| 1. |
- Badea, M, et al.
(författare)
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A flow immunoassay for alkylphenol ethoxylate surfactants and their metabolites - questions associated with cross-reactivity, matrix effects, and validation by chromatographic techniques
- 2003
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Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 1364-5528. ; 128:7, s. 849-856
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Tidskriftsartikel (refereegranskat)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.
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| 2. |
- Dam, J. S, et al.
(författare)
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Fiber optic system for in vivo real-time determination of tissue optical properties from steady-state diffuse reflectance measurements
- 2000
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Ingår i: PHOTON MIGRATION, DIFFUSE SPECTROSCOPY AND OPTICAL COHERENCE TOMOGRAPHY: IMAGING AND FUNCTIONAL ASSESSMENT. - : SPIE. - 0277-786X .- 1996-756X. - 0819438162 ; 1:31, s. 103-109
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Konferensbidrag (refereegranskat)abstract
- We present a versatile and compact fiber optic probe for real-time determination of the absorption and the reduced scattering coefficients from spatially resolved continuous wave diffuse reflectance measurements. The probe collects the diffuse reflectance at six distances in the range 0.6 - 7.8 mm at four arbitrary wavelengths, which were 660, 785, 805, and 974 nm in these experiments. The maximum sampling rate for one cycle of measurements including all four wavelengths is about 100 Hz. The absorption and the reduced scattering coefficients are extracted real-time from the probe measurements using multivariate calibration methods based on multiple polynomial regression and Newton-Raphson algorithms. The system was calibrated on a 6x7 matrix of Intralipid/ink phantoms with optical properties within typical biological ranges, e.g. at 785 nm, the ranges of the absorption and the reduced scattering coefficients, were 0 - 0.3 /cm and 6 - 16 /cm, respectively. Cross-validation tests shoved that the mean prediction error, relative to the ranges of absorption and the reduced scattering coefficients were 2.8 \% and 1.3 \%, respectively.
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