GLUCOSE BIOSENSOR - METHOD OF OPERATION

The screen display provides a menu to follow for each operation. The keys that are available for operation are shown on the right hand side of the screen display during each step.

Important keys are:

To insert a new cartridge

• Choose the Parameter option
• Q-Change cartridge? A-Y
• Enter the cartridge number.
• Enter the cartridge type G2

Follow the cleaning procedure outlined on the screen to prepare the electrode surface.

To Calibrate

• Choose the Calibrate option.
• Choose 'Calibrate with multiple standard solutions'.
• Enter concentrations and follow the cleaning and measurement procedure outlined, using first the 0.5M then the 1.0M and finally the 2.0M glucose solutions. Pipette 1ml of each solution into a 2ml vial, place into the centre hole on the stand and immerse the probe tip fully. The probe tip should be wiped clean with a tissue between measurements to prevent contamination of subsequent solutions.

The calibration procedure leads directly into the measurement procedure, allowing for the analysis of unknown solutions.

Calibration and measurement must be performed at the same temperature as we are using an enzyme reaction.

Calibration should be performed on each new cartridge and before each series of analysis.

Analysis of Potatoes

• Peel and juice potatoes.
• Allow Potato juice to settle.
• Insert sensor cartridge (See procedure above).
• Calibrate the cartridge (See procedure above).
• Check that a correlation coefficient of at least 0.990 is achieved. If this is not achieved the calibration procedure should be repeated.
• To ensure that standard conditions of pH and ionic strength are employed during both measurement and calibration, the potato juice must be added to a buffer solution. This can be completed by
  1) Accurately weighing equal masses of potato juice and 0.2M buffer solution into a vessel and taking 1ml aliquots for measurement, or
  2) Pippeting 0.5ml of potato juice and 0.5ml of 0.2M buffer into a 2ml vial.
• Prepare solutions for testing.
• Run as many analysis as are required, following the screen prompts to Dose and clean the probe tip.
• Do not leave the probe tip immersed in the test solution for longer than necessary.
• Wipe clean the probe tip with tissue between each measurement to prevent contamination of subsequent test solutions.
• When prompted for 'Dilution Factor' enter a factor of 2. This allows for the addition of buffer solution outlined above.
• The screen will display the glucose concentration in the chosen units.

To achieve the best results each test should be performed in the same routine, using a similar pressure when cleaning the probe tip.

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