Detail Multiway calibration of excitation-emission matrix fluorescence spectra with environmental applications Bibliografi Author: JiJi, Renee Denise ; Gust, Devens (Advisor) Topik: CHEMISTRY; ANALYTICAL Bahasa: (EN )    ISBN: 0-599-67405-9     Penerbit: Arizona State University     Tahun Terbit: 2000     Jenis: Theses - Dissertation Fulltext: 9963148.pdf (0.0B; 0 download) Abstract A compact, field portable excitation-emission matrix (EEM) fluorometer was constructed. The EEM fluorometer has demonstrated 16 hours of continuous use from two 12 volt (V) deep cycle batteries. The performance of the EEM fluorometer under field and laboratory conditions was investigated using the four naturally fluorescent analytes 1-naphthol, carbaryl, carbofuran and rubrene in aqueous solutions. Detection limits of 0.29 parts per billion (ppb) for 1-naphthol, 1.1 ppb for carbaryl, 223 ppb for carbofuran and 0.90 ppb rubrene, were achieved under field conditions. EEM fluorescence combined with parallel factor analysis (PARAFAC) was employed to resolve the overlapping spectra of 1-naphthol, carbaryl and carbofuran in methanol. The Raman scattering present of in the EEM spectra directly overlapped the fluorescence signal of carbofuran. Traditional PARAFAC inefficiently models the Raman scattering, resulting in prediction and calibration errors when a significant background is present. A weighted-PARAFAC (W-PARAFAC) model is applied to EEM fluorescence spectra of carbamate pesticides to aid with calibration in the presence of Raman scattering. W-PARAFAC is also applied to the determination of three polynuclear aromatic hydrocarbons (PAHs). The weighted algorithm is required to incorporate saturated channels of the charge-coupled device (CCD) detector into the calibration model. Decreases in both calibration errors and limits of detection were observed when W-PARAFAC was employed versus traditional PARAFAC. In addition to naturally fluorescent pesticides, non-fluorescent dichlorodiphenyltrichloroethane (DDT)-type pesticides were studied based on interactions between the pesticides and the solvatochromic dye, Nile Red. Interaction was observed for six DDT-type pesticides, including DDT. Nile Red is weakly fluorescent in aqueous solution with an emission maximum around 660 nm. In the presence of DDT-type pesticides the emission maximum of Nile Red is blue shifted, resulting in two distinct EEM spectra. The intensity of the second fluorescence signal is directly proportional to the amount of pesticide in solution. Mid ppb detection limits were observed for non-fluorescent DDT-type pesticides. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Lihat Sejarah Pengadaan  Konversi Metadata   Kembali

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