At the end of last year there occurred a case of intentional incorporation of pesticide into frozen food supposedly committed by some plant worker. In this incident, helium played a role in the examination of the incorporated pesticide.

Malathion of the incorporated pesticide is a sort of organic phosphorus compound, of which testing method is regulated by the Health, Labour and Welfare Ministry as stipulated in its administrative circular titled “Testing Method of Organic Phosphorus Pesticide Residue in Foods”promulgated in March 2008. As for testing of Malathion, a gaschromatograph with flame photometric detector (GC-FPD) and a gaschromatography mass spectrometer (GC-MS) are required for use. Helium is used as a sample carrier gas for both instruments.

GC-MS is an integrated instrument of gas chromatograph and mass spectrometer. A pretreated sample is carried by helium with pressure, separated molecule by molecule with a column chromatograph and then ionized.

When the ionized molecule passes through a magnetic field of specified strength or under a high frequency wave, the passing track varies depending on the size of mass. The qualitative and quantitative analysis of sample composition is carried out by means of reading the change.