Results and discussionOptimisation of MASE procedure
Before the optimisation of MASE–SPE conditions, it was found
that rice samples became sticky under microwave heating, which
made it difficult for water steam to go through. The mixture of
the rice powder and quartz sands could avoid this phenomenon.
The recoveries of carbamate pesticides were poor when only water
steam was used as extractant, while extending the extraction time
might lead to the possible degradation of the carbamates (Prados-
Rosales, Herrera, Luque-Garcıa, & Castro, 2002). To solve the problem,
a small amount of organic solvent was added to the rice powder
in the extraction vessel before MASE. Therefore, the mixed
proportion of rice powder and quartz sands, the kind and amount
of added organic solvent were investigated first, the other conditions
were studied successively.
Results and discussionOptimisation of MASE procedure
Before the optimisation of MASE–SPE conditions, it was found
that rice samples became sticky under microwave heating, which
made it difficult for water steam to go through. The mixture of
the rice powder and quartz sands could avoid this phenomenon.
The recoveries of carbamate pesticides were poor when only water
steam was used as extractant, while extending the extraction time
might lead to the possible degradation of the carbamates (Prados-
Rosales, Herrera, Luque-Garcıa, & Castro, 2002). To solve the problem,
a small amount of organic solvent was added to the rice powder
in the extraction vessel before MASE. Therefore, the mixed
proportion of rice powder and quartz sands, the kind and amount
of added organic solvent were investigated first, the other conditions
were studied successively.
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