Immunosensor systems have been developed for the rapid
and sensitive determination of pesticides, using the
insecticide carbaryl as a model analyte. The systems
are
based on the principle of heterogeneous competitive
enzyme immunoassay and used mouse monoclonal anti-carbaryl antibodies either in solution (indirect format) or
immobilized (direct format). In both formats, enzyme
label (horseradish peroxidase, HRP) and fluorometric
detection were employed. In the direct format,
antibodies
were immobilized on a hydrazide-derivatized agarose gel,
and 6-[((1-naphthyloxy)carbonyl)amino]hexanoic
acid
(CNH hapten) conjugated to HRP was used as the enzyme
tracer. The limit of detection was 26 ng L-1 (11
min/assay), and the useful life of the sensor was 60−70
cycles.
In the indirect format, CNH conjugated to bovine
serum
albumin was immobilized on an
N-hydroxysuccinimide-derivatized agarose gel, and a rabbit anti-mouse antibody
labeled with HRP was used as a secondary immunoreagent. The limit of detection was 284 ng L-1
(17
min/assay), and the useful life of the sensor was 160−200 cycles. The developed methods were applied to the
analysis of commercial drinking water and apple juice
spiked with carbaryl. Interassay RSD ranged from 9 to
39% in the direct format and from 4 to 28% in the
indirect
format. Recoveries were between 62 and 109% in the
direct format and between 78 and 124% in the indirect
format. The results were compared with those obtained
by enzyme-linked immunosorbent assay as reference
method and indicated the suitability of the immunosensor
for quality control in water and food analysis.
Studies leading to the development of multianalyte immunosensing approaches are presented herein. Competitive capture formats are developed for carbaryl, atrazine, and irgarol 1051 as target compounds. Three proposals have been tested: sequential, additive, and simultaneous formats. For individual determinations, the best format is the sequential mode; the additive mode is useful only for qualitative analyses; and the simultaneous mode is preferable for screening purposes. The proposed systems show to be advantageous over single-analyte sensors and other multianalyte approaches. In all cases, the sensitivity reached (limit of detection) is high enough for the analysis of samples containing levels of each pesticide lower than 0.1 microg/L, and sensor reusability is very good (>600 determinations). The applicability of the multianalyte immunosensors to on-line pollution surveillance in natural waters, as well as their advantages and limitations, is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.