Abstract Microplastic pollution has become a global environmental problem and is a cause of great concern. To evaluate the biological effects of microplastics, microplastics in organisms need to be accurately quantified. The quantification of microplastics in organisms using the fluorescence intensity is common; the digestion of biological samples is an important pretreatment method. However, the microplastics may be destroyed by digestion, which affects the fluorescence intensity of the microplastics and results in large deviations between measured and true values. In this study, six commonly used digestive agents were studied: KOH, N a OH , H 2 O 2 , HNO 3 , HNO 3 : hcl, and HNO 3 : HClO 4 . The effect of different digestion methods on the fluorescence intensity and surface morphology of microplastics was studied and the most suitable protocol was selected. The results show that, among the six different digestion methods, KOH digestion(100 g·L -1 , 60℃)has the least influence on the fluorescence intensity of the microplastics and does not affect their surface morphology. The other five digestion methods lead to different degrees of reduction of the fluorescence intensity of microplastics and damage the microplastics' surface(aggregation, bubbles, scratches, and depressions). In addition, the KOH digestion method was used to extract microplastics from biological samples. The recovery rate was≥96.3%±0.5%, indicating that the KOH digestion method is suitable for fluorescent microplastics in biological samples.

Abstract   Effective control of food quality and safety requires analytical methods that guarantee the reliable determination of any substance potentially harmful to the consumer that may be present in the food prior to its distribution and marketing. One of the analytical approaches that contributes to guarantee this objective encompasses a series of techniques that have in common the use of antibodies as essential elements for the detection of the target analyte, and which together are called immunochemical methods. This article aims to provide a basic overview of the biochemical principles underlying these technologies and their advantages and limitations in the determination of chemical contaminants, residues and additives in food matrices. The last part discusses some of our initiatives in this field that have resulted in commercially available rapid kits after transferring the corresponding technology to the industrial sector.

Abstract The present study has as objective the analysis and characterization of a sample of an Ecuadorian feldspar, by means of XRD, SEM and TGA techniques, for the microstructural analysis of mineral phase and chemical composition. Qualitative and quantitative X-ray diffraction analysis by Rietveld refinement revealed that this feldspar is composed of 33.31% Albite, 15.70% Quartz and a large percentage by weight of 50.99% amorphous material. To validate these results, the uncertainty of the measurement was investigated and calculated by statistical analysis of standard deviation, giving as results an uncertainty error of ±0.87wt%, ±0.23wt% and ±0.89wt% respectively for the percentages by weight of the minerals found in this analysis. The result by SEM shows the presence of Albite in the feldspar exhibiting laminar twinning and characterized by randomly dispersed spherical quartz and plagioclase inclusions.