A mixture stock solution containing metolcarb, carbofuran,
baygon, isoprocarb and methiocarb (each at 100 μg mL - 1) was prepared in methanol and stored
in a brown volumetric flask at
4 °C. A series of working solutions were freshly prepared by mix- ing an appropriate amount of
the stock solution with ultrapure
water to obtain the desired concentrations.