Analytical methods for pesticides and plant growth regulators
PESTAB. Menazon is used to control aphids on a wide variety of fruit and vegetable crops, either by soil or seed treatment or by foliar application. It is harmless to most other insect species and aphid predators. The acute oral LD50 to female rats is 1950 mg/kg; dermal LD50 is greater than 200 mg/kg. Menazon is marketed as ''Saphicol,'' which is a stable nonaqueous suspension containing 40% menazon. The recommended method for formulation analysis calls for extraction from the sample by aqueous dioxon, and passing an aliquot of the extract through a cation-exchange resin column which retains the menazon. Menazon is eluted with methanolic ammonium acetate solution and wet oxidized to orthophosphoric acid. The phosphorus content is determined as the phosphovanadomolybdate complex by differential spectrophotometry at 430 nm. For residue analysis menazon is extracted from food crops with methanol and separated from naturally occurring phosphorus-containing compounds as a cation-exchange resin column. The menazon is eluted from the resin using buffer solution and further purified by extraction into chloroform. The chloroform is evaporated and the residual menazon wet oxidized to inorganic phosphate and determined as the deep blue molybdophosphate complex at 820 nm. Recovery of added menazon from 50 gm samples of food crops are listed for brussels sprouts, potatotes, sugar beets, sugar beet foliage, apples, broad beans, cabbage, and strawberries. The detection limits were about 0.05 ppm on a 50 gm sample. The detection methods have been successful on other crops such as lettuce, black currants, gooseberries, carrots, Kaffier corn, tobacco, and soil.