One of the most frequently used methods for determining total mercury content in biological samples is cold vapour atomic absorption spectrometry (CV-AAS), which is extensively used in the biomonitoring of environmental pollution. Seabirds are often used as bioindicators of metal contamination because of their specific feeding habits, wide geographical ranges and long lifespan.
This paper describes the validation of CV-AAS for determining the total mercury content in biological samples (whole fish, cormorant tissues). The development and optimization of the procedure is outlined, and the main objective of this study was to calculate its validation parameters. The selectivity of the method was documented; linearity (r>0.993) ranged from 0.29 to 100 ng of total mercury per sample mass. For a total Hg content of 80-1,000 ng, a polynomial calibration curve derived directly the Lambert-Beer law was used. The method showed good recoveries (average 98.0%) and a relative standard deviation for repeatability of < 10%. The limit of detection was calculated at 0.096 ng of total Hg per sample mass. The uncertainty budget was evaluated according to the 'Guide to the Expression of Uncertainty in Measurement' (GUM) [1]; the relative expanded uncertainty was estimated at < 13%.