PTCB Certified Pharmacy Technician (PTCE)MedicationsMedium
A pharmacy technician is preparing a non-sterile compound. The formula requires 0.5 mL of a liquid ingredient. Which of the following measuring devices would provide the MOST accurate measurement for this volume?
- AA 100 mL graduated cylinder
- BA 50 mL conical graduate
- CA 1 mL tuberculin syringe
- DA 10 mL oral syringe
Show answer & explanationAnswer & explanation
Correct answer: C. A 1 mL tuberculin syringe
For measuring small liquid volumes (less than 1 mL), a tuberculin syringe provides the highest accuracy. Graduated cylinders and conical graduates are less accurate for very small volumes, and a 10 mL oral syringe, while better than larger graduates, is still less precise than a 1 mL tuberculin syringe for 0.5 mL.
Why the other options are wrong
- A. A 100 mL graduated cylinder is far too large for accurate measurement of 0.5 mL.
- B. A 50 mL conical graduate is not precise enough for such a small volume.
- D. A 10 mL oral syringe is better than larger graduates but less accurate for 0.5 mL than a 1 mL syringe.
Measuring Small Liquid Volumes
The principle of selecting the smallest appropriate measuring device that can accurately measure a given liquid volume, typically using syringes for volumes less than 1 mL.
- Use smallest device for accuracy.
- Syringes are most accurate for small volumes.
- Graduated cylinders/conical graduates for larger volumes.
Memory trick: Small Volume, Small Syringe, Super Accurate.