Detection, quantification, and characterization of polystyrene microplastics and adsorbed bisphenol A contaminant using electroanalytical techniques

The potential applications of electroanalytical techniques for the quantification and size characterization of nonelectroactive polystyrene microplastics is reported, in addition to characterizing the kinetics of adsorption of bisphenol A on these polystyrene microparticles. The individual adsorption events of very diluted polystyrene microparticles dispersions on glassy-carbon microelectrodes produce the blocking of the charge transfer of a mediator (ferrocene-methanol) thus decreasing the current of the recorded chronoamperogram in a stepwise manner. The magnitude of the current steps are in the order of pA values and can be related to the diameter of the plastic microparticles in the size range 0.1 to 10 µm. The frequency of the current steps in the domain time used (120 s) allows to quantify the number concentration of these microparticles in the range 0.005 to 0.500 pM. Electrochemical impedance spectroscopy confirms the adsorption of the polystyrene microplastics on carbon microelectrodes (and to a lesser extent on platinum microelectrodes) under the same experimental conditions as above. On the other hand, the adsorbed microplastics become concentrators of other pollutants found in the environment. The sensitive differential-pulse voltammetry determination of bisphenol A (linear range 0.80–15.00 µM; detection limit 0.24 µM) was used together with a simple separation procedure for studying the adsorption of bisphenol A on polystyrene microparticles. The adsorption capacity (mg of bisphenol A retained per g of the polystyrene microplastics) decreased from approximately 5.7 to 0.8 mg g−1 with increasing dosages of polystyrene microparticles from 0.2 to 1.6 g l−1. The adsorption isotherms were modeled resulting in a monolayer of bisphenol A adsorbed on the microplastics (i.e., best fitted to a Langmuir model)

The use of antidotes for calcium gluconate extravasation: an experimental study in mice

[Abstract] Background: Calcium gluconate extravasation is a process that can cause serious lesions, such as necrosis and calcification of the soft tissues. The aim of the present study was to analyze the beneficial effects of four possible local antidotes for calcium gluconate extravasation: hyaluronidase, sodium thiosulfate, triamcinolone acetonide, and physiologic saline solution. Methods: Seventy-four BALB/c mice were used in the study. The substances selected for use in this study were calcium gluconate (4.6 mEq/ml), hyaluronidase (1500 IU/ml), sodium thiosulfate (25%), triamcinolone acetonide (40 mg/ml 0.5 mg/kg), and saline solution 0.9%. Five minutes were allowed to lapse after the calcium gluconate infiltration, and then an antidote was infiltrated. After 3 weeks, a skin biopsy was performed and a radiographic and histologic study was carried out. Results: Only in the group infiltrated with sodium thiosulfate did all skin lesions disappear after the 3-week period after infiltration. In the radiographic study, calcium deposits larger than 0.5 mm were observed in 40 percent of cases without an antidote, in 33 percent with triamcinolone acetonide, in 13 percent with a saline solution, and in none with thiosulfate and hyaluronidase. In the histologic study, calcium deposits were found in 53 percent of cases without antidote, 100 percent of cases with triamcinolone acetonide, 33 percent of cases with saline solution, and 13 percent of cases with sodium thiosulfate or hyaluronidase. Conclusion: Sodium thiosulfate and hyaluronidase prevent the development of calcium deposits after calcium gluconate extravasation