Barberio Reaction

BARBERIO REACTION (Barberio), used in forensic medicine for detecting the presence of semen in suspicious stains on clothing as evidence in accusations of rape and molestation. The first microchemical reaction for semen was published in 1896 by Florence, but research did not confirm the specificity of this reaction, proving that other fluids containing choline (infusions of human brain and liver, horse semen, etc.) also give the Florence reaction. In 1905, Barberio proposed using a saturated aqueous or alcoholic solution of picric acid for this purpose, which with human semen or its extract forms numerous yellow needle-like crystals, 1-1^g/₂ the size of a sperm head, sometimes much smaller (but it sometimes happens that more or less definite crystalline formations are not observed). The crystals appear as oval bodies; more or less elongated or rounded; sometimes they cross each other, more rarely forming a star. Features of this reaction: the stability of the crystals and their formation from a negligible amount of material; with no organic fluid except human semen and Pelle's spermine, according to Barberio himself, the reaction is obtained, which was confirmed by Modi-ea, Chevidalli, and Bokarius. Performing this reaction requires great skill: an excess of reagent or excessive dilution of the extract gives a negative result. Bokarius for better results recommends the following mixture: Acidi acetici glacialis, Aquae dest. 35, Acidi picronitrici q. s. ad saturationem. The B. r. is still not absolutely specific for human semen (the finding of spermatozoa is necessary), which, however, does not deprive it of great interest from the point of view of forensic-medical practice.