The Detection of Iron Traces on Hands by Ferrozine Sprays: A Report on the Sensitivity and Interference of the Method and Recommended Procedure in Forensic Science Investigation

Spectrophotometric studies and controlled laboratory tests showed that ferrozine alone is inefficient in revealing iron traces on hands. However, when a reducing agent capable of converting Fe(III) to Fe(II) is used in conjunction with the ferrozine spray, the sensitivity of the detection is greatly enhanced. Several reducing agents including sulfite, hydroxylamine hydrochloride, thioglycollic acid, and ascorbic acid were studied, and ascorbic acid was found to be the best choice in terms of the reduction efficiency and nontoxicity. The effects of copper, zinc, nickel, aluminum, tin, lead, and chromium on the detection of iron by ferrozine with and without the reducing agents were studied, and ways to remove the interference or to interpret the results in the presence of interference are suggested. Finally, a procedure is outlined for spraying hands and gloves with a ferrozine-ascorbic acid mixture and deducing from the revealed iron traces the kinds of metal objects with which they have been in contact. A procedure is also outlined for transferring iron traces from hands onto filter paper for those persons who refuse to have their hands sprayed with chemicals like ferrozine whose toxicity is unknown.