A new, sensitive and simple spectrofluorometric method for the determination of thiabendazole (TBZ) residues was studied. TBZ on Sephadex G-15 gel, pH 4.70 acetate buffer, is fixed to give fluorescence. The fluorescence of the gel-TBZ system, packed in a 1-mm quartz cell was measured directly using a solid-surface attachment. The applicable concentration range was 1.5-10.0 ng.mL-1 with a relative standard deviation of 1.4% and a detection limit of 0.1 ng.mL-1. The method was applied to the determination of thiabendazole in natural, waste, sea, and residual waters (98-100% recovery). The method is more sensitive and selective than other methods described in the literature. The presence of other fluorescent pesticides (dichlone, carbaryl, morestan, o-phenylphenol) with similar spectral features (lambda exc and lambda em neighboring to excitation and emission wavelengths of the TBZ) did not cause interference.
The polycyclic aromatic hydrocarbons (PAHs) benzo[a]pyrene (BaP) , benzo[a]anthracene (BaA) and pyrene (Pyr), which exhibit native fluorescence in solution, were determined in water at trace levels by solid-phase spectrofluorimetry. The relative fluorescence intensity of BaP, BaA and Pyr fixed on Sephadex 6-25 gel was measured after packing the gel beads in a 1 mm silica cell. By using the synchronous spectra at different values of AA, BaA, BaPand Pyr can be simultaneously determined in the presence of other PAHs. Spectral characteristics of the PAH-gel system are described. The concentration ranges over which the method was applicable were 0.3-2.5 ng ml-1 of BaP, 0.4-3.5 ng ml-1 of BaA and 0.54.5 ng ml-1 of Pyr with relative standard deviations of 1.4,1.3 and 1.5% for BaP, BaA and Pyr, respectively. The detection limits were 0.03 ng ml-1 of BaP, 0.05 ng ml-1 of BaA and 0.08 ng ml-1 of Pyr. The method was applied to the analysis of wafers from different sources.
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