Tannin and gallic acid as marker of exposure to hardwood dust]

The total tannin concentration was determined, using two different SPF methods, in 35 dust powdered wood species, both hard and softwood. Using direct reading-method (280 nm) the concentration varied from 2485 mg/g for Swedish pine to 35,843 mg/g for European oak (quercus robur, hardwood). The data obtained with the second method (Folin-Chocalteau) were well correlated (y = 0.9885x + 4.3373; r = 0.84; n=35) with the data obtained with the first method. The measured concentrations are usually higher in hardwood than softwood tested. Finally, a simple HPLC-DAD method was tested for gallic acid (GA), recently proposed as a marker for oak dust.