RESUMEN
Paper-based electrochemical sensors (PESs) have been evidenced as analytical strategies for employing simple, low-cost, portable and disposable sensing platforms that can be used in many application areas. Recently, PESs have gained extensive attention because of their advantages of advanced sensitivity and selectivity during detection provided by electrochemistry, compared with microfluidic paper-based analytical devices (µPADs) that still lack these advantages. Also, it can be expected that PESs can better meet current user demands, making them a stand-out analytical tool because of their capability for multiple analyte detection and their compatibility in a variety of application areas, like clinical diagnosis, environmental monitoring and food quality control. Herein, in this mini review, we present an overview of recent developments in PESs over the last decade, focusing on existing fabrication techniques and application areas, specifically in relation to clinical diagnostics, food quality control and environmental monitoring, where simple and portable analytical devices are greatly needed. A summary and future outlooks for PESs are also discussed.
RESUMEN
The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-West Ethiopia were analyzed using GC-ECD. Results of the analysis indicated that all samples contained detectable quantities of p,p'-DDT and its metabolites, p,p-DDE and p,p-DDD, but none of the other OCPs analyzed. Mean levels of total DDT in the human and cow milk samples in the three areas were 12.68 and 0.389 µg g(-1) respectively. The distributions of p,p-DDT, p,p-DDE and p,p-DDD in the human milk samples from the three locations followed the same trend in which the proportion of p,p-DDT was the highest in all the three cases, comprising 55-71% of total DDT, followed by p,p-DDE, 26-39%, and the least, p,p-DDD of 2-5%. The mean ratio of DDT/DDE concentration for the three areas was calculated to be 2.01. This value was much higher than the values reported from other countries in earlier studies and indicates the existence of a higher quantity of DDT from a fresh input in the three study areas. The mean estimated daily intake of DDT by infants from mother's milk in the three locations was found to be 62.17 µg kg(-1) body weight, which is about three times higher than the acceptable daily intake set by WHO/FAO for total DDT, 20 µg kg(-1) of body weight. This alarmingly high daily intake value is a cause for concern, since children are highly susceptible to effects from such environmental contaminants. The study has revealed that people in the study areas are facing exposure to DDT from recent use. The observed contamination of mother's milk and the possible transfer of the contaminant from mother to child is an obvious risk associated with breast-feeding in the study areas and possibly in other parts of the country too.
