I'm assuming you meant 0.2 mg, not 0.02 mg -- 0.02mg would be an extremely small sema dose. The amount of sema in the vial and the dosage you want are two different things.
The tricky part is diluting the sema with bacteriostatic water, and deciding how much water to add. Once you have all these values, you can figure out the correct amount to draw into a syringe.
Arithmetic is your friend! It looks complicated at first, but I suggest you research the process so you can verify the calculator's results. A calculator is a tool, not a substitute for understanding. Blindly trusting it can lead to errors.
Here's my approach:
First, calculate the mg per mL of the vial. This is the concentration.
For instance, if you add 2 mL of bacteriostatic water to a 5 mg vial, the concentration is 2.5 mg/mL. This vial would contain 25 doses of 0.2 mg (5 mg / 0.2 mg/dose).
Next, figure out the syringe volume:
Divide the desired DOSE (in mg) by the VIAL concentration (in mg/mL).
0.2 mg / 2.5 mg/mL = 0.08 mL
To verify, 0.08 mL is 1/25th of 2 mL, which is correct since the vial has 25 doses of 0.2 mg.
Finally, convert mL to units. One unit equals 1/100 mL. Syringes use units for easier readings. So, 0.08 mL * 100 = 8 units. Don't mix these up!
Run these calculations with your specific values.
Also, consider the amount in the vial. Check the CoA -- you have one, right? Use the average weight as the true amount. For example, if a 10 mL vial tests at 11.4, 11.3, and 11.4 mg, the average is 11.4 mg.
Last, check that the syringe volume is reasonable. If you're using 100-unit (1 mL) syringes, 8 units will be hard to measure. Smaller syringes (30, 50, or 100 units) have more distinct marks. You can also add more BAC to the vial for a larger shot volume. 2 mL is standard, but you can go up to 2.5 mL. Adjust this amount to make measuring the volume easier.
