A patient with suspected arsenic poisoning undergoes Reinsch test. A bright silvery metallic deposit appears on the copper strip. To distinguish arsenic from antimony in this deposit, the next confirmatory step is:
- A Marsh test — arsenic generates arsine gas that forms mirror on glass
- B Boiling the strip in HCl — arsenic dissolves while antimony remains ✓
- C Atomic absorption spectrophotometry (AAS)
- D Gutzeit test — arsenic forms yellow stain on mercuric chloride paper
Correct answer: B. Boiling the strip in HCl — arsenic dissolves while antimony remains
Explanation
On the Reinsch test both arsenic and antimony give a silvery-grey metallic deposit on copper. Differentiation is done by treating the strip with concentrated HCl: arsenic dissolves readily (arsenic trichloride is formed) whereas antimony is insoluble in HCl. The Marsh test is highly sensitive and quantitative but is a separate test system; AAS is definitive gold standard but not the classical chemical differentiation used in this context.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
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Written and medically reviewed by the StethoPrep medical team.