During a test for metallic salts, how long should the hair strand be immersed in the hydrogen peroxide and ammonia solution?

• A. 15 minutes
• B. 30 minutes
• C. 60 minutes
• D. 90 minutes

Answer: (B)

The test relies on diffusion of metallic salts from the hair into the testing solution, which requires opening the hair cuticle and creating conditions that let ions move out of the strand. Using hydrogen peroxide with ammonia creates an oxidizing and alkaline environment that lifts the cuticle so metals can be released into solution.

Thirty minutes provides enough time for the salts to diffuse and be detectable, without over-processing the hair. Shorter times, like fifteen minutes, may not extract enough metal ions for a reliable result. Longer times, such as sixty or ninety minutes, can over-oxidize or damage the hair matrix and potentially alter the metals, leading to unreliable outcomes.

So, immersion for about thirty minutes balances effective extraction with preserving the sample and accuracy.