218 
Table 82 shows the relevant MS parameters for the target compounds and their internal 
standards (ISTD). 
Table 82: Parameters of the target substances: molecular weight (MW), retention time (RT; GC 
conditions see above) and masses used for analysis in SIM mode (m/z) 
T arget-substances/ 
Internal standards 
MW 
RT 
El-Modus 
GC-MS (m/z) 
NCI-Modus 
Di 4 -Trifluralin 
349 
24.77 
267, 315 
349, 319 
Trifluralin 
335 
24.93 
264, 306 
335, 305 
Chlorpyriphos-methyl 
321 
28.83 
288, 286 
212, 141 
D io-Chlorpyriphos-ethyl 
359 
30.46 
326, 324 
322 
Chlorpyriphos-ethyl 
349 
30.59 
315, 199 
313 
D 4 -Endosulfan I 
408 
32.75 
237, 272 
376, 410 
Endosulfan I 
404 
32.82 
241, 265 
406, 372 
Endosulfan II 
404 
34.73 
241, 265 
406, 370 
6.6.3 Procedure for the analysis of Chlorpyrifos, Endosulfan and 
Trifluralin in water 
Water samples were taken at 5 m water depth using a 10 L glass bowl. Prior to solid 
phase extraction (SPE), the samples were acidified to pH 2.5-3.0 (25 % hydrochloric 
acid, p. a.). Di4-Trifluralin, Dio-Chlorpyrifos-ethyl, and D4-Endosulfan I (Dr. Ehrens- 
dorfer GmbH) were added as internal standards (e.g. 0.4 ng/L). The seawater was 
pumped through a column filled with 2 g Chromafix HR-P resin (Macherey and Nagel, 
Diiren) in a custom made extraction system. The loaded columns were dried and stored 
in the dark at 8°C until elution. All target substances were eluted with 100 ml 
dichloromethane in the opposite direction of sampling. After solvent change to hexane, 
the extracts were concentrated to 300 pi and analysed by GC-MS (see 6.6.2).