Solid-phase fluoroimmunoassay for the determination of mesotrione--a novel triketone herbicide--in water with direct measurement of the fluorescence onto the solid support.
A straightforward, low-cost fluoroimmunoassay (FIA) for the determination of the new triketone herbicide mesotrione has been developed and optimized. The protein-mesotrione conjugate, immobilized on white opaque microtitration wells competes with the mesotrione in the sample or standard for the limited binding sites of a liquid phase anti-mesotrione antibody. The assay is based on the measurement of fluorescence intensity directly onto the solid support, using a fluorescein labeled second antibody and a fluorescence plate reader. To stabilize and enhance the fluorescence signal a glycerine-based treatment of the microtitration wells was included in the protocol. The detection limit of the assay is 40 ng 1(-1) (4 pg per well), the working range extends up to 9 microg l(-1), whereas the within and between run CVs are 0.7-4.2% and 2.1-5.5%, respectively. To evaluate the assay specificity, the cross-reactivities of two mesotrione metabolites: 4-methylsulfonyl-2-nitrobenzoic acid and 2-amino-4-methylsulfonyl-benzoic acid and several other compounds similar in structure to mesotrione such as: fomesafen, prosulfocarb, fluazinam, sulcotrione, 1,2-cyclohexanedione, 1,3-cyclohexanedione, 2-acetyl-1,3-cyclohexanedione were assessed. Most of the substances tested presented very low ( < 0.05%) cross-reactivity values with the exception of sulcotrione that cross-reacted 23% in the mesotrione assay. The assay was used for the determination of mesotrione in bottled natural waters fortified with the analyte and in a commercial herbicide formulation, namely CALLISTO.
Mastichiadis
Christos
C
Institute of Radioisotopes and Radiodiagnostic Products, Immunoassay Laboratory, NCSR "Demokritos", Aghia Paraskevi, 15310 Athens, Greece.
Christofidis
Ion
I
Koupparis
Michael A
MA
Willetts
Caroline
C
Kakabakos
Sotiris E
SE
D000818:Animals; D003512:Cyclohexanones / Q000032:analysis*; D015200:Fluoroimmunoassay / Q000379:methods; D006540:Herbicides / Q000032:analysis*; D007106:Immune Sera / Q000302:isolation & purification; D011817:Rabbits; D014874:Water Pollutants, Chemical / Q000032:analysis*
D003512:Cyclohexanones; D006540:Herbicides; D007106:Immune Sera; D014874:Water Pollutants, Chemical; C432907:mesotrione