Quality control strategies at the environmental specimen bank of the federal pepublic of germany

摘要

Stringent quality control (QC) and harmonization of sampling protocols are fundamental requirements for long term environmental monitoring as it has been carried out at the Environmental Specimen Bank (ESB) of the Federal Republic of Germany for mor ethan 15 years. Reliable data for legislation and recommendations need to be of the highest quality both from the analytical as well as the acquisition points of view. Quality assurance measures, thus, should always start at the sampling site where errors due to the wrong specimen, contamination or loss, wrong containters or biodegradation can influence the final result fundamentally. At the ESB, specially designed sampling protocols have been develoed to minimize such unwanted influences. To ensure a maximum of sample integrity the materials are deep frozen at the site of sampling and processed under liquid nitrogen temperatures so that the finally analysed aliquot in the laboratory represents well the particular sector of the environment itended to be studied. The samples are taken in large quantities (2.5 kg). stored in the vapour phase of liquid nitrogen (<-150 deg C) at the place of sampling, transported to the laboratory cryogenically, ground, homogenized and made into aliquots (5-10 g fresh) cryogenically and stored 'deep cool' until use. Analytical quality control comprises the use of in-house (matrix identical) reference materials (RMs), analysis of certified RMs, intermethod comparison and participation in interlaboratory comparison exercises, as well as participation in certification campaigns for can didate RMs from international and national organizations. The final data set is checked for outliers and typing errors by experienced personnel before it is released to the general public. Only if consensus in replicate measurements with more than one technique is found (within the limits of uncertain) can those values can be regarded as being representative, accurate and reliable.