This study describes the use of uncured polydimethylsiloxane (PDMS) as a binder agent to prepare carbon paste electrodes (CPEs). A comparative study between the properties of CPEs prepared with PDMS and mineral oil Nujol®, the most common binder agent for CPEs, was carried out. Cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry showed that PDMS-CPEs presented higher electrical conductivity, active electrochemical area, and wider useful potential window compared with Nujol®-CPEs. Moreover, PDMS-CPEs were more stable in aqueous mixtures containing 50% (v/v) of ethanol or methanol than Nujol®-CPEs. PDMS-CPEs have also provided higher sensitivity and lower limit of detection to propranolol than Nujol®-CPE. Therefore, this study demonstrated that PDMS is a promising alternative binder agent able to produce CPEs with superior chemical/electrochemical stability and improved analytical performance.

Cellulose derivatives still receive special attention in today biomedical applications due to their biocompatibility, ability to form resistant membranes and compatibility with various bioactive agents. In this work, cellulose acetate (CA) was used to prepare membranes with different morphologies aiming to evaluate the release profile of the drug ibuprofen (IBF). The IBF incorporation was performed by the addition of 10% of the drug in an 8% (w/w) CA/acetone solution. The morphology of the membranes was modified by the addition of water, used as porogenic agent. Drug release assays showed the effect of morphology on the cumulative drug release curves. The symmetric membrane exhibited retention of significant amounts of the drug and a slow release process that lasted for more than 50 hours. The asymmetric porous membranes presented different behavior with greater amount of drug released in less time of release. The kinetic parameters calculated from the Higuchi and Korsmeyer/Peppas models indicated release profiles controlled by diffusion/solution process in the polymer matrix. The results revealed that the interactions established between IBF, CA and the matrix morphology are significant factors for the kinetic control of the drug release process and enable to choose different applications of the membranes loaded with IBF.

This work presents a voltammetric method for Zn2+ determination in antiseptic dusting powder and multivitamin commercial samples, combining an alkaline extraction using NaOH aqueous solution with a carbon paste electrode chemically modified with Bi anchored on Amberlite® IR120 ion exchange resin (CPEAmb/Bi). The best conditions for electrode preparation were: 10% (m/m) of Amberlite® IR 120; 30 s Bi3+ accumulation time (open circuit) in 0.5 mmol L-1 Bi3+ solution prepared in 0.1 mol L-1 acetate buffer (pH = 5.5). The analytical curve for Zn2+ using the CPEAmb/Bi presented linear range from 0.05 to 8.2 µmol L-1 and the limit of detection was 10 nmol L-1. The voltammetric method was simple, fast, efficient and low-cost for the Zn2+ determination in antiseptic dusting powder and multivitamin samples.