Lead Toxicity in Mute Swans

human pool was used to account for the matrix effect of blood; pooled
swan blood was not used because it gave excessively high readings.
Lead estimations were carried out on a PYE Unicam SP192 atomic
absorption spectrophotometer with a flameless atomiser attachment, and
at a wavelength of 217nm.
Estimations were carried out at least twice.
If the range of duplicates exceeded 10% of the mean, further aliquots
were analysed.
Appropriate dilutions were made if specimen values
exceeded those of the standards.
Lead concentrations were calculated by
reading directly from a standard curve or calculated using the
regression equation from the line of best fit.
Control specimens of human blood (from Guilford, U.K.), with known
consensus mean values, were run every third swan specimen to ensure
stability of the instrument.
Haemoglobin analyses.
Haemoglobin concentration and haematocrit (packed cell volume) were
estimated for all blood samples.
Haemoglobin concentration was
estimated by converting all haem species to alkaline haematin using a
non-ionic detergent.
20ul of fresh, well mixed whole blood was added to
3ml of a solution of 25g scintillation grade Triton X 100 in 1 litre of
0.1 molar NaOH (see O'Halloran et al., 1987b). Three replicates were
made and read in a spectrophotometer at 575nm.
The haemoglobin
concentration was calculated from a standard curve, prepared from pure
alkaline haematin (99% pure from Serva, Heidelberg, FRG).
Packed cell
volume was estimated by spinning three replicates of each sample in a
Hawksley microcentrifuge at 12,000 x g (determined stroboscopically) for
30 mins and values of haematocrit calculated.
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