Video approach to chemiluminescence detection using a low-cost complementary metal oxide semiconductor (CMOS)-based camera: determination of paracetamol in pharmaceutical formulations.

A new system for continuous flow chemiluminescence detection, based on the use of a simple and low-priced lens-free digital camera (with complementary metal oxide semiconductor technology) as a detector, is proposed for the quantitative determination of paracetamol in commercial pharmaceutical formulations. Through the camera software, AVI video files of the chemiluminescence emission are captured and then, using friendly ImageJ public domain software (from National Institutes for Health), properly processed in order to extract the analytical information. The calibration graph was found to be linear over the range 0.01-0.10 mg L-1 and over the range 1.0-100.0 mg L-1 of paracetamol, the limit of detection being 10 µg L-1. No significative interferences were found. Paracetamol was determined in three different pharmaceutical formulations: Termalgin®, Efferalgan® and Gelocatil®. The obtained results compared well with those declared on the formulation label and with those obtained through the official analytical method of British Pharmacopoeia. Graphical abstract Abbreviated scheme of the new chemiluminescence detection system proposed in this paper.

Sustained production of superoxide radicals by manganese oxides under ambient dark conditions.

Manganese (Mn) oxides are ubiquitous in the environment and have strong reactivity to induce the transformation of various contaminants. However, whether reactive oxygen species contribute to their surface reactivity remains unclear. Here, sustainable production of superoxide radicals (O2•-) by various MnO2 polymorphs in the dark was quantified and the mechanisms involved were explored. The results confirm that O2•- was produced through one-electron transfer from surface Mn(III) to adsorbed O2. In contrast, no H2O2 was detected due to its decomposition by Mn oxides to form O2•- and Mn(III), leading to the sustained production of O2•- on Mn oxide surfaces. In addition, the production of O2•- was found to make a clear contribution (4 - 28%) to the transformation of a series of halophenols by MnO2, suggesting that the O2•--mediated surface reaction is an important supplement to the direct electron-transfer mechanism in the reactivity of Mn oxides. These findings advance our understanding of the surface reactivity of Mn oxides and also reveal an important but hitherto unrecognized abiotic source of O2•- in the natural environment.

CuO nanosheets-enhanced flow-injection chemiluminescence system for determination of vancomycin in water, pharmaceutical and human serum.

A novel, rapid and sensitive CuO nanosheets (NSs) amplified flow-injection chemiluminescence (CL) system, luminol-H2O2-CuO nanosheets, was developed for determination of the vancomycin hydrochloride for the first time. It was found that vancomycin could efficiently inhibit the CL intensity of luminol-H2O2-CuO nanosheets system in alkaline medium. Under the optimum conditions, the inhibited CL intensity was linearly proportional to the concentration of vancomycin over the ranges of 0.5-18.0 and 18.0-40.0 mg L(-1), with a detection limit (3σ) of 0.1 mg L(-1). The precision was calculated by analyzing samples containing 5.0 mg L(-1) vancomycin (n=11) and the relative standard deviation (RSD) was 2.8%. Also, a high injection throughput of 120 sample h(-1) was obtained. The CuO nanosheets were synthesized by a sonochemical method. Also, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were employed to characterize the CuO nanosheets. The method was successfully employed to determine vancomycin hydrochloride in environmental water samples, pharmaceutical formulation and spiked human serum.