RAPID AND SIMULTANEOUS ANALYSIS OF BENOMY L AND THIOPHANATE METHYL INFRUITS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A rapid and simultaneous analysis of benomyl and thiophanate methyl (T M) in fruits was developed. The compounds were extracted with a mixtur e of phosphate buffer solution (pH 6.5) and methanol (1:1) from the sa mple. A part of the extract was poured into a Chem Elut(TM) cartridge and eluted with mixture of dichloromethane and hexane (1:1). The eluat e was evaporated under reduced pressure, and the residue was dissolved in ethyl acetate. The ethyl acetate solution was poured into a Sep-pa k(R) Alumina N cartridge and eluted with methanol. The eluate was inje cted into a high performance liquid chromatograph (HPLC). Methyl-2-ben zimidazole carbamate (MBC), formed by degradation of benomyl, and TM w ere simultaneously determined by HPLC with a UV detector. The chromato graphy was performed on a TSK GEL ODS 80 TM column (4.6 mm i.d., 250 m m) with a mobile phase consisting of 0.01 M potassium dihydrogen phosp hate and methanol (1:1). Recoveries of benomyl and TM from bananas and pineapples at the level of 1 ppm were 80-87% and 73-81%, respectively . The detection limits of benomyl and TM were both 0.05 ppm.