Stock glucose standard, 100 mmol/l
1. Weigh accurately 1.8 g of dry anhydrous glucose (analytical reagent grade).
Note: To ensure the glucose is dry, heat it in an open container in an oven at 60–80 °C for about 4 hours. Remove and close the container immediately. When cool, weigh the glucose.
2. Transfer the glucose to a 100 ml volumetric flask.
Half fill the flask with 1 g/l benzoic acid and mix until the glucose is fully dissolved. Make up to the 100 ml mark with the
benzoic acid reagent and mix well.
The glucose concentration in the flask is 100 mmol/l.
3. Transfer to a storage bottle and label. When stored at 2–8 °C the stock standard is stable for about 6 months. If stored frozen in tightly stoppered containers the stock standard is stable for at least 1 year.
Working Standards
1. Take five 100 ml volumetric flasks and number them 1 to 5. Pipette accurately into each flask as follows:
Flask Stock glucose, 100 mmol/l
1 ………………………………………. 2.5 ml
2 ………………………………………. 5.0 ml
3 ………………………………………. 10.0 ml
4 ……………………………………… 20.0 ml
5 ……………………………………… 25.0 ml
2. Make the contents of each flask up to the 100 ml mark with 1 g/l benzoic acid and mix well.
The concentration of glucose in each standard is as follows:
Flask
1 = 2.5 mmol/l
2 = 5.0 mmol/l
3 = 10.0 mmol/l
4 = 20.0 mmol/l
5 = 25.0 mmol/l
3. Transfer each solution to a storage bottle and label. Store at room temperature (20–28 °C).
The working standards are stable for about 2 months
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