RESUMEN
The use of near-infrared spectroscopy (NIRS) based on a low-cost portable instrument for monitoring the quality of the three major formulations of ethanol-based hand sanitizers used for prevention against CoVID-19 disease is described. The quality of the sanitizers was evaluated using two approaches. In the first, a qualitative method was developed to identify gross non-conformities, using NIR spectral data compression by principal components analysis and projection of the spectrum of the tested sample in the principal component space delimited by samples of sanitizers prepared in the laboratory. In the second, a quantitative method was designed to determine the active substance (ethanol) employing multivariate regression based on partial least squares. The results demonstrate that the first approach can be used to detect non-conformities in the sanitizer composition, mostly associated with incorrect ethanol content. The second explores the use of NIRS for determination of the ethanol content in the three formulations aiming the quality control of the sanitizer manufacturing process. The ethanol content can be determined with an absolute root mean square error of prediction (RMSEP) equal to 0.68% (m/m), 0.83% (m/m) and 1.0% (v/v) for the three formulations evaluated. The RMSEP was estimated as 1.3% (m/m) for the commercial products. The measurement protocol takes approximately 1 min and requires only about 120 µL of a sample. Besides, NIRS was employed to compare the rate of volatilization of the ethanol in the different formulations, an important parameter concerning the efficacy of ethanol-based sanitizers.
RESUMEN
The advent of miniaturized NIR instruments, also known as compact, portable, or handheld, is revolutionizing how technology can be employed in forensics. In-field analysis becomes feasible and affordable with these new instruments, and a series of methods has been developed to provide the police and official agents with objective, easy-to-use, tailored, and accurate qualitative and quantitative forensic results. This work discusses the main aspects and presents a comprehensive and critical review of compact NIR spectrophotometers associated with analytical protocols to produce information on forensic matters.
RESUMEN
Nickel-metal hydride batteries (NiMH) are a secondary source of high aggregate value elements, such as nickel, manganese, cobalt, and rare earths, for which recycling typically involves acid lixiviation. Designing the recycling process requires accurate determination of the elements in the leachates, which is hindered by the high complexity of the matrix. In the present study, microwave-induced plasma atomic emission spectrometry (MIP-OES) was selected as the quantitative method for elemental analysis because of its environment friendliness and cost-effectiveness. Multi-energy calibration (MEC) was also pioneeringly evaluated to circumvent matrix effects and simplify the determination of Ce, La, Ni, Co, and Mn in sulfuric acid leachates of NiMH batteries by MIP-OES. The method's analytical performance and accuracy were critically compared with external standard calibration and the standard additions method. MEC yielded superior results, with analyte recoveries within 90-110%, precision (coefficients of variation) from 1.8% to 5.8%, and limits of detection of 10, 20, 1, 400, and 60 µg kg-1 for Ni, La, Mn, Ce, and Co, respectively. The results demonstrated the ability of MEC-MIP-OES to minimize matrix effects, as well as simplify and speed up the analysis of NiMH battery leachates, which is compatible with this high-demand analytical application.