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This study investigated a method for the validation and determination of measurement uncertainty for the simultaneous determination of synthetic phenolic antioxidants (SPAs) such as propyl gallate (PG), octyl gallate (OG), dodecyl gallate (DG), 2,4,5-trihydroxy butyrophenone (THBP), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in edible oils commonly consumed in Korea. The validated method was able to extract SPA residues under the optimized HPLC-UV and LC-MS/MS conditions. Furthermore, the measurement of uncertainty was evaluated based on the precision study. For HPLC-UV analysis, the recoveries of SPAs ranged from 91.4% to 115.9% with relative standard deviations between 0.3% and 11.4%. In addition, the expanded uncertainties of the SPAs ranged from 0.15 to 5.91. These results indicate that the validated method is appropriate for the extraction and determination of SPAs and can be used to verify the safety of edible oil products containing SPAs residues., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Simple dynamic light scattering (DLS)-based methodologies were developed to determine primary particle size distribution of iron oxide particles in simulated gastrointestinal fluid. Iron oxide particles, which easily agglomerate in aqueous media, were converted into dispersed particles by modification of surface charge using citric acid and sodium citrate. After the modification, zeta-potential value decreased to -40mV at pH 7. Mean particle diameters in suspensions of iron oxide nano- and microparticles stabilized by the mixture of citric acid and sodium citrate were dramatically decreased to 166 and 358nm, respectively, which were close to the particle size distributions observed in the micrographs. In simulated gastrointestinal fluid, both iron oxide nano- and microparticles were heavily agglomerated with particle diameters of almost 2600 and 5200nm, respectively, due to charge shielding on the citrate-modified surface by ions in the media. For determining primary particle size distribution by using DLS-based approach, the iron oxide particles incubated in the simulated gastrointestinal fluid were converted to monodisperse particles by altering the pH to 7 and electrolyte elimination. The simple DLS-based methodologies are well suited to determine primary particle size distribution of mineral nanoparticles at various physical, chemical, and biological conditions., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In polymeric nanoparticle preparation, despite similar conditions, large fluctuations in particle size distributions are usually observed. Herein, we demonstrate that the intermittent addition of a desolvating agent can improve reproducibility in the preparation of polymeric bovine serum albumin (BSA) nanoparticles. Using this modification, BSA nanoparticles of controlled size can be manufactured with narrow particle size distributions. In our study, ethanol as a desolvating agent was added intermittently to 1% BSA solutions at different pHs with stirring at 700rpm. The effect of the preparation parameters on size and optical density of the fabricated nanoparticles were studied. The average particles sizes of BSA nanoparticles prepared at pH values of 6, 7 and 9 were approximately 100, 200 and 300nm, respectively. As ethanol addition increased, desolvation of BSA molecules resulted in formation of loose-structured particles with pH-dependent size. Beyond that, only particle density increased, but size remained unchanged with further addition of ethanol. Consistently uniform particle size distribution was achieved by adding ethanol intermittently., (Copyright © 2013 Elsevier Ltd. All rights reserved.)