Division 5.1 Low working range and limits of quantification

For PCDD/Fs, detectable quantities have to be in the upper femtogram (10^{– 15} g) range because of extreme toxicity of some of these compounds. For most PCB congeners limit of quantification in the nanogram (10^{– 9} g) range is already sufficient. However, for the measurement of the more toxic dioxin-like PCB congeners (in particular non-ortho-substituted congeners) the lower end of the working range must reach the low picogram (10^{– 12} g) levels.