Individual human sera with GT variants in clinically relevant
proportions should be used as well as appropriate certified
(ECCLS, BCR) reference enzyrne materials.
This has been studied in the case of the proposed alternative
procedure (Section 2.7) using the non-patented gamma-gluta–
myl-4-nitroanilide as the substrate. In this particular case
adequate documentation has proved the traceability to the
IFCC Reference GT Method, and the calibration procedure ensu–
res that the conditions described above are fulfilled.
o
o
2.2 Measurements at 30 C and 37 C
Refer to corresponding sections in the ECCLS standard for CK.
2.3 Temperature Conversion Factors
As discussed in the General Introduction, conversion factors
may be of use for comparison of literature data.
In evaluating such data the calibration material must be con–
sidered. As an example, in Switzerland and The Netherlands
o
o
the temperature conversion factors 37 C/37 C have been
established at 1.35 (2) and 1.28 (3a), respectively.
2.4 Concentrations of Components in the Reaction Mixture
Refer to the corresponding section for CK.
2.5 Acceptable Variation: Substrate Start
Due to the high salubility of the substrate L-gamma-gluta-
myl-3-carboxy-4-nitroanilide,
trated solution is possible.
substrate start with a concen-
The relative volumes given below have been shown to give ac–
ceptable results in practice (l-7).
80
Klinisk kemi
i
Norden 2: supp/, 1990
