Chemiluminescent Determination of Cholesterol by Flow Injection Analysis with Immobilized Cholesterol Oxidase

Analytical applications of flow injection with chemiluminescence detection--a review

This paper reviews the literature on analytical applications of flow injection (FI) techniques with chemiluminescence (CL) detection from 1995-1999. The focus is on the application of FI-CL to the quantitative determination of specific analytes in real sample matrices. Therefore, entries have been tabulated under the most appropriate application area, ie pharmaceutical, environmental, foods and beverages and biomedical, as defined by the matrix that has been analysed. Each table lists analytes alphabetically and gives details of the exact sample matrix, the limit of detection (as reported in the original paper) and comments on the CL reaction used.

Evaluation of scavenging activity assessed by Co(II)/EDTA-induced luminol chemiluminescence and DPPH* (2,2-diphenyl-1-picrylhydrazyl) free radical assay

The scavenging activities of three standard antioxidants, quercetin, ascorbic acid, and trolox, were evaluated by Co(II)/ethylenediamine-tetraacetic acid (EDTA)-induced luminol chemiluminescence and the 2,2-diphenyl-1-picrylhydrazyl (DPPH*) free radical assay. Therefore, the aim of this study was to characterise an enzyme-free and time-independent chemiluminescence method for the assessment of the scavenging profile of compounds in a cell-free system using the Co(II)/EDTA-luminol-peroxide system. These results showed that the three standards were efficient and effective in inhibiting both Co(II)/EDTA-induced luminol chemiluminescence and the free radical DPPH*. For all the data obtained in this work, the scavenging activity for the standards tested decreased in the following order: quercetin > trolox > ascorbic acid. The present study has applied a simple and precise procedure for the study of hydroxyl radical scavenging activity by Co(II)/EDTA-induced luminol chemiluminescence, and this was assessed by DPPH* free radical scavenging.

A transition metal enhanced luminol chemiluminescence in the presence of a chelator

We have investigated the chemiluminescence signal of luminol and hydrogen peroxide in the presence of a transition metal (Co(II), Cu(I), Fe(II), Fe(III)) and of a chelator (EDTA, citric acid) in pH 8.5, 9 and 10 borate buffer solutions. We observed that the chemiluminescence intensities of these systems reached a plateau, where they remained stable for a period of 2-30 s. We also observed linearity between the intensity of chemiluminescence and the hydrogen peroxide concentration. The combination of Co(II) and EDTA at pH 9 was found to give the optimum signal with reference to time stability, intensity and reproducibility. Thus, compared to previous chemiluminescence applications, the present results permit us to propose a simple, enzyme-free and time-independent technique for the detection and quantification of hydrogen peroxide.