406
A. Roda . P. Pasini . M. Guardigli
analysis of both freshwater and sea water samples, since the salt content of the sea water
did not interfere in the assay (Roda et al. 1991). Instead, a preliminary desalting procedure was necessary if the sea water sample was preconcentrated before analysis.
A time-resolved fluoroimmunoassay was developed for the detection of benzo(a)pyrene (Ius et al. 1992) on the basis of the previously reported work. This direct heterogeneous immunoassay was developed using a specific antibody labelled with an
isothiocyanatophenyl-EDTA-Eu complex. After the immunoreaction, the lanthanide
complex was dissociated, and the amount of metal ion in solution was determined via
a time-resolved fluorescence measurement upon addition of an enhancement solution forming a luminescent europium complex. The detection limit (about 0.5 ng rnI- 1 )
was low enough for the application of the method on water samples without preliminary extraction or concentration procedures. Phthalate esters, widely used as plastifiers,
were determined in a direct competitive immunoassay based on a time-resolved fluorescence measurement using rabbit antibodies against phthalate esters (Ius et al.1993).
The bound antibodies were detected using a biotinylated anti-rabbit antibody and a
BCPDA-Iabelled streptavidin. Metal luminescence intensity was then measured in the
time-resolved mode upon addition of an excess of europium ion. This assay was able
to detect as low as 0.5 pmol mrl of the most diffused phthalate esters.
A chemiluminescent flow sensor was developed for the determination of organophosphorus (Paraoxon) and carbamate (Aldicarb) pesticides in water (Roda et al.1994).
The flow sensor relies on the inhibition of acetylcholinesterase (either in solution or
immobilized on a solid support) due to pesticides. A series of coupled enzymatic reactions, catalysed by the enzymes choline oxidase and peroxidase immobilized on a
solid support, was used in order to allow the chemiluminescent measurement of the
acetylcholinesterase activity. Detection limits of 0.75 flg rl and 4 flg rl were reported
for Paraoxon and Aldicarb, respectively.
The water sample content of the herbicide chlortoluron was determined using an
enhanced chemiluminescent immunoassay (Kameth et al. 1996) in which the chemiluminescence signal was detected by means of a camera luminometer, providing a
semiquantitative assay based on a photographic record of the luminescent end point.
This assay could represent a rapid, simple and portable means of monitoring multiple
water samples for the presence of chlortoluron or other pesticides. In the reported
example, the assay was able to identify and quantitate the herbicide with good accuracy at or above the European limit for individual pesticides in drinking water.
Detection of atrazine in water was also performed by means of an electrochemiluminescence flow injection immunoassay based on anti-atrazine antibodies labelled
with glucose oxidase (Wilson et al. 1997). This competitive electrochemiluminescent
immunoassay used transparent aminosilanized indium tin oxide-coated glass electrodes, derivatized with aminodextran covalently linked to a triazine derivative. It was
possible to detect less than 0.1 ppb of atrazine, thus below the precautionary limit for
pesticides in drinking water recommended by the European Commission.
A flow analysis system coupled with an immunosensor exploiting the electrogenerated chemiluminescence of luminol was used for the detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in drinking water (Marquette and Blum 1998). The immunosensor is based on a competitive immunoreaction, in which 2,4-D contained in the
water sample and 2,4-D immobilized on the surface of a glassy carbon electrode compete for a luminol-Iabelled anti-2,4-D antibody. After the immunoreaction, the amount
A. Roda . P. Pasini . M. Guardigli
analysis of both freshwater and sea water samples, since the salt content of the sea water
did not interfere in the assay (Roda et al. 1991). Instead, a preliminary desalting procedure was necessary if the sea water sample was preconcentrated before analysis.
A time-resolved fluoroimmunoassay was developed for the detection of benzo(a)pyrene (Ius et al. 1992) on the basis of the previously reported work. This direct heterogeneous immunoassay was developed using a specific antibody labelled with an
isothiocyanatophenyl-EDTA-Eu complex. After the immunoreaction, the lanthanide
complex was dissociated, and the amount of metal ion in solution was determined via
a time-resolved fluorescence measurement upon addition of an enhancement solution forming a luminescent europium complex. The detection limit (about 0.5 ng rnI- 1 )
was low enough for the application of the method on water samples without preliminary extraction or concentration procedures. Phthalate esters, widely used as plastifiers,
were determined in a direct competitive immunoassay based on a time-resolved fluorescence measurement using rabbit antibodies against phthalate esters (Ius et al.1993).
The bound antibodies were detected using a biotinylated anti-rabbit antibody and a
BCPDA-Iabelled streptavidin. Metal luminescence intensity was then measured in the
time-resolved mode upon addition of an excess of europium ion. This assay was able
to detect as low as 0.5 pmol mrl of the most diffused phthalate esters.
A chemiluminescent flow sensor was developed for the determination of organophosphorus (Paraoxon) and carbamate (Aldicarb) pesticides in water (Roda et al.1994).
The flow sensor relies on the inhibition of acetylcholinesterase (either in solution or
immobilized on a solid support) due to pesticides. A series of coupled enzymatic reactions, catalysed by the enzymes choline oxidase and peroxidase immobilized on a
solid support, was used in order to allow the chemiluminescent measurement of the
acetylcholinesterase activity. Detection limits of 0.75 flg rl and 4 flg rl were reported
for Paraoxon and Aldicarb, respectively.
The water sample content of the herbicide chlortoluron was determined using an
enhanced chemiluminescent immunoassay (Kameth et al. 1996) in which the chemiluminescence signal was detected by means of a camera luminometer, providing a
semiquantitative assay based on a photographic record of the luminescent end point.
This assay could represent a rapid, simple and portable means of monitoring multiple
water samples for the presence of chlortoluron or other pesticides. In the reported
example, the assay was able to identify and quantitate the herbicide with good accuracy at or above the European limit for individual pesticides in drinking water.
Detection of atrazine in water was also performed by means of an electrochemiluminescence flow injection immunoassay based on anti-atrazine antibodies labelled
with glucose oxidase (Wilson et al. 1997). This competitive electrochemiluminescent
immunoassay used transparent aminosilanized indium tin oxide-coated glass electrodes, derivatized with aminodextran covalently linked to a triazine derivative. It was
possible to detect less than 0.1 ppb of atrazine, thus below the precautionary limit for
pesticides in drinking water recommended by the European Commission.
A flow analysis system coupled with an immunosensor exploiting the electrogenerated chemiluminescence of luminol was used for the detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in drinking water (Marquette and Blum 1998). The immunosensor is based on a competitive immunoreaction, in which 2,4-D contained in the
water sample and 2,4-D immobilized on the surface of a glassy carbon electrode compete for a luminol-Iabelled anti-2,4-D antibody. After the immunoreaction, the amount