Appendix D: Analytical Methods 



a. H2 or He carrier gas at inlet pressure of 0.5 to 1.0 kg cm~2 to achieve a flow rate of 1.0 to 

 2.0 ml min'l 



b . make up gas Ar/CH* 30 ml min" 1 



c. ECD temperature 320°C (For ECD designed to be heated to that temperature only -check 

 detector manufactures specifications. CAUTION: DO NOT HEAT A 2h DETECTOR TO 

 THIS TEMPERATURE) . 



d. injector 230°C 



e. septum purge 3 ml min" 1 



f . injector purge 20 ml min" * 



g. temperature program 60°C hold 5 min the 4°C min"* to 260°C followed by a 15 min hold 

 at 260°C. A problem arises when using pentane (after HPLC clean up) as the temperature 

 programme should start well below the boiling point (i. e., 36°C). This may be difficult to 

 achieve. In this case, split/splitless injection is not recommended. Replacement of pentane by 

 hexane or heptane may be useful. 



5.4.1.9 Column test: The degree to which closely eluting CB congeners are separated by 

 the column is used as a criterion for column performance. Suitable pairs of congeners are present 

 in standards to be supplied and may be used for this purpose. 



5.4.1.10 Possible contamination effects should be checked by blank determinations 

 involving the entire procedure without using the sample. If significant ECD signals are observed, 

 the contamination problem should be traced and eliminated (e. g., re-cleaning of glassware, 

 adsorption materials, solvents, syringes, etc.). 



5.4.2 Electron Capture Detector 



The electron capture detector is an extremely sensitive tool for analysis of organochlorine 

 compounds, about five orders of magnitude more sensitive than for hydrocarbons. An equilibrium 

 concentration of thermal electrons is supplied by repeated collisions of high-energy electrons 



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