Appendix D: Analytical Methods 



Before leaving the site, a picture of the sampling location should be taken, other ancillary 

 observations that are specified elsewhere should be recorded and the note book should be checked 

 for completeness. 



Two of the jars from each sampling location will be transported to the appropriate regional 

 analytical laboratory. The other jar will remain in the country at the laboratory assigned by the 

 country. 



3. Sample Extraction and Clean-up 



3.1 Principles 



Lipids are extracted from an aliquot of a sample by solvent extraction, fractionated into 

 classes by adsorption chromatography prepared according to guidelines in UNEP (1991) using 

 hexane or petroleum ether as solvent. Extracts may also be treated with concentrated sulphuric acid 

 to destroy some of the interfering lipids and then further cleaned and fractionated into classes of 

 chlorinated hydrocarbons by silica gel adsorption chromatography using known reference 

 substances for identification. 



3.2 Reagents 



All reagents, including the distilled water should be of demonstrated analytical quality. 

 Their use must result in adequate signal-to-noise ratio with the electron capture detection. All 

 reagents must be checked for their ECD response individually and by analysing complete 

 procedural blanks. If contaminants are detected the solid reagents must be cleaned by extracting 

 them with pure solvents and/or evaporating the chlorinated hydrocarbons by heating overnight at 

 260°C to 300°C. All solvents should be "distilled in glass" quality and pre-tested for their 

 suitability for pesticide analysis. The solvent should be kept in sealed ampoules (about 100 ml 

 each). Alternatively, it can be kept in Sovirel (teflon-lined caps, pyrex glass) glass bottles (200 

 ml), and kept at low and constant temperature (10°C). They may require redistillation in the 

 laboratory on a routine basis. Each bottle of solvent must be checked routinely. 



a. Demineralized distilled water produced by distillation over potassium permanganate (0.1 g 

 KMnC>4 1"1) or equivalent quality, demonstrated free from interfering substances. 



b. Ethanol, 96%. 



c. Hexane, methylene chloride acetone, iso-octane, and methanol (89°C) (all "distilled in 

 glass" quality). 



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