NIC Esthetician Written ExamSafety and Infection ControlMedium
An esthetician is setting up their workstation for a client. They need to prepare a disinfectant solution for their multi-use tools. The product label states a 1:10 dilution ratio with water. If the esthetician needs 1000 ml of solution, how much disinfectant concentrate should they use?
- A100 ml
- B150 ml
- C200 ml
- D50 ml
Show answer & explanationAnswer & explanation
Correct answer: A. 100 ml
A 1:10 dilution means 1 part concentrate to 10 parts total solution. If the total solution is 1000 ml, then 1000 ml / 10 parts = 100 ml per part. Therefore, 1 part concentrate is 100 ml.
Why the other options are wrong
- B. Incorrect calculation.
- C. Incorrect calculation; 1:5 ratio would yield 200 ml.
- D. Incorrect calculation; 1:20 ratio would yield 50 ml.
Disinfectant Dilution Calculation
To calculate disinfectant dilution, divide the total volume needed by the sum of the parts in the ratio (e.g., for 1:10, sum is 1+9=10, or 1 part concentrate to 9 parts water for a total of 10 parts).
- Ratio X:Y means X parts concentrate to Y parts total solution (or X parts concentrate to Y-X parts water).
- Always follow manufacturer's instructions.
- Incorrect dilution can be ineffective or damaging.
Memory trick: Total volume over total parts, finds your concentrate's starts.