YSI 2900 series, Operation And Maintenance Manual

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8.2.10 Lactose
This is a direct reading of lactose in solution at the enzyme sensor. The enzyme Galactose oxidase is immobilized in
the enzyme membrane.
L O
2 Gal Oxidase
H
2
O
2
+ Galactose Dialdehyde Derivative
System Buffer YSI 2705
Calibrator Std YSI 2783
Linearity Std YSI 2784
Membrane YSI 2702
Membrane
Color White
Detection
Range 0.05–25 g/L
Calibration
Point 5.0 g/L
Linearity Check
Point 25.0 g/L
Sample Size
25
µ
L
End Point 30 sec
Precision
(CV,n=10) 2% or 0.02 g/L,
whichever is
greater
Linearity
±
2%
(0.05 to Cal Point)
±
5%
(Cal Point to Range
Max)
Typical Working
Life 10 days
Note: See Appendix B – Concentration
Unit Conversion if concentration unit
conversion is required.
Special Considerations:
•
If sample dilution is required, use reagent water.
•
The sample should be galactose-free. Galactose,
glycerol, and other galactosides such as raffinose and
stachyose are substrates for galactose oxidase. They
may interfere by producing artificially high lactose
readings.
•
The enzyme membrane integrity test involving the use of
YSI 2363 Potassium Ferrocyanide solution is not
informative since ferrocyanide exists in the 2705 system
buffer.