5. CALIBRATION BY REFERENCE ENZYME MATERIALS
For details refer to the corresponding seetian and references
in the ECCLS standard for CK, above. A certified ASAT refe–
rence material from human erythrocytes has recently been pro–
duced (21).
6. REFERENCE VALUES
Provided this standard is followed the variability of refe–
rence values should depend only on the individuals selected
in different studies. Therefore, the population selection
criteria, measurement temperature and, if temperature conver–
sion factors have been used, detailed description of the ca–
libration procedure and calibration material should be given
to allow comparison.
7. WITHIN-LABORATORY IMPRECISION
This should be similar to that described for the IFCC ASAT
Reference Method (l).
8. REAGENT SPECIFICATIONS
Refer to the IFCC ASAT Reference Method (l).
9. RELATIONSHIP TO OTHER METHOD PRINCIPLES
Instruments with specific instrument-dependent methods which
do not fall within the tolerance limits of this ECCLS stan–
dard Method may nevertheless be able to produce numerically
equivalent results by a calibration process. In such cases
the manufacturer should document that the methods fulfill
the performance criteria given in 2.1 of these ECCLS stan–
dar d s. The validatian of calibration of enzyme methods is
dis cussed in ECCLS Refe r ence Enzyme Materials, Draft 2, 1987
(9). It is not possible torelate methods without pyridoxal-
5'-phosphate activation to the ECCLS standards for ASAT and
ALAT.
Klinisk kemi
i
Norden 2: supp/, 1990
53
