5. CALIBRATION BY REFERENCE ENZYME MATERIALS
Certain analyzers require the use of calibrators rather than
calculation on the basis of the molar linear absorbance coef–
ficient. Provided
~hat
the reagent and rneasurernent procedures
are in accordance with these ECCLS specifications calibration
rnay be carried out using a reference enzyrne preparation, e.g.
BCR, ECCLS, NCCLS or equivalent fulfilling the perforrnance
criteria set forthese materials (23, 24, 35-37). For details
refer to ECCLS Reference Enzyrne Haterials, Draft 2, 1987
( 35) •
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
if temperature conver–
description of the
material should be
criteria, rneasurernent temperature and,
sion factors have been used, detailed
calibration procedure and calibration
given to allow cornparison.
7. WITHIN-LABORATORY IMPRECISION
This should be similar to that described for the IFCC CK Re–
ference Method (14).
8. REAGENT SPECIFICATIONS
Refer to the IFCC CK Reference Method (14).
9. RELATIONSHIP TO OTHER METHOD PRINCIPLEs
Instruments with specific instrurnent-dependent methods which
do not fall within the tolerance lirnits of this ECCLS stan–
dard Method rnay nevertheless be able to produce nurnerically
equivalent results by a calibration process. In such cases
the rnanufacturer should docurnent that the methods fulfill the
'
perforrnance criteria gi ven in 2.1 of these ECCLS standards.
The validatian of calibration of
enzy~e
rnethods is discussed
in ECCLS Reference Enzyme Materials, Draft 2, 1987 (9).
Klinisk kemi
i
Norden 2: supp/, 1990
31
