrimination between isomer values even at the level of accurate chromatographic

retention data. SOFA is a thermodynamic lattice model. The quantification of the specific enthalpic and

entropic contributions to the partitioning process and of its temperature dependence are possible.

In order to complete available data sets the (subcooled) liquid vapour pressure (P/Pa), aqueous solubility

(S/mol.l“), Henry law constant (H /kPa.m’.mol-‘), n-octanol-water partition coefficient (K,,), sediment (par-

title)-water partition coefficient (K,,) and bioconcentration factor or biotic (guppy) lipid-water partition

coefficient ( Kba ) at 25°C are calculated for PCDFiD and their parents DF and DD.

Method

The SOFA model has been explained in detail elsewhere [2,3,4,5,6]. The basic equations for the

vapour pressure (P,), solubility (S,J and the partition coefficients (K,,,,) of compound i over the phases s

(= n-octanol, o; = sediment, p; or = biotic lipid, b) and water (w) read:

In P, = a, +c,,,ln A, -b,AH,/RT (1)

In S,,, = -v,[&~ +&’ -2~,~,~,,,,,(~,.,,,~,+6,)~(6,+~~,,,~~~)1~~~

-X,,, -c,,,,,ln A, -ln(V,/VJ +V,N, -1 -ln(VJ103) (2)

ln K,,,,= -V,[6,2 +&* -~~,S,C,,,,,(C,.,,,S,+~,)/(~,+C~.,,~S,)I’RT

+xw,w +c3,,.,w In A, +V,N, -V,N, (3)

Henry law constants can be derived directly from vapour pressure and solubility data by a log H= 1ogP -logs

type relationship.

Apart from the key descriptors (AH, V and 6) the following additional constants appear in these equations:

- a, X and c1 containing terms quantify (exchange) substitutional and orientational disorder entropic

contributions, where Ai is a molecular descriptor accounting for the number of orientations a solute molecule

2141

can take at a lattice site,

- b, c, and c2 containing terms quantify (exchange) enthalpic contributions: when c,=l and c,=l simple

Scatchard-Hildebrand solubility parameter models result. Deviations from 1 indicate specific interactions.

such as hydrogen bond formation, leading to non-ideal behaviour,

- V,N, containing terms quantify combinatorial entropy effects, accounting for size differences between

solute and solvent molecules similar to Flory-Huggins models.

AH, V and 6 values of all (PC)DF/D solutes have been derived from gas chromatographic retention data [6].

A, values of these solutes were directly derived as previously from the numbers of various atoms within a

molecule.

V and 6 values of s and w phases were all taken from the literature [2,3,4,5,6], except for the sediment

phase (p), where methylsalicylate was taken as a model compound with V = 130.43 cm3.mol and 6 = 10.6

[cal.cm-3]“2 [7,8].

a, b, X and c parameters are constants characteristic for the entire series of compounds or the series in

combination with a certain phase. They were determined by nonlinear regression fitting procedures. Starting

values for these constants were taken from previous calculations or theoretical considerations.

All calculations were carried out by the GWBASIC SOFA software on a Highscreen Pentium personal

computer with a 60 Mhz Intel microprocessor. Once key descriptors are available less than 30 minutes were

required for nonlinear regression. The programme provides as statistical data: the number of data points (N),

mean deviation of calculated values from experimental data (<dev>), correlation coefficient (r, not corrected

for degrees of freedom) and 95% confidence limits of derived a, b, X and c constants.

From calculated values of log K,,, log S,, log Krw and log Kbw, relationships between these properties were

calculated using the SGPLUS (1993, OASIS b.v., Nieuwe Gein, The Netherlands) software.

Results and discussion

General

Calculations resulted in a set of 1272 values derived from only 120 experimental data tabulated in

Table 1. a, b, X and c constants derived (not shown here) were not statistically significant in some cases and

the corresponding term could be removed from eqs. (l)-(3). This holds for c3 orientational exchange entropy

terms of K,, and Krw in contrast to the P, S, H and K,,,,, cases. The c,,~ constant of K,,, Krw and K,, could

be fixed at the value of 1 indicating the absence of strong interaction between solute and solvent in the

relatively moderately or a-polar s phases. Some statistics of these derivations are included in the last three

lines of Table 1. Mean deviations from experimental data are of the same order of magnitude as the errors

in experimental data. However both experimental and calculational errors turn out to be too high in many

2142

cases in order to reliably distinguish (small) isomer differences. Correlation coefficients are high when the

range of values is sufficiently wide.

Relationships between partition constants

Previously, it has already been shown and explained that an accurate non-linear relationship between

calculated log K,,v and log K,, values exists [9], especially when the DF and DD series are treated

separately. The -log S, or IogK,, and log K,, relationships turned out to be close to linearity. Relationships

are summarized in equations (4)-(6):

Log K,, = -(l. 177kO.193) +(2.010+0.062).Log K,, -(0.164+0.005).(Log K,$

N=136 PCDFs; r=0.945; s.e.r.=0.06; F=560

Log KbW = -(4.534+0.425) +(3.065+_0.127).Log K,, -(0.232&0.009).(Log K,)’

N=76 PCDDs; r=0.948; s.e.r.=0.07; F=322

-Log S, = -(0.476*0.223) +(0.977*0.072).Log K,, +(0.023&0.006).(Log K,,J’

N=136 PCDFs; r=0.998; s.e.r.=0.07; F=16690

-Log S, = -(0.005+0.341) +(0.971fO.l02).Log K,, +(0.015fO.O08).(Log K,,)*

N=76 PCDDs; r=0.998; s.e.r.=0.06; F=9528

Log K,, = -( 1.393+0.061) +( 1.288+0.02O).Log K,, +(0.008+0.002).(Log K,,)’

N=l36 PCDFs; r=0.9999; s.e.r.=0.02; F=268747

Log K,, = -( 1.062+0.133) +( 1.173?0.04O).Log K,, +(0.017fO.O03).(Log K,,,)’

N=76 PCDDs; r==O.9998; s.e.r.=0.02; F=90744

(44

(4b)

(54

(64

(6b)

The accuracy of these relationship is higher then can be obtained by correlating experimental data. The

experimental data have inaccuracies slightly higher than standard errors of regression (ser.) of equations

(4)-(6). The high accuracy of the latter are caused by the similarities of the model equations (2)-(3) and the

use of identical key descriptors AH, V and 6 for the (PC)DD/F in these equations.

Specific comments

As Table 1 shows, the highest (but still small) variation within isomer groups, not exceeding 1.39

2143

orders of magnitude, was calculated for the vapour pressure of the tetra-substituted compounds, whereas the

highest variation in the complete series amounts to 7.78 orders (for vapour pressure again).

Only 2 orders of magnitude (or a factor of 100) variation is present in the complete series for Henry law

constant and bioconcentration. The former is caused by compensating effects in vapour pressure and solubi-

lity, the latter by the solubility properties and entropic effects of lipids [9]. For Henry law constants of tetra-

chlorinated TCBTs much larger variation has been found, leading to large variation in the environmental fate

of these flexible and nonplanar isomers [4]. It can, therefore, be expected that PCDFiD isomers behave more

similarly in fate models. Yet, isomer differences for PCDD/F turned out to be important in the case of

chromatographic retention. SOFA performed quite well in the prediction of retention on different columns

[6]. It cannot be excluded that prediction of receptor binding affinities by SOFA, as currently under

development, may reveal substantial differences between isomers as well.

With respect to sediment-water partitioning, note the high K,, values, which are a consequence of the

specific sediments used in the experimental determination, which possibly were contaminated by mineral oil

[5]. Moreover, the experimental determination of these K,, values was based on a cosolvent method using

methanol-water mixtures as an aqueous phase and subsequent extrapolation to 0% methanol. It is not yet

clear whether high K,, values result from the methanolic influence on the sediment phase or that the

cosolvent method is more accurate than other methods suffering from difficulties in determining low amounts

of solute in the aqueous phase.

Finally, calculated bioconcentration factors are based on experimental data of congeners not showing

biotransformation [9,15]. Yet many other congeners may biotransform, expecially the non 2378 substituted

ones. In these cases calculated values of K,, have to be considered as (hypothetical) maximum values.

Table 1. Calculated and experimental (in italics) values of subcooled liquid vapour pressure and aqueous solubility, Henry law constant, n-octanol-water and sediment-water partition coefficient and lipid weight based bioconcentration factors in the guppy at 25°C of all 212 (PC)DF/D and statistics of the SOFA model.

Compound* -LogP” -LogSb -LogH’ LogK,wd LogK,,’ LogK,wf Pa mol.l-’ kPa.m3 l.kg-’

.mol-’

1. DF -0.91 3.43 1.67 3.68 3.45 4.08 -0.15 3.99 1.86 3.92 3.68

2. 1 0.06 4.16 1.92 4.33 4.35 4.46 4.33

3. 2 0.27 4.24 2.04 4.37 4.38 4.51 4.37

4. 3 0.31 4.22 2.11 4.35 4.34 4.53 4.35

5. 4 0.30 4.37 1.95 4.44 4.49 4.48 4.44

6. 12 1.29 5.13 2.17 5.10 5.40 4.74

2144

7. 13

8. 14

9. 16 1.16 5.00 2.16 5.03 5.31

10. 17 1.16 4.89 2.29 4.96 5.19

11. 18 1.36 4.97 2.40 4.99 5.22

12. 19 1.69 5.40 2.31 5.22 5.55

13. 23 1.55 5.20 2.36 5.11 5.39

14. 24 1.25 5.00 2.27 5.01 5.27

15. 26 1.37 5.13 2.25 5.09 5.38

16. 27 1.30 5.01 2.30 5.02 5.27

17. 28

18. 34

19. 36

20. 37

21. 46

22. 123 2.33 5.89 2.46 5.72 6.25

23. 124 2.09 5.72 2.39 5.64 6.15

24. 126 2.27 5.92 2.36 5.75 6.30

25. 127 2.19 5.83 2.37 5.70 6.23

26. 128 2.51 5.94 2.59 5.73 6.25

27. 129 3.04 6.37 2.68 5.96 6.54

28. 134 2.13 5.69 2.45 5.62 6.11

29. 136 2.07 5.57 2.52 5.44 6.00

30. 137 2.08 5.48 2.61 5.49 5.92

31. 138 2.15 5.54 2.62 5.52 5.96

32. 139 2.57 5.94 2.64 5.73 6.24

33. 146 2.21 5.67 2.55 5.60 6.07

34. 147 2.11 5.63 2.50 5.58 6.06

35. 148 2.27 5.70 2.59 5.60 6.08

36. 149 2.60 6.08 2.54 5.82 6.37

37. 234 2.57 6.10 2.49 5.83 6.40

38. 236 2.56 6.04 2.53 5.80 6.34

1.05 4.76 2.31 4.88

1.09 4.94 2.17 4.99

1.38 5.05 2.34 5.04 I.84 5.64 2.20 5.30

1.57 5.32 2.27 5.19

1.45 5.13 2.34 5.08

1.46 5.01 2.47 5.00

1.54 5.20 2.35 5.11

5.09

5.26

5.30

5.51

5.35

5.23

5.40

4.78

4.73 4.99

4.73

4.78

4.83 4.99

4.81

4.82

4.78

4.77

4.79 5.02

4.81 5.04

4.79

4.81

4.86

4.82 5.11

4.92

4.89

4.88

4.89

4.98

5.04

4.91

4.93

4.97

4.98

5.00

4.95

4.93

4.97

4.96

4.94

4.96

2145

39. 237 2.49 5.95 2.55 5.74 6.27 4.96

40. 238 2.44 5.97 2.49 5.76 6.30 4.94

41. 239 2.51 5.87 2.66 5.69 6.18 5.01

42. 246 2.37 5.77 2.62 5.64 6.12 4.99

43. 247 2.20 5.72 2.49 5.63 6.12 4.93

44. 248 2.24 5.74 2.51 5.64 6.14 4.94

45. 249 2.22 5.63 2.61 5.57 6.02 4.97

46. 346 2.73 6.12 2.63 5.82 6.37 5.01

47. 347 2.64 6.06 2.59 5.80 6.34 4.98

48. 348 2.43 6.05 2.40 5.81 6.38 4.91

49. 349 2.31 5.90 2.43 5.73 6.27 4.91

50. 1234 3.17 6.63 2.56 6.34 7.12 4.92

51. 1236 3.23 6.64 2.61 6.34 7.11 4.94

52. 1237 3.15 6.58 2.59 6.31 7.07 4.93

53. 1238 3.34 6.66 2.70 6.34 7.10 4.98

54. 1239 3.96 7.07 2.90 6.54 7.35 5.08

55. 1246 3.09 6.40 2.71 6.20 6.91 4.97

54. 1247 2.91 6.38 2.54 6.21 6.94 4.90

57. 1248 3.18 6.46 2.74 6.23 6.95 4.98

58. 1249 3.72 6.86 2.87 6.43 7.20 5.06

59. 1267 3.21 6.78 2.45 6.43 7.26 4.88

60. 1268 3.25 6.53 2.74 6.26 7.00 4.99

61. 1269 3.83 7.00 2.85 6.50 7.31 5.05

62. 1278 3.45 6.79 2.68 6.41 7.20 4.97

63. 1279 3.71 6.88 2.84 6.44 7.22 5.05

64. 1289 4.30 7.34 2.98 6.67 7.52 5.13

65. 1346 3.17 6.39 2.80 6.18 6.88 5.01

66. 1347 3.07 6.38 2.71 6.18 6.89 4.97

67. 1348 3.10 6.42 2.70 6.21 6.93 4.97

68. 1349 3.52 6.78 2.76 6.40 7.17 5.01

69. 1367 3.14 6.44 2.71 6.22 6.94 4.97

70. 1368 2.93 6.16 2.79 6.06 6.71 5.00

71. 1369 3.40 6.59 2.83 6.29 7.02 5.03

72. 1378 3.22 6.42 2.81 6.20 6.90 5.01

73. 1379 3.36 6.47 2.90 6.22 6.91 5.06

74. 1467 3.28 6.53 2.77 6.26 6.99 5.00

2146

75. 1468

76. 1469

77. 1478

78. 1678

79. 2346

80. 2347

81. 2348

82. 2367

83. 2368

84. 2378

85. 2467

86. 2468

87. 3467

88. 12346

89. 12347

90. 12348

91. 12349

92. 12367

93. 12368

94. 12369

95. 12378

96. 12379 4.54 7.56 3.00 7.00

97. 12389 5.02 7.99 3.04 7.22

98. 12467 3.96 7.22 2.76 6.84

99. 12468 3.96 6.95 3.02 6.67

100. 12469 4.54 7.38 3.17 6.88

101. 12478 4.05 7.28 2.79 6.87

102. 12479 4.31 7.33 2.99 6.87

103. 12489 4.86 7.76 3.11 7.09

104. 12679 4.55 7.66 2.90 7.06

105. 13467 4.16 7.23 2.95 6.82

106. 13468 3.92 6.92 3.01 6.65

107. 13469 4.39 7.32 3.08 6.86

108. 13478 4.09 7.26 2.85 6.85

3.16 6.24 2.93

3.54 6.66 2.90

3.34 6.55 2.81

3.42 6.67 2.76

3.61 6.84 2.79

3.43 6.81 2.64

3.35 6.82 2.55

3.55 6.95 2.61

3.23 6.62 2.62

3.43 6.87 2.57 3.79 6.87 2.93

3.36 6.65 2.73

3.12 6.32 2.82

3.84 7.01 2.85

4.10 7.27 2.85

3.92 7.2% 2.65

4.07 7.34 2.74

4.68 7.71 2.99

4.09 7.49 2.62

4.01 7.21 2.81

4.67 7.66 3.03

4.21 7.50 2.72

6.09

6.32

6.27

6.34

6.42

6.42

6.44

6.50

6.33

6.46

6.33

6.15

6.51

6.86

6.89

6.91

7.08

7.00

6.83

7.04

6.99

6.74

7.05

6.99

7.10

7.21

7.23

7.25

7.33

7.10

7.29 7.86

7.08

6.83

7.32

7.83

7.89

7.91

8.12

8.05

7.80

8.07

8.03 7. 77

8.01

8.31

7.82

7.55

7.83

7.86

7.84

8.12

8.10

7.78

7.54

7.81

7.82

5.06

5.06

5.02

5.00

5.02

4.96

4.92

4.95

4.94

4.93

4.99

5.01

5.05

4.88

4.80

4.84

4.95

4.80

4.86

4.97

4.84

4.95

4.98

4.84

4.94

5.02

4.85

4.94

5.01

4.91

4.92

4.93

4.98

4.88

2147

109. 13479

110. 13678

111. 14678

112. 23467

113. 23468

114. 23478

115. 23489

116. 123467

117. 123468

118. 123469

119. 123478

4.24 7.27 2.98

4.05 7.19 2.88

4.28 7.25 3.05

4.52 7.70 2.84

4.16 7.36 2.82

4.26 7.68 2.59 4.71 7.47 3.24

4.25 7.54 2.72

4.89 8.08 2.83

4.76 7.79 2.99

5.43 8.19 3.25

4.86 8.15 2.72 5.25 8.67 2.58

5.20 8.17 3.04

5.62 8.58 3.06

4.92 8.22 2.72 5.23 8.28 2.96

5.31 8.31 3.02

5.50 8.39 3.13

5.65 8.64 3.02

6.84

6.81

6.82

7.09

6.91

7.11

7.02

7.48

7.31

7.49

7.53

120. 123479

121. 123489

122. 123678

7.51

7.72

7.57

123. 123679

124. 123689

125. 123789

7.58

7.61

7.76

126. 124678 4.87 7.92 2.97 7.38

127. 124679 5.18 8.00 3.19 7.40

128. 124689 5.45 8.09 3.38 7.43

129. 134678 4.96 7.92 3.05 7.37

130. 134679 5.15 7.96 3.20 7.38

131. 234678 5.12 8.38 2.75 7.65

132. 1234678 5.60 8.76 2.85 5.85 9.40 2.46

5.99 8.80 3.19

6.14 8.86 3.29

6.18 9.20 3.00

8.01

133. 1234679

134. 1234689

135. 1234789

8.00

8.02

8.23

136. 12346789 6.74 9.64 3.11 8.60 6.15 9.28 2.88 8.78

7.80

7.77

7.76

8.15

7.90

8.20 8.05

8.07

8.72

8.47

8.70

8.80 8.83

8.74

9.03

8.85

8.84

8.87

9.08 9.28

8.58

8.57

8.58

8.55

8.54

8.96 8.56

9.48 9.97

9.43

9.45

9.76 9.78

10.30

4.93

4.89

4.96

4.89

4.87

4.79 5.14

4.84

4.61

4.66

4.78

4.57

4.70

4.72

4.58 4.95

4.69

4.74

4.71

4.66

4.75

4.84

4.69

4.75

4.59

4.26 4.46

4.38

4.42

4.32

3.88 10.49 3.90

137. DD 0.60 4.65 1.96 4.49 4.54 4.68 0.29 4.36 1.93 4.20 4.49

2148

138. 1

139. 2

140. 12

141. 13

142. 14

143. 16

144. 17

145. 18

146. 19

147. 23

148. 27

149. 28

150. 123

151. 124

152. 126

153. 127

154. 128

155. 129

156. 136

157. 137

158. 138

159. 139

160. 146

161. 147

162. 178

163. 237

164. 1234

165. 1236

166. 1237

167. 1238

1.66 5.43 2.24 5.17 1.12 4.92 2.20 4.75

1.63 5.31 2.34 5.10 1.14 5.24 1.90 5.08

2.74 6.24 2.51 5.84

2.46 5.89 2.58 5.65

2.53 6.04 2.50 5.74

2.60 6.11 2.50 5.78

2.57 6.03 2.56 5.73

2.61 6.05 2.58 5.74

2.98 6.26 2.73 5.84

2.71 6.12 2.60 5.77 2.03 5.86 2.18

2.46 5.93 2.55 5.68 2.09 6.00 2.09 5.75

2.58 5.95 2.64 5.68 2.61 5.93 2.67

3.58 6.85 2.75 6.40

3.38 6.66 2.74 6.29 2.97 6.55 2.42 6.45

3.56 6.86 2.71 6.41

3.44 6.80 2.66 6.38

3.60 6.84 2.78 6.39

3.98 7.03 2.96 6.47

3.32 6.53 2.80 6.22

3.29 6.47 2.83 6.19

3.21 6.47 2.75 6.19

3.66 6.66 3.01 6.27

3.74 6.78 2.97 6.34

3.36 6.60 2.78 6.26

3.57 6.80 2.79 6.36

3.45 6.72 2.75 6.33

4.27 7.42 2.87 6.92 3.72 7.20 2.52 7.08

4.32 7.43 2.91 6.92

4.20 7.39 2.83 6.91 4.55 7.30 3.24 6.91

4.25 7.41 2.85 6.92

5.46

5.35

6.38

6.11

6.24

6.29

6.22

6.23

6.34

6.27

6.15 5.37

6.14 5.42

7.15

7.01

7.16 5.51

7.13 5.48

7.13 5.54

7.21 5.64

6.90 5.54

6.85 5.55

6.87 5.51

6.93 5.65

7.03 5.63

6.95 5.53

7.09 5.54

7.05 5.52

7.88 5.52

7.88 5.54

7.87 5.50

7.88 5.51

5.08 5.17

5.12 5.09

5.37

5.39

5.36

5.36

5.38

5.39

5.48

5.41

5.52

5.51

2149

168. 1239

169. 1246

170. 1247

171. 1248

172. 1249

173. 1267

174. 1268

175. 1269

176. 1278

177. 1279

178. 1289

179. 1368

180. 1369

181. 1378

182. 1379

183. 1469

184. 1478

185. 2378

186. 12346

187. 12347

188. 12367

189. 12368

190. 12378

191. 12467 5.14 7.99 3.16 7.40 8.55

192. 12468 4.98 7.67 3.33 7.21 8.27

193. 12469 5.41 7.86 3.56 7.30 8.34

194. 12478 4.80 7.86 2.96 7.36 8.51

195. 13467 5.30 8.04 3.28 7.42 8.55

196. 13468 4.90 7.67 3.25 7.22 8.29

197. 14678 5.26 7.99 3.29 7.39 8.51

198. 23467 5.42 8.29 3.15 7.56 8.77

199. 23468 5.10 7.92 3.19 7.36 8.49

200; 123467 5.87 8.70 3.19 7.97 9.36

4.70 7.58 3.14 6.98

4.46 7.33 3.15 6.84

4.01 7: 17 2.85 6.79

4.13 7.19 2.95 6.79

4.51 7.35 3.17 6.85

4.31 7.57 2.76 7.01

4.19 7.26 2.95 6.83

4.62 7.49 3.15 6.93

4.36 7.55 2.83 6.99

4.45 7.39 3.08 6.88

4.89 7.78 3.13 7.09

3.84 6.91 2.94 6.64 4.24 7.08 3.15 7.13

4.34 7.14 3.22 6.74

4.08 7.20 2.90 6.80

4.26 7.04 3.23 6.68

4.76 7.36 3.42 6.83

4.24 7.31 2.96 6.85

4.24 7.47 2.79 6.96 3.93 7.45 2.48

5.28 8.05 3.25 7.43

4.82 7.92 2.91 7.39 5.37 7.73 3.65 7.44

4.99 8.13 2.89 7.50

4.76 7.80 2.98 7.32

4.92 8.11 2.83 7.50

7.92 5.65

7.74 5.65

7.71 5.50

7.70 5.55

7.75 5.66

8.02 5.48

7.75 5.55

7.85 5.65

7.99 5.51

7.80 5.62

8.07 5.66

7.50 5.53

7.58 5.67

7.72 5.52

7.51 5.67

7.68 5.78

7.78 5.55

7.95 5.48 7.68 5.24

8.57 5.52

8.57 5.37

8.72

8.46

8.72

5.36

5.39

5.34 5.27

5.48

5.54

5.67

5.38

5.53

5.51

5.54

5.48

5.49

5.21

2150

201. 123468

202. 123469

203. 123478

204. 123678

5.59

6.10

5.41 5.57

5.48

205. 124678 5.70

206. 124679 5.85

207. 134678 5.75

208. 134679 5.97

209. 234678 5.86

210. 1234678

211. 1234679

212. 12346789

6.23 6.22

6.47

6.87 6. 73

8.35 3.26

8.52 3.60

8.59 2.84 8.37 3.20

8.65 2.84

8.49 3.23

8.32 3.55

8.51 3.25

8.35 3.64

8.79 3.08

9.17 3.08 8.86 3.36

8.97 3.51

9.60 3.29 9.85 2.88

7.77

7.83

7.94 7. 79

7.98

7.85 9.19

7.73 8.99

7.86 9.20

7.73 8.98

8.02 9.45

8.40 10.00 8.20 10.95

8.25 9.75

8.75 10.50 8.60 10.96

9.09

9.11

9.37

9.42

5.23

5.39

5.07 5.01

5.08 4.94

5.23

5.36

5.24

5.41

5.18 4.93

4.79 4.68

4.95

4.39 4.13

PCDFiD -0.91- 3.43- 1.67- 3.68- 3.45- 3.68- All 6.87 9.64 3.64 8.75 10.50 5.78

N 23 23 23 15 12 24

<de+ 0.39 0.25 0.31 0.19 0.34 0.18

r 0.98 0.98 0.71 0.99 0.95 0.87

* Given are a serial number of each compound and the substitution pattern of the PCDF/D congener. a Experimental data from Ref. l), corrected or averaged by 10) with 11). b Experimental data from Ref. l), corrected and averaged by 12), 16) and 13). ’ Inferred from P and S by the relationship log H = log P -log S +6, the factor of 6 accounting for proper treatment of units. d Experimental data from Ref. 14). e Experimental data from Ref. 5). f Experimental data from Ref. 15).

Conclusions

A complete set of 212 values for each of the six partition constants was calculated, filling a

substantial gap in the availability of data. The inaccuracy of these values is close the inaccuracy of the

experimental data used for derivation. This meant that distinguishing between isomers is only partly possible.

Accurate theoretical (model) relationships were calculated between calculated n-octanol-water partition

coefficients, aqueous solubility, sediment-water partition constants and bioconcentration factors. Some

additional comments were given respect to the use of calculated data for specific partition constants.

2151

References

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

D. Mackay, W.Y. Shiu and K.C. Ma, Illustrated Handbook of Physical-Chemical Properties and

Environmental Fate of Organic Chemicals, Volume II. Lewis Publishers, Chelsea, U.S.A (1992).

H.A.J. Govers, Calculation of Partition Constants for a Series of Organic Compounds via a Novel

Solubility-parameter-based Method. J. Chem. Sot. Faraday Trans., 89, 3751-3759 (1993).

H.A.J. Govers and P. de Voogt, Gas Chromatographyic Derivation of the Solubility of

Polychlorinated Biphenyls with the Inclusion of Cis-Trans and Optical Isomerism and Orientational

Disorder. SAR and QSAR In Environ. Res., 3, 3 15-324 (1995).

A.G. van Haelst, Environmental Chemistry of Tetrachlorobenzyltoluenes. Ph.D. Thesis, University

of Amsterdam, Amsterdam ( 1996).

H. Loonen, Bioavailability of chlorinated dioxins and furans in the Aquatic Environment. Ph.D.

Thesis, University of Amsterdam, Amsterdam (1994).

H.A.J. Govers, F.W.M. van der Wielen and K. Olie, Derivation of solubility parameters of

chlorinated dibenzofurans and dibenzo[p]dioxins from gas chromtographic retention parameters via

SOFA. J. Chromatogr. A., 715, 267-278 (1995).

D.R. Lide (editor), Handbook of Chemistry and Physics, CRC Press, Boca Raton (1991).

Y-P. Chiou and W.J. Weber, Jr., Estimating the Effects of Dispersed Organic Polymers on the

Sorption of Contaminants by Natural Solids. 1. A Predictive Thermodynamic Humic Substance-

Organic Solute Interaction Model. Environ. Sci. Technol., 23, 978-984 (1989).

H.A.J. Govers, H. Loonen and J.R. Parsons, Nonlinear dependence of bioconcentration factors on

n-octanol-water partition coefficients of chlorinated dibenzofurans and dibenzo-p-dioxins. SAR and

QSAR in Environ. Res., 5, 63-78 (1996).

B.F. Rordorf, Prediction of vapor pressures, boiling points and enthalpies of fusion for twenty-nine

halogenated dibenzo-p-dioxins and fifty-five dibenzofurans by a vapor pressure correlation method.

Chemosphere 18, 783-788 (1989).

B.D. Eitzer and R.A. Hites, Vapor Pressure of Chlorinated Dioxins and Dibenzofurans. Environ. Sci.

Technol., 22, 1362-1364 (1988).

K.J. Friesen and G.R.B. Webster, Temperature Dependence of the Aqueous Solubilities of Highly

Chlorinated Dibenzo-p-Dioxins. Environ. Sci. Technol., 24, 97- 10 1 (1990).

K.J. Friesen, J. Vilk and D.C.G. Muir, Aqueous solubilities of selected 2,3,7,8_substituted

polychlorinated dibenzofurans (PCDFs). Chemosphere 20, 27-32 (1990).

L.P. Burkhard and D.W. Kuehl, N-octanol/water partiton coefficient by reverse phase liquid

chromatography/mass spectrometry for eight tetrachlorinated planar molecules. Chemosphere 15,163-

167 (1986).

2152

15. H. Loonen, M. Tonkes, J. Parsons and H.A.J. Govers, Bioconcentration of polychlorinated dibenzo-p-

dioxins and polychlorinated dibenzofwans in guppies after aqueous exposure to a complex

PCDDIPCDF mixture: Relationship with molecular structure. Aquat. Toxicol., 30, 153-169 (1994).

16. W.J. Doucette and A.W. A&en, Aqueous Solubility of Selected Biphenyl, Furan, and Dioxin

Congeners. Chemosphere 17, 243-252 (1988).