YSI 1500 Sport, User Manual, Page: 36 / 134

5 5 5 5----2 2 2 2
Reaction 1 (lactate):
L O
2 LOx
Py H
2
O
2
Reaction 2: H
2
O
2 Pt anode
2H
+
+ O
2
+ 2e
-
The platinum electrode is held at an anodic potential and is capable of oxidizing
many substances other than H
2
O
2
. To prevent these reducing agents from
contributing to sensor current, the membrane contains an inner layer consisting
of a very thin film of cellulose acetate. This film readily passes H
2
O
2
but
excludes chemical compounds with molecular weights above approximately
200. The cellulose acetate film also protects the platinum surface from proteins,
detergents and other substances that could foul it. However, the cellulose acetate
film can be penetrated by such compounds as hydrogen sulfide, low molecular
weight mercaptans, hydroxylamines, hydrazines, phenols and anilines.
Certain detergents, endogenous and exogenous substances, preservatives and
reducing agents can interfere with the SPORT sensor system, resulting in
erroneous readings. (See Appendix E–Effects Of Selected Substances).