YSI 2700 SELECT - Hydrogen Peroxide

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 *+, +
This is a direct electrochemical reading of hydrogen peroxide at the enzyme probe. A structure
similar in appearance to an enzyme membrane is used at the probe surface. This membrane
contains immobilized nonenzymatic protein to produce diffusion properties similar to those
exhibited by YSI Enzyme Membranes.
The electrochemical reaction, which is common to all YSI Enzyme Sensors, is the following:
H
2
O
2
Platinum anode
2H
+
+ O
2
+ 2e
-
System Buffer YSI 2357 (see note below regarding catalase)
Calibrator Std n/a *
Linearity Std n/a *
Black Probe YSI 270l Blank Membrane
White Probe n/a**
Sample Size 25 µL
Cal Station Station #2 Test Tube Holder
Black Probe Parameters
Chemistry Peroxide
Unit of Conc mg/L
Cal value user's choice (recommend about 30 mg/L)
End Point 30 sec
* YSI does not currently offer hydrogen peroxide standard solutions.
** If you have a dual channel unit, either Black or White, or both Black and White probes can
be configured for this chemistry.
Note: See Appendix A if concentration unit conversion is required.
Special Considerations:
»
Since hydrogen peroxide is typically used to calibrate the YSI Blank Membrane, the
enzyme
catalase
is a concern. Catalase destroys hydrogen peroxide. Catalase occurs
naturally and may be in the sample you are testing. If so, it can also accumulate in the
2700 SELECT sample chamber. A small amount of sodium azide added to the system
buffer will inactivate the catalase. Concentrations around 5 mg/L sodium azide are
appropriate.
»
If you have a dual channel 2700 SELECT and suspect an electrochemical interference
(as opposed to an enzymatic interference), you may want to use one channel to
qualitatively
monitor for an interference effect.
Typical electrochemical interferences include phenols, mercaptans, hydroxylamine, hydrazine
and analines. If you suspect a particular substance, you may want to configure one of your
probes with a blank membrane and calibrate it as described above under Hydrogen Peroxide.
Then run your sample and check for activity at the Blank Membrane. It is not quantitative, but
may provide useful information about your sample.