1. |
- Nistor, Catalin, et al.
(author)
-
In-field monitoring of cleaning efficiency in waste water treatment plants using two phenol-sensitive biosensors
- 2002
-
In: Analytica Chimica Acta. - 1873-4324. ; 456:1, s. 3-17
-
Journal article (peer-reviewed)abstract
- Two amperometric biosensors based on the enzymes cellobiose dehydrogenase (CDH) and quinoprotein-dependent glucose dehydrogenase (GDH), have been applied for monitoring the phenolic content in water samples, collected at different stages of a waste water treatment process, thus representing different cleaning levels of two waste water treatment plants (WWTPs). The biosensor measurements were performed in-field, compared with the results obtained by liquid chromatography-mass spectrometry and were further correlated with the cleaning efficiencies of the WWTPs. The effect of several potentially interfering compounds on the sensor response was also studied. The general purpose of the study was to evaluate the potential use of biosensors, not as quantitative tools for phenol analysis, but rather as screening tools indicating a certain trend, i.e. compounds present or not present, and potential correlation with sample toxicity. It was found that the biosensors and LC-MS results were not quantitatively comparable, however, both sensors could follow the decrease of the phenol content from the influent, primary treated and effluent waters. In addition, the correlation between biosensor inhibition and sample toxicity is discussed.
|
|
2. |
- Badea, M, et al.
(author)
-
A flow immunoassay for alkylphenol ethoxylate surfactants and their metabolites - questions associated with cross-reactivity, matrix effects, and validation by chromatographic techniques
- 2003
-
In: Analyst. - : Royal Society of Chemistry (RSC). - 1364-5528. ; 128:7, s. 849-856
-
Journal article (peer-reviewed)abstract
- This paper describes the application and evaluation of a competitive enzyme flow injection immunoassay (EFIIA) for screening of alkylphenol ethoxylate (APEO) surfactants in different water samples based on a generic immunoassay system previously developed ( see E. Burestedt, C Nistor, U. Schagerlof and J. Emneus, Anal. Chem., 2000, 72, 4171 - 4177). The detection limits for octylphenol ethoxylates (OPEOs), nonylphenol ethoxylates (NPEOs), and nonylphenol (NP) were 0.5 mug l(-1), between 2 and 3 mug l(-1), and 50 mug l(-1), respectively, with a sample throughput of 6 h(-1) (i.e., for triplicate analysis of each sample). Different OPEOs and NPEOs were highly cross-reactive within the assay, with sensitivities in the same order of magnitude for all the ethoxylates tested, thus the result obtained by the EFIIA method could be used as an "alkylphenol ethoxylate index". No or minor matrix effects with recoveries between 70 - 120% for the reference analyte NPEO10 in tap, and surface water, and acceptable for rainwater, were observed. Influent and effluent surfactant containing wastewater samples were analysed by EFIIA, LC-MS, LC-Fluoresence (LC-FL), and a commercial microplate ELISA. High recoveries for different concentrations of APEO(10) spiked into a 200 times diluted raw influent and effluent wastewater were achieved with the EFIIA method, however, the found APEO content of the same diluted wastewater samples, before spiking, could not be correlated directly to the chromatographic result by any of the immunoassays, and the possible reasons for this are discussed. The same trend of decreasing APEO content from influent to effluent wastewater could, however, be followed for all methods employed.
|
|
3. |
- Nistor, Catalin, et al.
(author)
-
Detection of Escherichia coli in water by culture-based amperometric and luminometric methods.
- 2002
-
In: Water Science and Technology. - 0273-1223. ; 45:4-5, s. 191-199
-
Journal article (peer-reviewed)abstract
- The application of amperometric biosensor- and chemiluminiscence based methods for rapid detection of viable E. coli in water has been investigated. An amplification of the amperometric signal by a factor of 4 was obtained when the cellobiose dehydrogenase (CDH) biosensor was used instead of a plain graphite electrode for detection of b-galactosidase (b-GAL) activity at 22.5 degrees C. A linear correlation was demonstrated for detection time (DT) vs. initial concentrations (logarithmic units) of E. coli IT1 and E. coli in environmental samples, respectively, by use of the CDH biosensor or a chemiluminometric technique. The study has shown that an E. coli concentration > or = 10(4) cfu/100 mL in environmental samples was determined by the CDH biosensor within one working day. However, further reduction of the DT can be obtained, e.g. by increasing the signal amplification factor using other biosensors.
|
|
4. |
- Rose, A, et al.
(author)
-
GDH biosensor based off-line capillary immunoassay for alkylphenols and their ethoxylates
- 2002
-
In: Biosensors & Bioelectronics. - 1873-4235. ; 17:11-12, s. 1033-1043
-
Journal article (peer-reviewed)abstract
- The application of a quinoprotein glucose dehydrogenase modified thick-film sensor as label detector in a capillary immunoassay (CIA) for xenoestrogens is presented. The detection of the alkylphenols and their ethoxylates is based on the competition between the analyte and tracer molecules for the binding sites of anti-alkylphenol ethoxylate antibodies. This assay is performed off-line in small disposable PVC capillaries coated with immobilized antibodies. This format allows the combination of the assay with a small portable device potentially useful for on-site environmental monitoring. Beside high amplification the utilization of beta-galactosidase as enzyme label allows the direct combination with a GDH biosensor at optimal pH conditions. The bioelectrocatalytic properties of this biosensor offer an additional amplification and thus allow a very sensitive quantification of 4-aminophenol, generated by the beta-galactosidase. Detection limits of the analytes in the mug/l range were obtained, while other phenolics and surfactants showed no or very little cross reactivity.
|
|