Diagnosis of aluminum phosphide poisoning using a new analytical approach: forensic application to a lethal intoxication.

Aluminum phosphide (AlP) is an effective and cheap pesticide that is commonly used worldwide, but it is also a common cause of human poisoning and carries a high mortality rate. AlP reacts with moisture in air, water, and hydrochloric acid in the stomach to produce phosphine (PH3 ) gas. Two routes of exposure are ingestion of AlP and inhalation of phosphine generated by the action of moisture on AlP. Absorbed phosphine is rapidly metabolized into phosphite and hypophosphite. A method is described for the analysis of the phosphine metabolites in various biological matrices. The method involves reacting the sample with zinc and aqueous H2 SO4 in a volatile organic analysis vial. The metabolites were transformed into phosphine gas and then analyzed by headspace gas chromatography coupled with mass spectrometry (HS-GC-MS). This method is capable of detecting quantities of PH3 as low as 0.2 μg/mL in a sample. After validation, the method was applied to animal experiments and a real case of human AlP intoxication. This approach has the advantage of detecting metabolites of PH3 , in case the PH3 was converted, and can be considered a useful additional tool for the diagnosis of AlP poisoning in forensic science.