Dioxin and polychlorinated biphenyl analysis: Automation and improvement of clean‐up established by example of spices

To analyze polychlorinated dibenzo‐ p ‐dioxins/dibenzofurans (PCDDs/PCDFs) and polychlorinated biphenyls (PCBs) in spices by gas chromatography‐mass spectrometry, a new clean‐up method had to be developed owing to the high content of essential oils in the samples. A solid‐phase extraction (SPE) column with activated silica endowed with sulfuric acid and sodium hydroxide was used. Under these conditions, clean‐up was achieved using at least 5–7 g of pepper and even higher amounts of other spices. The automatized clean‐up comprised three additional chromatographic steps after accelerated solvent extraction (ASE) followed by gel permeation: chromatography on a florisil SPE column, extract cleaning with the above‐mentioned silica SPE column and chromatography with an activated charcoal column. On the basis of this automatized clean‐up, a method that is more effective, rapid, simplified and economical than the available methods for PCDD/PCDF and PCB analysis is proposed. In model studies, the average recoveries for PCDDs/PCDFs ranged between 82.6% and 105.6% and for the PCBs between 71.3% and 113.3%.