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The effects of six synthetic imidazolium-based ionic liquids (ILs) on the Cu(II)-catalyzed chemiluminescence of lucigenin (Luc-CL) in the pH range 6.0-11 were investigated. Preliminary experiments found that the CL emission was strongly enhanced or inhibited in the presence of the ILs. The degree of enhancement or inhibition of the CL intensity in the presence of each IL was related to the molecular structure of the IL, the medium used, and the pH. The maximum enhancement of the CL intensity was observed at pH 9.0 (amplification factor = 443). This decrease in the pH at which maximum CL enhancement occurred and the substantial signal amplification of the Luc-CL may be related to a strong interaction between Cu(II) and the imidazolium ring of superior ILs at this pH. Additionally, the formation of IL microdomains in semi-aqueous media permitted more solubility of the product yielded by the Luc-CL reaction (N-methylacridone), which could increase the CL intensity. To obtain consistent data on the catalytic efficiency of Cu(II) in the presence of various ILs as well as the corresponding CL emission intensities, fluorescence quantum yields (Φ F) of lucigenin were measured under the same conditions. Comparison of the data pointed to the mechanism that controls the properties of Luc-CL in the presence of the Cu(II)/IL complexes. Based on the catalytic effect of the Cu(II)/IL complex and the measurement of the enzymatically generated H2O2, a novel, simple, and sensitive CL method for determining glucose with a detection limit (LoD) of 6.5 μM was developed. Moreover, this method was satisfactorily applied to the determination of glucose in human serum and urine samples. Graphical Abstract The lucigenin chemiluminescence assay for H2O2 and glucose using imidazolium-based ionic liquid derivatives/Cu(II) complexes as efficient catalysts at pH 9.0.

A new sensitive chemiluminescence (CL) procedure for the detection of hexythiazox (HXTZ) is presented, based on the quenching effect of the HXTZ in the luminol-H2O2 system using gold nanoparticles (GNPs) as a catalyst. The Box-Behnken design matrix and response surface methodology (RSM) have been applied in designing the experiments for studying the interactive effects of the three most important variables pH, luminol, and H2O2 concentrations on the CL intensity of luminol catalysed by GNPs. Under the optimal conditions, the CL intensity was linear with HXTZ concentration in the range of 0.017-0.42 μg mL(-1), and the limit of detection (LoD) was 0.011 μg mL(-1). The procedure has been successfully applied to the detection of HXTZ residues in citrus fruits and water samples at trace levels. Mean recoveries obtained were between 84.0% and 95.3%, with a repeatability precision of <6%. Meanwhile, the possible mechanism of the inhibited CL intensity was discussed., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

A novel, simple, cheap, and high sensitivity batch chemiluminescent method for the determination of catecholamine drugs, epinephrine (E), dopamine (DA) and methyldopa (MD) at microgram levels in pharmaceutical formulations is described. The method is based on a chemiluminescence (CL) system arising from the reaction of bis(2,4,6-trichlorophenyl) oxalate (TCPO) with H₂O₂ in the presence of a novel fluorescer, furandicarboxylate, and is proposed as a new analytical method for the determination of catecholamines. The method is based on the inhibition of CL emission by DA and its enhancement by E and MD. Under optimal conditions, good linear ranges were obtained, 0.5 - 12.7, 0.06 - 1.83 and 0.069 - 3.52 μg/mL with detection limits of 0.30, 0.03 and 0.04 μg/mL (S/N = 3) for DA, E and MD, respectively. Moreover, a pooled-intermediate model was used to determine the kinetic parameters of CL with and without catecholamines and a possible CL mechanism was discussed.

Furan derivatives (synthesized and purified in organic laboratories) are a great interest as fluorescent emitters for peroxyoxalate chemiluminescence. Reaction of peroxyoxalates such as bis-(2,4,6-trichloro-phenyl) oxalate with H(2)O(2) can transfer energy to fluorophore via formation of dioxetanedione intermediate. Furan derivatives used as a novel fluorescer in this study which produces a blue light in the chemiluminescence systems. The relationship between the chemiluminescence intensity and concentrations of TCPO, sodium salicylate, hydrogen peroxide and the fluorescer has been investigated. The linear ranges for Furan derivatives were 0.25-5 × 10(-4) M and 0.1-5 × 10(-4) M (A and B compounds, respectively). Kinetic parameters for the peroxyoxalate-chemiluminescence were also calculated from the computer fitting of the corresponding chemiluminescence intensity/time profiles.

The chemiluminescence characteristics of seven different cumarin derivatives were studied in detail. The fluorescence and chemiluminescence spectra were compared; all cumarins used were found to act as blue fluorescers. The intensity and kinetic parameters for the chemiluminescent systems were evaluated from computer fitting of the resulting intensity-time plots. Among different cumarin derivatives used, 7-amino-4-trifluoromethylcumarin revealed the most promising characteristics as an efficient blue fluorescent emitter.