Spectrophotometric determination of Irgafos 168 in polymers after different sample preparation procedures

Valoration of the Synthetic Antioxidant Tris-(Diterbutyl-Phenol)-Phosphite (Irgafos P-168) from Industrial Wastewater and Application in Polypropylene Matrices to Minimize Its Thermal Degradation

Industrial wastewater from petrochemical processes is an essential source of the synthetic phenolic phosphite antioxidant (Irgafos P-168), which negatively affects the environment. For the determination and analysis of Irgafos P-168, DSC, HPLC-MS, and FTIR methodologies were used. Solid phase extraction (SPE) proved to be the best technique for extracting Irgafos from wastewater. HPLC-MS and SPE determined the repeatability, reproducibility, and linearity of the method and the SPE of the standards and samples. The relative standard deviations, errors, and correlation coefficients for the repeatability and reproducibility of the calibration curves were less than 4.4% and 4.2% and greater than 0.99955, respectively. The analysis of variance (ANOVA), using the Fisher method with confidence in 95% of the data, did not reveal significant differences between the mentioned parameters. The removal of the antioxidant from the wastewater by SPE showed recovery percentages higher than 91.03%, and the chemical characterization of this antioxidant by FTIR spectroscopy, DSC, TGA, and MS showed it to be structurally the same as the Irgafos P-168 molecule. The recovered Irgafos was added to the polypropylene matrix, significantly improving its oxidation times. An OIT analysis, performed using DSC, showed that the recovered Irgafos-blended polypropylene (PP) demonstrated oxidative degradation at 8 min. With the addition of the Irgafos, the oxidation time was 13 min. This increases the polypropylene’s useful life and minimizes the environmental impact of the wastewater.

[The specific features of the distribution of 2,4- and 2,6-di--butylhydroxybenzenes on the body of the warm-blooded animals]

The present study was designed to elucidate the character of the distribution of 2,4- and 2,6-di-tret-butylhydroxybenzenes (2,4-DTBHOB and 2,6-DTBHOB respectively) in the body of the warm-blooded animals (rats) following the administration of the three-fold LD₅₀ dose into the stomach. Both 2,4-DTBHOB and 2,6-DTBHOB were extracted from the blood and the organs of the perished animals by means of two-fold incubation of the sampled tissues in ethyl acetate with the subsequent purification of the isolates by passing the extracts through a L 40/100 mcm silicagel column using hexane:dioxane (8.5:1.5) for 2,4-DTBHOB and hexane:dioxane (97.5:2.5) for 2,6-DTBHOB as eluants. The compounds of interest were identified and quantified by means of TLC, HPLC, and UV-spectrometry. The study has shown that both 2,4-DTBHOB and 2,6-DTBHOB were present in the organs and blood of the poisoned animals in the unmetabolized form. Their largest amounts (mg/100 g) were found in the contents of the stomach, the small intestines with the contents and in the spleen.

Evaluation of solvent systems for optimized extractables studies of single use bioprocessing solutions

Despite their advantages, there is concern that single-use systems used in biopharmaceutical manufacture might release potentially toxic substances during standard unit operations that negatively impact cell growth. Characterization of the extractables profile for single-use systems is necessary to know which compounds potentially become leachables under operational cell culture conditions. A key issue in the design of extractables studies is the composition of the model solvent, in particular its pH and polarity. In this study, a new approach, based on design of experiments (DoE), has been applied to determine the composition of the model solvent for extractable profiling of single-use bags (SUBs). Particular focus was placed on the determination of the degradation products of the antioxidant Irgafos 168^®, due to evidence that some of these degradation products have cytotoxic effects on CHO cells. Results indicated that 2-propanol:water is the most appropriate solvent for the extraction of highly hydrophobic compounds with polar groups and/or acid-base properties from SUBs. The described DoE approach simplifies the number of experiments, evaluates all possible solvent water mixtures to select the best extraction solvent based on polarity, establishes the influence of each variable and provides information about variable interaction, which represents an important improvement over current best practice. The developed approach was applied to seven SUBs from different vendors and production dates facilitating the identification of potentially non-satisfactory films for cultivation of CHO cell lines under process conditions.

Human exposure assessment to a large set of polymer additives through the analysis of urine by solid phase extraction followed by ultra high performance liquid chromatography coupled to tandem mass spectrometry

Polymer items are extensively present in the human environment. Humans may be consequently exposed to some compounds, such as additives, incorporated in these items. The objective of this work is to assess the human exposure to the main additives such as those authorized in the packaging for pharmaceutical products. The urinary matrix was selected to optimally answer this challenge because it has already been proven that the exposure to chemicals can be revealed by the analysis of this biological matrix. A multi-residue analytical method for the trace analysis at ng/mL in human urine was developed, and consisted of an extraction of analytes from urine by solid phase extraction (SPE) and an analysis by ultra-high performance liquid chromatography coupled to a tandem mass spectrometer (UHPLC-MS/MS). Even if the quantification of these compounds was an analytical challenge because of (i) the presence of these substances in the analytical process, (ii) the diversity of their physicochemical properties, and (iii) the complexity of the matrix, the optimized method exhibited quantification limits lower than 25ng/mL and recoveries between 51% and 120% for all compounds. The method was validated and applied to 52 human urines. To the best of our knowledge, this work presents the first study allowing the assessment of the occurrence of more than twenty polymer additives at ng/mL in human urine.