Solid-phase fluoroimmunoassay for the determination of mesotrione —a novel triketone herbicide— in water with direct measurement of the fluorescence onto the solid support

Abstract

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.

New procedures for simultaneous determination of mesotrione and atrazine in water and soil. Comparison of the degradation processes of mesotrione and atrazine

“…Mesotrione is usually detected by means of diode array detector (DAD), tandem mass spectrometry, electron Mohammadi et al 2009). Mesotrione is also determined by means of ELISA (Mastichiadis et al 2003;Strachan et al 2003) and DPC and CV (Erdogdu and Titretir 2007). Application of a new class of herbicides requires new analytical procedures for the monitoring of their levels and behavior in the environment.…”

Amperometric detection of the herbicide mesotrione based on competitive reactions at nitroreductase@layered double hydroxide bioelectrode

“…Its detection is generally possible using conventional analytical methods, namely liquid chromatography coupled with UV-Vis or fluorescence via the metabolite 2-amino-4-methylsulfonylbenzoic acid (AMBA) and mass spectrometry [2]. Sophisticated fluorometric immunosensors for mesotrione determination in water samples and in the commercial formulation (Callisto ® ) were also optimized with a limit of detection (LoD) of 0.1 nM [3,4]. A colorimetric whole cell bioassay was developed with 4hydroxyphenylpyruvate dioxygenase (HPPD) expressed in E. coli immobilized in microplates with a LoD of 69 nM [5].…”

Solid-Phase Immobilized Tripod for Fluorescent Renewable Immunoassay. A Concept for Continuous Monitoring of an Immunoassay Including a Regeneration of the Solid Phase

“…It is noteworthy that the use of fluorescein in solid-phase immunoassays is poorly described in the literature . Indeed, only a few immunoassays with direct fluorescence measurement onto the solid phase have been so far described using a microtiter plate format . Different reasons could justify this limited use.…”

“…12 Indeed, only a few immunoassays with direct fluorescence measurement onto the solid phase have been so far described using a microtiter plate format. 13 Different reasons could justify this limited use. First, fluorescein by possessing a relatively small Stokes shift of 25-30 nm and a relative broad emission spectrum presents higher background fluorescence signals compared to many other compounds, mainly due to scattering.…”