If a label reads 300 mcg/mL, how many mL are needed to prepare 0.75 mg?

To determine how many milliliters are needed to prepare 0.75 mg using a solution that is labeled as 300 mcg/mL, it is essential to first convert the mass from milligrams to micrograms, since the concentration is given in micrograms.

1. Start by converting 0.75 mg to micrograms:

• Since 1 mg equals 1000 mcg, multiply by 1000:

[

0.75 , \text{mg} \times 1000 = 750 , \text{mcg}

]

2. Now that we know we need 750 mcg, we can use the concentration of the solution to find out how many milliliters will provide this amount. The concentration is 300 mcg/mL, which means each milliliter of the solution contains 300 micrograms.

3. To find how many milliliters are necessary to obtain 750 mcg, use the following formula:

[

\text{Volume (mL)} = \frac{\text{Desired amount (mcg)}}{\text{Concentration (mcg/mL)}}

]

Substituting in the values: