Determination of 210Pb and 210Po in water using the extractive scintillation cocktail Polex™

• With this method Pb-210 and Po-210 can be determined with one measurement.
• Matrix interferences causing extraction problems are eliminated by washing with 1% HNO3.
• The chemical recovery of the lead can be used to calculate the Po-210 activity concentration.
• Uranium which can be extracted by Polex™ is removed washing the precipitate with 1% HNO3.

Method validation was performed to achieve the accreditation for our determination method of 210Pb and 210Po in water. A Pb(NO3)2 carrier is added to the sample and lead is precipitated with Na2SxH2O. 210Po is co-precipitated and the extractive scintillation cocktail Polex™ is used to determine 210Po and 210Pb. Uranium is also extracted by Polex™. It can be removed by washing the precipitate with 1% HNO3. The ingrowth of 210Pb from 222Rn during transportation time must be calculated. It has to be subtracted from the original 210Pb in the sample and taken into account for the calculation of the lower limit of detection.