The invention discloses a method for detecting residual
methidathion in a ripe orange. The method for detecting residual
methidathion in the ripe orange comprises the following steps: (1) dividing a ripe orange into an orange peel part and a pulp part,
cutting the orange peel into pieces, and squeezing pulp with a juice extractor to obtain juice for later use; (2) respectively putting the orange peel and pulp into conical flasks, respectively adding
acetonitrile water mixed liquor, and carrying out vibrating extraction for 50-70 minutes; respectively carrying out suction
filtration to obtain clear liquids; concentrating the clear liquids respectively, and realizing constant volume being 10ml again by adopting water, so as to obtain an orange peel sample and a pulp sample for later use; (3) putting neutral
aluminium oxide powder into a
muffle furnace, activating for 4 hours at the temperature of 680 DEG C, packing, firstly passing a column with 20ml
acetonitrile, loading the samples, firstly activating a small column with 10ml mixed liquor of
acetonitrile and water in a volume ratio of 1:1, then leaching with 20ml acetonitrile, collecting leacheate, carrying out rotary
evaporation until volume of the leacheate is 1ml, blow-
drying with
nitrogen, realizing constant volume being 5ml by adopting
acetone, and making preparation for detection; (4) detecting by adopting a
gas chromatography.