Ecological Archives A018-063-A3

David M. Walters, Ken M. Fritz, and Ryan R. Otter. 2008. The dark side of subsidies: Adult stream insects export organic contaminants to riparian predators. Ecological Applications 18:1835–1841.

Appendix C. Target PCB analytes and methods for extraction and analysis of samples by GC-ECD.

TABLE C1. Target PCB analytes determined by GC-ECD. Congener numbers are listed using the IUPAC nomenclature. Co-eluting congeners are listed in order of abundance in Aroclors 1242/1248/1254 (most abundant listed first).

Congener #

Congener #

Congener #

Congener #

Congener #

1

42/37

89

136

185

3

43

91

137

187/182

4/10

44

92

138/160/163

189

6

45

95

141/179

191

7/9

46

97

146

193

8/5

47/75

99

149/123

194

12/13

48

100

151

195/208

16/32

49

101/90

153/184

197

17/15

51

105

156

198

18

52

107/109/147

158

199

19

53

110/77

167

201/157

21

56/60

114

170/190

203/196

22

59

118

171/202

205

24/27

63

119

172

206

25

66

124

173

207

26

70/76

128

174

 

28

74

129/126

175

 

29

82

130

176

 

31

83

131

177

 

33/20

84

132

178

40

85

134

180

41/64/71

87/115/81

135/144

183

Sample Extraction: The sample was homogenized with anhydrous sodium sulfate and added to a Soxhlet extractor. Samples were Soxhlet-extracted for 18–24 hours, and then evaporated to 5 mL. The remaining extract was eluted through a drying column comprised of glass wool and 10 g anhydrous sodium sulfate and further cleaned using 4 g of activated alumni and 0.5 g Na2SO4 for water removal. Lipids were removed by centrifuging extracts with 2 mL concentrated sulfuric acid. Hexane was added into the extracts up to 10 mL and was then reduced to 2 mL under high purity nitrogen gas. Eight mL of isooctane was added to the hexane extracts which were then concentrated to 2 mL.

Quantification of PCBs: GC parameters were modified from those described by Germann (1988) and Pakdeesusuk et al. (2003). Blank GC runs (isooctane only) were carried out approximately every five samples to check for analyte carry-over between injections. A check standard (0.3 μg/mL mixture of Aroclor 1260, 1254, and 1016) was run approximately every 12 samples, and mean GC-ECD response factors varied <10% among check standard analyses.

LITERATURE CITED

Germann, G. G. 1988. The distribution and mass loading of polychlorinated biphenyls in Lake Hartwell sediments. MS Thesis. Clemson University, Clemson, South Carolina, USA.

Pakdeesusuk, U., D. L. Freedman, C. M. Lee, and J. T. Coates. 2003. Reductive dechlorination of polychlorinated biphenyls in sediment from the Twelve Mile Creek arm of Lake Hartwell, South Carolina, USA. Environmental Toxicology and Chemistry 22:1214–1220.


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