HPLC and GC Methods for Determination of Lubricants and Their Evaluation in Analysis of Real Samples of Polyethylene

Bifunctional Amphiphilic Nanospikes with Antifogging and Antibiofouling Properties

Over the past few decades, extensive research efforts have been devoted to developing surfaces with unique functionalities, such as controlled wettability, antibiofouling, antifogging, and anti-icing behavior, for applications in a wide range of fields, including biomedical devices, optical instruments, microfluidics, and energy conservation and harvesting. However, many of the previously reported approaches have limitations with regard to eco-friendliness, multifunctionality, long-term stability and efficacy, and cost effectiveness. Herein, we propose a scalable bifunctional surface that simultaneously exhibits excellent antifogging and antibiofouling properties based on the synergistic integration of an eco-friendly and bio-friendly polyethylene glycol (PEG) hydrogel, oleamide (OA), and nanoscale architectures in a single flexible platform. We demonstrate that the PEG-OA-nanostructure hybrid exhibits excellent antifogging performance owing to its enhanced water absorption and spreading properties. We further show that the triple hybrid exhibits notable biofilm resistance without the use of toxic biocides or chemicals by integrating the "fouling-resistant" mechanism of the PEG hydrogel, the "fouling-release" mechanism of OA, and the "foulant-killing" mechanism of the nanostructures.

COVID-19 discarded disposable gloves as a source and a vector of pollutants in the environment

The appearance of the virus SARS-CoV-2 at the end of 2019 and its spreading all over the world has caused global panic and increase of personal protection equipment usage to protect people against infection. Increased usage of disposable protective gloves, their discarding to random spots and getting to landfills may result in significant environmental pollution. The knowledge concerning possible influence of gloves and potential of gloves debris on the environment (water, soil, etc.), wildlife and humans is crucial to predict future consequences of disposable gloves usage caused by the pandemic. This review focuses on the possibility of chemical release (heavy metals and organic pollutants) from gloves and gloves materials, their adsorptive properties in terms of contaminants accumulation and effects of gloves degradation under environmental conditions.

Oleamide, a Bioactive Compound, Unwittingly Introduced into the Human Body through Some Plastic Food/Beverages and Medicine Containers

The purpose of the study was to investigate the migration of oleamide, a polymer lubricant, and a bioactive compound, from various plastic, marketed containers for food/beverages and medicines into polymer contact liquid. Methanol, food/medicine simulants or real samples were used to extract polymer leachables and extractables. Migrated oleamide into polymer contact liquids was determined by ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). The concentration of oleamide in the extracts of medicinal and insulin syringes was 7351 ng mL^-1 and 21,984 ng mL^-1, respectively. The leachates of intravenous (i.v.) infusion bottle, medicinal and insulin syringes contained 17 ng mL^-1, 12 ng mL^-1 and 152 ng mL^-1, respectively. Oleamide in the extracts of dummies ranged from 30 to 39 ng mL^-1, while in the leachates of baby bottles, from 12 to 23 ng mL^-1. Leachates of soft drink bottles contained from 6 to 15 ng mL^-1 oleamide, milk bottles from 3 to 9 ng mL^-1, liquid yogurt bottles 17 ng mL^-1 and water bottles from 11 to 18 ng mL^-1. Bottled real matrices of oil and milk contained oleamide in the range from 217 to 293 ng mL^-1. Moreover, the source of migrated oleamide (e.g., containers, caps, other parts) was identified. Oleamide is listed in the current EU regulations without a specific migration limit. Accordingly, these values are considered of no concern, unless future toxicological studies prove the opposite.

Interference of oleamide with analytical and bioassay results

During sample preparation and analysis, samples are coming in contact with different labware materials. By four unrelated analytical (phytochemical and pharmaceutical) case-studies and employing different analytical techniques, we demonstrated the potential misinterpretation of analytical results due to the use of contaminants-leaching labware during sample handling. Oleamide, a common polymer lubricant and a bioactive compound, was identified as a main analytical interference, leaching from different labware items into solvents, recognised as chemically compatible with the tested polymer material. Moreover, anti-inflammatory effect of oleamide at 100 μg mL⁻¹ and considerable pro-inflammatory effect of the plastic syringe extractables (containing oleamide) at the same level were shown in a TLR4-based bioassay. Taking these results into account, together with the fact that oleamide can be a compound of natural origin, we would like to notify the professional public regarding the possible erroneous oleamide-related analytical and bioassay results due to the use of oleamide-leaching labware. Researchers are alerted to double check the real source of oleamide (labware or natural extract), which will prevent further reporting of false results. Analysis of procedural blanks with de-novo developed UHPLC-ESI-MS method is, among some other strategies, proposed for detection of oleamide interference and avoidance of misleading results of certain analyses.

Detection and quantification analysis of chemical migrants in plastic food contact products

Plastic food contact materials (FCM)-based products were widely used in everyday life. These products were normally imposed to strict regulations in order to pass the enforcement tests of compliance as a prefix condition. However, even in these “qualified” materials, unknown chemical substances, not involving in legislation lists, could migrate from FCM. In this perspective, the present work aims to thoroughly analyze by means of Gas Chromatography-Mass Spectrometry (GC-MS) the different substances/migrants in 120 qualified FCM plastic products. Unexpectedly, among the identified compounds (nearly 100), only 13% was included in the permitted list of Commission Regulation EU No 10/2011. All the identified compounds were classified into 11 categories according to their chemical structure and the FCM type, whereas toxicology data were in addition analyzed. Each plastic type exhibited different preferences of chemical migrants. Fortunately, most of the compounds identified were of low toxicity, and only 4 chemicals were included in priority lists and previous literature reports as potential risk factors. Subsequently, the accurate amount of these 4 chemicals was determined. The amount of Bis(2-ethylhexyl) adipate (DEHA) and Bis(2-ethylhexyl) phthalate (DEHP) were lower than the SML in Commission Regulation EU No 10/2011, and that of stearamide was under the recommended use quantity. The 2,4-di-tert-butylphenol (2,4-DTBP) was widely exist in the investigated FCM products. Among them, the highest level is obtained in polypropylene/low density polyethylene (BOPP/LDPE) materials, up to 45.568±31.513 mg/kg. In summary, a panel of unlisted chemical migrants were discovered and identified by GS-MS screening. The results implied that plastic FCMs were not so “inert” as they usually considered, and further safety evaluation should be performed toward the complete identification of new substances in FCM products.

Quantification and enzyme targets of fatty acid amides from duckweed root exudates involved in the stimulation of denitrification

Fatty acid amides from plant root exudates, such as oleamide and erucamide, have the ability to participate in strong plant-microbe interactions, stimulating nitrogen metabolism in rhizospheric bacteria. However, mechanisms of secretion of such fatty acid amides, and the nature of their stimulatory activities on microbial metabolism, have not been examined. In the present study, collection, pre-treatment, and determination methods of oleamide and erucamide in duckweed root exudates are compared. The detection limits of oleamide and erucamide by gas chromatography (GC) (10.3ngmL(-1) and 16.1ngmL(-1), respectively) are shown to be much lower than those by liquid chromatography (LC) (1.7 and 5.0μgmL(-1), respectively). Quantitative GC analysis yielded five times larger amounts of oleamide and erucamide in root exudates of Spirodela polyrrhiza when using a continuous collection method (50.20±4.32 and 76.79±13.92μgkg(-1) FW day(-1)), compared to static collection (10.88±0.66 and 15.27±0.58μgkg(-1) FW day(-1)). Furthermore, fatty acid amide secretion was significantly enhanced under elevated nitrogen conditions (>300mgL(-1)), and was negatively correlated with the relative growth rate of duckweed. Mechanistic assays were conducted to show that erucamide stimulates nitrogen removal by enhancing denitrification, targeting two key denitrifying enzymes, nitrate and nitrite reductases, in bacteria. Our findings significantly contribute to our understanding of the regulation of nitrogen dynamics by plant root exudates in natural ecosystems.

Comparison of three gas chromatography methods for the determination of slip agents in polyethylene films

Polymers require the use of some slip agents, such as oleamide and erucamide, in order to reduce their friction coefficient and to make films easier to handle. In this communication, three analytical methods consisting in pressurized liquid extraction (PLE) and gas chromatography (GC) are used to determine oleamide and erucamide in polyethylene films. The sample was extracted with pure isopropanol (two times) at 105 degrees C for 16 min. Then, the liquid extract containing oleamide and erucamide was analyzed by GC and three different detection systems: flame ionization detector (FID), thermoionic selective detector (TSD) and ion-trap mass spectrometry detector (MSD). Oleamide and erucamide were separated using a 30 m x 0.25 mm (I.D.) 5% phenyl-95% dimethyl-polysiloxane capillary column in 12 min. The chromatographic methods were characterized and compared in terms of repeatability, linearity and sensitivity. The GC-FID and GC-TSD methods were linear up to about 60 microg ml(-1), whereas the linear range for the GC-MSD method was shorter, from 20.5 to 42 microg ml(-1). LODs identified with GC-MSD were two times higher than those identified with the other two methods. Repeatability values (expressed as relative standard deviation) of less than 2.5% were found for FID and TSD but they were above 10% for MSD. Finally, each method was applied to determine the content of erucamide and oleamide in several polyethylene films and the results obtained were compared with those obtained from the nitrogen content measured by pyrolysis and gas-phase chemiluminescence. No significant differences were observed between the results of the methods.