Determination of carbaryl in natural water samples by a surface plasmon resonance flow-through immunosensor.
The analysis of carbaryl in natural water samples was accomplished using a portable immunosensor based on surface plasmon resonance (SPR) technology. The assay was based on a binding inhibition immunoassay format with the analyte derivative covalently immobilized on the sensor surface. An alkanethiol self-assembled monolayer (SAM) was formed onto the gold-coated sensor surface to allow the reusability of the same sensing surface during 220 regeneration cycles. Reproducibility was evaluated by performing three independent assays in triplicate on 3 different days. The batch-assay variability was also calculated using three different gold-coated sensor surfaces. The intra- and inter-day relative standard deviation were 8.6 and 15.3%, respectively, whilst a variation of 7.4% in assay sensitivity was obtained by employing different sensor chips. The lowest detection limit, calculated as the concentration providing a 10% decrease of the blank signal, was of 1.38 microg L(-1). Matrix effects were also evaluated in different water types, showing I50 values (carbaryl concentrations that produced a 50% decrease of the blank signal) within the range of carbaryl standard curves in distilled water (2.78-3.55 microg L(-1)). The carbaryl immunoassay performance was validated with respect to conventional high-performance liquid chromatography-mass spectrometry (HPLC-MS). The correlation between methods was in good agreement (r2 = 0.998, 0.999 and 0.999) for the three types of natural water samples tested. A complete assay cycle, including regeneration, is accomplished in 20 min. All measurements were carried out with the SPR sensor system (beta-SPR) commercialised by the company SENSIA, SL (Spain). The small size and low-time of response of the beta-SPR platform would allow its utilization in real contaminated locations.
Mauriz
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Microelectronics National Centre CNM-CSIC, Isaac Newton, 8 - 28760 Tres Cantos, Madrid, Spain. elba@imm.cnm.csic.es
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Abad
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Montoya
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Hildebrandt
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Barceló
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Lechuga
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D015374:Biosensing Techniques; D012721:Carbaryl / Q000032:analysis*; D005618:Fresh Water / Q000032:analysis* / Q000737:chemistry; D007118:Immunoassay; D007306:Insecticides / Q000032:analysis*; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry; D020349:Surface Plasmon Resonance; D014874:Water Pollutants, Chemical / Q000032:analysis
D007306:Insecticides; D014874:Water Pollutants, Chemical; D012721:Carbaryl