Forensic serology: Barberio's test: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Forensic serology: Barberio's test

Sample item

A stain on a petticoat is treated with a saturated solution of picric acid, producing yellow needle-shaped crystals. Which substance is being demonstrated?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Spermine in seminal fluid (as spermine picrate)

Barberio's test uses picric acid to form yellow rhomboid or needle-shaped crystals of spermine picrate. Florence's test, by contrast, uses iodine and potassium iodide to give brown crystals of choline periodide. Both are presumptive tests for semen and neither is absolutely specific.

Option by option

  • A. Choline in seminal fluid

    Choline is shown by Florence's iodine test with brown crystals.

  • B. Urea in urine

    Urea is not the target of picric acid crystals in this context.

  • C. Spermine in seminal fluid (as spermine picrate) (correct)

    Correct. Spermine reacts with picric acid to form yellow crystals.

  • D. Haemoglobin in blood

    Haemoglobin is tested with haemin or phenolphthalein tests.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Spermine in seminal fluid (as spermine picrate). Barberio's test uses picric acid to form yellow rhomboid or needle-shaped crystals of spermine picrate.

Why is "Choline in seminal fluid" not the answer?

Choline is shown by Florence's iodine test with brown crystals.

Why is "Urea in urine" not the answer?

Urea is not the target of picric acid crystals in this context.

Why is "Haemoglobin in blood" not the answer?

Haemoglobin is tested with haemin or phenolphthalein tests.

What concept does this question test?

It tests Forensic serology: Barberio's test in Forensic Medicine. Florence's test, by contrast, uses iodine and potassium iodide to give brown crystals of choline periodide. Both are presumptive tests for semen and neither is absolutely specific.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Forensic serology: Barberio's test?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.