INTERNATIONAL FEDERATION OF CLINICAL
CHEMISTRY
AND LABORATORY MEDICINE
SCIENTIFIC DIVISION
COMMITTEE ON NOMENCLATURE,PROPERTIES,AND UNITS*
and
INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY
CHEMISTRY AND HUMAN HEALTH
DIVISION
COMMISSION ON NOMENCLATURE,PROPERTIES,AND UNITS*
Unit "katal" for catalytic activity (IUPAC Technical Report)
R. Dybkaer
Department of Standardization in Laboratory Medicine,
H:S Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Frederiksberg,
Denmark
Abstract: Expressing the amount of a catalyst is often most
conveniently done by assessing its catalytic effect. Under zero-order
kinetics the catalyzed rate of conversion for a specified reaction is
constant and proportionate to the amount-of-substance concentration
of catalyst present. Defining the kind-of-quantity "catalytic activity"
as a property of the catalyst measured by the catalyzed rate of conversion,
the coherent SI unit is mole per second. Following thorough discussions
in the IUPAC, the International Federation of Clinical Chemistry and
Laboratory Medicine (IFCC), the International Union of Biochemistry
and Molecular Biology (IUBMB), and the World Health Organization (WHO),
a petition was presented by the IFCC to the International Committee
for Weights and Measures (CIPM) on a special name "katal",
symbol kat, for "mole per second" when used in measuring catalytic
activity. This request was granted by the General Conference for Weights
and Measures (CGPM) by Resolution 12 (1999). Hereafter, the coherent
SI unit katal = 1 mol s1 should replace the off-system IUB unit
"(enzyme) unit" = 1 mmol min1 16.67 nkat. Thus, by suitable
definition of reaction conditions, results for catalytic activity and
derivative kinds-of-quantity are metrologically traceable to the SI.
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