4-14
##-+!
This is a direct reading of L-glutamate in solution at the enzyme sensor. The enzyme L-Gluta-
mate Oxidase is immobilized in the YSI Glutamate Membrane.
L-Glutamate + O
2
Glut Oxidase
H
2
O
2
+ α-Ketoglutarate + NH
3
System Buffer YSI 2357
Calibrator Std YSI 2755 (5.00 mmol/L glutamate)
Linearity Std YSI 2756 (10.00 mmol/L glutamate)
Black Probe YSI 2754 (Glutamate Oxidase Membrane)
White Probe n/a *
Sample Size 25 µL
Cal Station Station #1 Cal Well
Black Probe Parameters
Chemistry Glutamate
Unit of Conc mmol/L
Cal value 5.00
End Point 30 sec
* 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:
»
If sample dilution is required, use reagent water or 2357 Buffer.
»
If you want to measure MSG (monosodium glutamate, monohydrate) and express the
results as mmol/L of MSG, the calibration parameters listed above are all appropriate.
If you want to express results as a w/v measurement, such as mg/L MSG, then
correction for the sodium and water components is necessary.
To express results as an MSG value, change the glutamate units to a w/v expression,
and enter one of the following: 936 mg/L, 0.936 g/L, or 0.094 %. Use YSI 2755
Calibrator Standard (5.00 mmol/L Glutamate) to calibrate the instrument. Sample
results will then reflect MSG concentration.
Potential Interferences. Tests with equimolar concentrations of other amino acids and related
substances showed little or no interference. On a scale where Glutamate = 100%, those
substances that produced more than 0.5% response were L-Aspartate (0.7), L-Tyrosine (1.4), L-
Histidine (0.7), and L-Glutamine (1.1). Glutamate cannot be ruled out as a contaminant in the
Glutamine solution.
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