Weigh 1.0 g of the oil sample into a 10 mL measuring flask and add 8 mL of the solvent. Use ultra-pure solvents, free of PCB residues and with only a very low content of compounds that may influence the ECD. n-Heptane is recommended but hexane, cyclohexane and 2,2,4-trimethylpentane may be also used. Add 1 mL of the internal standard solution (2 mg/L of the congener 30 and 2 mg/L of the congener 209) and fill the flask with solvent to the indicated volume.

Conditioning: The CHROMABOND SiOH-H2SO4/SA column is mounted on top of the CHROMABOND SiOH column with the adapter (REF 730100). Suck three times 2 mL of the solvent through both columns and dry in light vacuum.

Sample application: 250 µL of the sample solution are applied on the upper column and flushed into the column with 0.5 mL solvent. The sample must be applied homogeneously on the packing of the upper column, e.g., by using a very light vacuum.

Elution: After waiting for at least 30 s the upper column is eluted two times with 1 mL of the solvent. Remove the upper column. Elute the CHROMABOND SiOH column two times with 0.5 mL of the solvent. Fill the eluate in a 5 mL measuring flask and fill the flask with solvent up to the indicated volume.