Alcohol Facts by National Draeger
The easiest way for a technician to prepare Simulator working and stock solutions is by first acquiring a number of laboratory materials:
500 milliliter volumetric flask
1000 milliliter volumetric flask
10 milliliter graduated pipette
75 milliliter pipette
2 milliliter volumetric pipette
Approximately 80 milliliters of absolute ethyl alcohol
The first solution to be prepared is called a "Stock" solution. This solution is so named because it is the basis for preparations of the working solutions. With the following calculations it is extremely easy to prepare working solutions after the initial stock solution has been prepared.
Preparing A Simulator Stock Solution
Take one liter volumetric flask and add 100 ml of distilled water. Rinse the flask, drain and repeat this procedure at least once more. Once the flask is clean, add approximately 500 ml of distilled water to the flask. Fill a 75 ml volumetric pipette with absolute alcohol so that the bottom of the meniscus is just above the volume line of the pipette. Once the pipette is filled, allow it to drain into the flask. Pipette 2 ml of ethyl alcohol into one liter flask. After this is completed, you have added 77 ml of absolute alcohol, finish filling the flask with distilled water so that the meniscus of the solution in the flask is just above the volume line. Stopper the flask and invert it 3 or 5 times to assure a proper solution mixture. Always be sure to label the flask "STOCK".
Briefly, what we have done is half filled a 1 liter volumetric flask, introduced 77 milliliters of absolute alcohol to that, and then brought the total volume up to 1 liter.
Preparing a Simulator Working Solution
To prepare a working solution, rinse a 500 ml volumetric flask using the same procedures we discussed for the stock solution. After rinsing, half fill the flask with distilled water. Add one milliliter of stock solution for each 0.01% desired. After adding the proper amount of stock solution, finish filling the flask with distilled water so the meniscus is just above the volume line on the flask. Invert 3 or 4 times to assure proper mixture. Be sure to label the flask with the proper solution concentration.
