Wavelengths, pathlengths, final volume of reaction mixture:
Instrument dependent, see below. 340 nm has been used consis–
tently in this description.
o
o
Reaction temperature: Strictly controlled at 37 C or 30 C
with a maximal allowed deviation of± 0.1 °C (Cf ref. 20,
CK).
1.2 Specimen
Serum is the preferred specimen.
2. ACCEPTABLE VARIATIONs FROM ECCLS MEASUREMENT PROCEDURE
2.1 Performance specifications
Deviations from the above measurement procedure may endanger
the robustness of the method and should be kept as small as
possible. However, for adaptation to routine use with diffe–
rent types of analyzers acceptable variations for sample and
reagent volume fractions, component concentrations, substrate
and serum start, activation, lag-phase, and measurement times
will be described below.
Any changes in the reaction system must be documented by
their proposers. The average total deviation of results must
be less than 5% from those obtained with the IFCC ALAT Refe–
rence Method at the same temperature. This should be shown
for sera with catalytic activity concentrations close to the
upper reference limit and also for samples with elevated ac–
tivities up to the limit of linearity of the method.
Individual human sera with ALAT isoenzywes in clinically re–
levant proportions should be used
~s
well as appropriate cer–
tified (NBS, ECCLS, BCR) reference enzyme material. Evidence
on the performance of the proposed methological change should
include the effect on sample and reagent blank rates.
Klinisk kemi
i
Norden 2: supp/, 1990
61
