Abstract:
Zinc phospide (Zn3P2) and aluminum phosphide (AlP) are well known rodenticides
which are used to control insects and rodents especially at grain storages. In the
aqueous or acidic medium metal phosphides releases phosphine gas (PH3) which is
harmful to rodents, who do not have a vomiting reflex. Exposure of higher
concentrations of PH3 can be harmful to domestic animals and even human life. The
AgNO3 test was conducted to acquire a draft idea about the presence of metal
phosphide in the samples. For the analytical purpose, samples were hydrolyzed with
aqueous sulphuric acid inside a gas chromatography-headspace (GC-HS) vial. Toluene
was used to trap the released PH3 and the vials were roller mixed to get a better
extraction. The toluene layer was separated and inspected by gas
chromatography–nitrogen phosphorous detector (GC-NPD). Metal identification of the
chemical compound was done using inductively coupled plasma mass spectrometer
(ICP-MS). Only one sample out of five tested samples showed positive contamination
with metal phosphide. The ICP-MS results confirmed the presence of AlP in the
suspected chemical compound. This method could be used to identify metal phosphide
contamination in agricultural commodities like rice, dhal, coriander and other grains.
