Synthetic corticosteroids are widely
used in live-stock breeding to treat
inflammatory diseases. The Maximum
Residue Limits (MRLs) for
dexamethasone and betamethasone in
milk, tissue, kidney and liver are
0.3, 0.75, 0.75 and 2.0 µg/kg,
respectively. For prednisolone the
MRLs are 4, 4, 6, 10 and 10 µg/kg
for muscle, fat, milk, liver and
kidney, respectively. For
methylprednisolone the MRLs are 10
µg/kg for each of the matrices
mentioned. Some corticosteroids are
permitted for use as a drug.
However, corticosteroids in general
might also be used as growth
promoter in meat production. In all
European Community countries the use
of growth promoters has been banned
since 1986. The generic
Corticosteroid-EIA is a competitive
enzyme immunoassay for the screening
of feed, milk and urine for the
presence of the following
corticosteroids (% of
cross-reactivity): flumethasone
(125%), dexamethasone (100%),
betamethasone (93%), triamcinolone
(33%), prednisolone (21%), dianabol
(7.5%) and methylprednisolone
(2.8%). The dose-response curve
shows a measuring range for
dexamethasone of 0.125-4 ng/ml. Milk
can be used directly in this test
with a sensitivity down to 0.15 ng/ml.
For feed samples, extraction methods
are described in the manual and
sensitivities down to 20 ng/g can be
obtained. Urine samples can be
applied after a dilution in buffer
or after an HPLC fractionation.
Tissue samples need a three phase
extraction and a further clean-up
procedure.