Final answer:
To find the amount of vasoconstrictor in a 1.8 mL dental cartridge of 2% lidocaine with epinephrine 1/100,000, the concentration per mL is 0.01 mg/mL. Multiplying by the cartridge volume gives 0.018 mg of epinephrine, so the correct answer is B. 0.018 mg.
Step-by-step explanation:
When calculating the amount of vasoconstrictor in a dental cartridge of lidocaine with epinephrine, you need to understand the concentration notation and how to apply it to the volume of the solution. A concentration of 1/100,000 means that there is 1 gram of substance in 100,000 milliliters (mL) of solution. Therefore, in a 1.8 mL dental cartridge:
- Determine the amount of epinephrine per mL by dividing the mass of epinephrine (1 gram) by the volume of the solution it's in (100,000 mL): 1 g / 100,000 mL = 0.00001 g/mL.
- Since 1 g is equal to 1,000 mg, converting into milligrams gives us: 0.00001 g/mL * 1,000 mg/g = 0.01 mg/mL.
- Multiply this concentration by the volume of the cartridge (1.8 mL) to get the total amount of epinephrine in the cartridge: 0.01 mg/mL * 1.8 mL = 0.018 mg.
Therefore, the correct answer is B. 0.018 mg of vasoconstrictor in a standard dental cartridge containing 2% lidocaine with epinephrine 1/100,000.