Milli-Q Water Research Articles

Characterization of polyethylene and polyurethane microplastics and their adsorption behavior on Cu2+ and Fe3+ in environmental matrices

As the world faces growing environmental challenges, understanding the nature of microplastics—such as Low-Density Polyethylene (LDPE) and Polyurethane (PU)—and their transformation in water-based environments is necessary for predicting and mitigating their effects. In this study, we investigated their physicochemical characteristics, presence of impurities, colloidal behavior, and sorption capacity to understand better how microplastics behave and transform in the environment, including their role in transporting heavy metals. The two types of microparticles investigated fall into distinct size ranges, approximately 70 microns for PE particles and around 5 microns for PU particles. Both samples showed a spherical morphology and an evident surface micro-roughness. The elemental and thermal analysis did not show the presence of any significant metal impurities. The zeta-potential measurements as a function of pH provided insights into the dispersion behavior of microplastics (MPs) in freshwaters, suitable for the growth of Zebrafish (Egg water) and Daphnia magna (Elendt M7 Water). Both materials showed in bidistilled water negative zeta potential (ZP) at natural pH (ZP = − 51.0 ± 4.3 mV at pH = 6.6 and ZP = − 29.5 ± 1.4 mV at pH = 5.6 for LDPE and PU, respectively), justified by the presence of surface-active charged impurities. In saline media, ZP vs. pH curves were flatter, with ZP values near 0 mV, confirming the reduced colloidal stability from higher ionic strength and double-layer compression. Finally, we assessed the metal adsorption capacity to establish the role of microplastics in the transport of heavy metals in the environment. We observed selective adsorption for Cu2⁺ ions, which was both medium-dependent (more ions adsorbed in Elendt M7) and plastic-dependent, with PU showing a stronger affinity for Cu2⁺ in MilliQ and Egg water. On the contrary, both plastics showed similar adsorption capacity for Fe3⁺ ions across all media.

First evidence that antibiotic-resistant bacteria are inactivated by chemical species produced through the solar photosensitization of ciprofloxacin in water.

For the first time, using a chemical pollutant (an antibiotic) as a photosensitizer to improve the elimination of a microbiological contaminant of emerging concern (antibiotic-resistant bacteria) is presented. The effect of ciprofloxacin (CIP) on the inactivation of three light-promoted antibiotic-resistant bacteria (ARB) was evaluated. Ciprofloxacin-resistant Escherichia coli, ciprofloxacin-resistant Staphylococcus aureus, and carbapenem-resistant Klebsiella pneumoniae. Firstly, the photosensitizing effect of CIP on E. coli inactivation was studied. Irradiated CIP (1ppm) induced superoxide anion radical formation (confirmed through EPR analyses), and the combination of these reactive oxygen species (ROS) with ongoing solar radiation exposure enhanced bacterial inactivation. CIP enhanced the disinfection of antibiotic-resistant E. coli (by 1.84 log units at 120min of irradiation) and improved the inactivation of K. pneumoniae (by 3.48 log units at 135min)-both Gram-negative bacteria. Conversely, the photo-inactivation of the Gram-positive bacteria S. aureus did not significantly change (just a slight reduction of 0.42 log units at 120min) by the presence of CIP. Showing the bacterial structure influences the disinfection process. Another critical factor was antibiotic concentration. A high CIP concentration (10ppm) induced an interfering screen effect, while a low concentration promoted bacteria inactivation via photosensitization (in Gram-negative bacteria). Interestingly, no photosensitizing effect was observed when CIP was replaced by levofloxacin (LEV, another fluoroquinolone antibiotic), indicating a strong dependence on antibiotic structure. Additionally, the effect of the light source on photosensitized inactivation was evaluated, substituting sunlight with UVC irradiation. Under UVC light, CIP worsened ARB photo-inactivation, suggesting disinfection was mainly due to direct light action on microorganisms rather than photosensitization. Finally, the influence of water components on sunlight-photosensitized disinfection was examined using simulated urine and freshwater. The ARB inactivation decreased as matrix complexity increased. Thus, the effectiveness order was Milli-Q water > freshwater > urine.

A new indirect method for the quantification of total organic iodine (TOI) in environmental waters by inductively coupled plasma with mass spectrometry and liquid chromatography with tandem mass spectrometry.

The formation of emerging iodinated disinfection by-products (I-DBPs) is associated with iodine sources including organic compounds. Total organic iodine (TOI) was used as a bulk index of organic iodinated compounds because of the difficulty in identifying and quantifying individual organic iodinated compounds in environmental waters. Conventional methods for the direct quantification of TOI require complicated pretreatments, which has promoted many studies to attempt to simplify the quantification of TOI by an indirect measurement. In current indirect methods, TOI is mainly calculated as the differences between the concentration of total iodine (TI) and inorganic iodine (I- and [Formula: see text] ) by liquid chromatography-inductively coupled plasma with mass spectrometry (LC-ICP-MS). However, without accurate identification and discrimination by LC-ICP-MS, possible co-eluting iodinated compounds may be detected as I- and [Formula: see text] . To measure TOI more accurately, a simple method was developed by ICP-MS and liquid chromatography-tandem mass spectrometry (LC-MSMS). TI was measured by ICP-MS, and the spiked recoveries of tested iodinated compounds showed acceptable accuracy and repeatability in Milli-Q water and environmental waters, respectively. I- and [Formula: see text] were first simultaneously measured by LC-MSMS without redox pretreatments. The limits of quantification of I- and [Formula: see text] in this method were 0.05 μg I/L and 0.4 μg/L (0.3 μg I/L), respectively. The method is highly sensitive, and the actual concentration of I- and [Formula: see text] can be calculated by the spiked recovery. The method was successfully applied by measuring TOI concentration (2.2 to 17 μg I/L) in various types of environmental waters.

Assessing the Efficacy of Pyrolysis-Gas Chromatography-Mass Spectrometry for Nanoplastic and Microplastic Analysis in Human Blood.

Humans are constantly exposed to micro- and nanosized plastics (MNPs); however, there is still limited understanding of their fate within the body, partially due to limitations with current analytical techniques. The current study assessed the appropriateness of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) analysis for the quantification of a range of polymers in human blood. An extraction protocol that reduced matrix interferences (false positives) of polyethylene (PE) and polyvinyl chloride (PVC) was developed and validated. Extraction recoveries ranged 7-109%, although surface-modified polystyrene (carboxylated) increased nanoparticle recoveries from 17 to 52%. Realistic detection limits were calculated for each polymer, accounting for matrix suppression and extraction recovery. These were up to 20 times higher than nominal detection limits calculated with Milli-Q water. Finally, the method was tested with a pilot study of the Australian population. PE interferences were reduced but still present, and no other polymers were above detection limits. It was concluded that Py-GC-MS is currently not a suitable analysis method for PE and PVC in biological matrices due to the presence of interferences and nonspecific pyrolysis products. Furthermore, while it is plausible to detect some polymers in blood, the estimated exposure concentrations needed are approaching the detection limits of the technique.

Structure Matters: Tailored Graphitization of Carbon Dots Enhances Photocatalytic Performance.

The chemical structure and photoredox properties of carbon dots (CDs) are not yet fully understood. However, it has been reported that, by carefully choosing the starting materials and tuning their synthesis conditions, it is possible to obtain CDs with different chemical structures and therefore different photocatalytic performance. For this work, a family of different CDs was synthesized in Milli-Q water via a microwave-assisted protocol, using citric acid and urea as precursors. The syntheses were carried out at different times and temperatures to assess the impact of the synthetic parameters on the photocatalytic properties of the final materials. After extensive and accurate purification, the photocatalytic abilities of a selected subset of CDs were tested by performing a photocatalyzed atom transfer radical addition reaction. Among the tested CDs, the best performing ones were found to be those synthesized at the highest temperature, which were the most graphitic. A number of different characterization techniques were then used to evaluate the degree of graphitization of CDs and to elucidate the origin of their different photocatalytic performance.

Effect of Bovine Serum Albumin (BSA) Concentration on Cryopreservation of Booroolong Frog Sperm with Evaluation of Post-Thaw Motility in Caffeine.

Reproductive technologies, including sperm cryopreservation, offer conservationists enhanced capacity to genetically manage populations and improve the outcomes of conservation breeding programs (CBPs). Despite this potential, the post-thaw quality of amphibian sperm is highly variable following cryopreservation, and research focused on protocol refinement is needed. The aim of this study was twofold: (1) to investigate the effect of the addition of bovine serum albumin (BSA) to the cryopreservation medium (pre-freeze), and (2) the effect of the addition of caffeine to the activation medium (post-thaw), on post-thaw sperm characteristics in the critically endangered Booroolong frog (Litoria booroolongensis). Spermic urine samples were collected from 14 male frogs following hormonal induction of spermiation, and each sample was split among three cryopreservation treatments, where the cryopreservation medium contained either 0 (control), 0.5, or 1% BSA (w/v). Samples were cryopreserved and thawed, and sperm motility was then activated in one of two activation treatments: Milli-Q water (control) or Milli-Q water plus 4.5 mM caffeine. Sperm viability (proportion live/dead) was assessed using fluorescent microscopy, and sperm motility metrics were evaluated using computer-assisted sperm analysis (CASA). Results from this study showed that BSA concentration had no effect on post-thaw sperm viability. Additionally, neither BSA concentration nor activation in caffeine influenced post-thaw sperm motility characteristics (total motility, forward progressive motility, and velocity). Assessment time of sperm motility varied from 5 to 13 min post-activation and was significantly correlated with each motility measure, with motility and velocity metrics decreasing as time post-activation increased. The results reported herein provide no evidence for an effect of BSA or caffeine at the concentrations tested on post-thaw sperm characteristics in the Booroolong frog, but they highlight the time-sensitive nature of sperm assessment post-thaw and implications for the timing of sperm handling during assisted fertilisation efforts.

Novel, Rapid, and Simple Isocratic UPLC-UV Method for Estimating Nitrate and Nitrite Contents in Environmental Water Samples Using an Analytical Quality by Design Approach.

In this study, we reported a novel reverse-phase UPLC method for the simultaneous estimation of nitrite and nitrate ions using a Quality by Design (QbD) approach. Nitrite and nitrate ions were separated on an ACQUITY CSH Fluoro-Phenyl column (100 × 2.1 mm, 1.7 μm) in isocratic mode with a mobile phase composition of solvent A and solvent B in a ratio of 980:20 v/v. Solvent A consisted of 100% Milli-Q water, while solvent B comprised 0.5 mL of formic acid in 1000 mL of methanol. The column temperature was maintained at 40 °C, and the flow rate was 0.6 mL/min. Detection was carried out at 214 nm with an injection volume of 5.0 μL. The method was developed and validated in accordance with ICH Q2 (R2) guidelines Validation parameters, including system suitability, sensitivity, precision, linearity, and accuracy, were within acceptable ranges. These findings suggest that the developed RP-UPLC method is highly sensitive and suitable for the estimation of nitrite and nitrate ions in various environmental water samples.

Single but Not Combined In Vitro Exposure to Bisphenol A and Nanoplastics Affects the Cholinergic Function of the Ascidian Ciona robusta.

Nanoplastics are known to represent a threat to marine ecosystems. Their combination with other contaminants of emerging concerns (CECs) may amplify ecotoxic effects, with unknown impacts on marine biodiversity. This study investigates the effects, single and combined, of bisphenol A (BPA)-one of the most hazardous CECs-and polystyrene nanoparticles (PS NPs)-as a proxy for nanoplastics, being among the most commonly found asmarine debris-on cholinesterase (ChE) activities of the ascidian Ciona robusta. ChE activity was first measured in the siphons, tunic, and viscera of wild-caught adult specimens and exposed in vitro to BPA (0.01, 0.21, 0.69 mM) and PS NPs (0.0096-0.096 mM; 8.096 × 109-1010 particles, respectively) alone and combined for 15 min of incubation. PS NPs' behavior in milliQ water and in the ChE assay reaction buffer was characterized alone, combined with BPA, and analyzed through ζ-potential measurements via Dynamic Light Scattering. The results revealed that ChE activity was predominant in the viscera and siphons of C. robusta; PS NPs did not affect the ChE activity alone or combined, while BPA caused a concentration-dependent inhibition of ChE activity in the viscera. No changes in ζ-potential were observed for PS NPs alone or combined with BPA in the ChE buffer, suggesting no interaction. Further investigations are needed to understand the potential neurotoxic consequences for C. robusta and ecological risk scenarios due to exposure to BPA and nanoplastics in marine coastal waters.

Formulation and In Vitro Assessment of Tragacanth Gum-Based Hydrogel Loaded with Artemisia vestita Leaf Extract for Wound Healing

Artemisia vestita Wall. ex Besser, a traditional medicinal plant with healing properties, is receiving significant attention as a potential therapeutic agent for wound healing. In this study, eight Artemisia vestita leaf extract hydrogel formulations (F1–F8) were carefully designed and studied. The hydrogel formulations contained A. vestita leaf extract, tragacanth gum, humectants, preservatives, pH stabilizers, and Milli-Q water. A preformulation study was conducted to ensure safety and efficacy. Moreover, various experiments assessed the potential application and characteristics of A. vestita leaf extract hydrogel (ALEH). Drug release and swelling studies were conducted at different pH levels and temperatures. The best drug release model was identified based on the regression coefficient (R2). Antimicrobial efficacy was assessed using the agar well diffusion method, and wound healing in HaCat cells was assessed using the scratch assay. ALEH exhibited non-Fickian diffusion, with higher drug release noted at pH 6.8 than at pH 4.5, indicating pH-responsive behavior. It exhibited significant antimicrobial activity against various strains and achieved 95% wound closure after 24 h in vitro, indicating strong wound healing properties. It also had a long shelf life; therefore, it could have pharmaceutical and medical applications. Our study is the first to report the potential applications of ALEH in skincare and wound management.

Electrochemical Carbon Dioxide Reduction with Heteroatom Doped Ketjenblack Catalyst Using a Fuel Cell-Type Electrolytic Cell

IntroductionIn recent years, non-metallic catalysts with high efficiency for electrochemical carbon dioxide reduction have been reported and have attracted much attention. We have synthesized Ketjenblack® catalysts co-doped with nitrogen and sulfur by hydrothermal treatment of Ketjenblack and demonstrated their capability for the electrochemical carbon dioxide reduction. In this study, sulfur mono-doped Ketjenblack (S-KB) catalyst and nitrogen mono-doped Ketjenblack (N-KB) catalysts were synthesized and the electrochemical carbon dioxide reduction activity for the catalysts was evaluated using a fuel cell-type electrolytic cell. The S-KB catalyst was obtained by the hydrothermal treatment of Ketjenblack with ammonium sulfide, while the N-KB catalyst was prepared by heat treatment of Ketjenblack in a tube furnace under an ammonia atmosphere.Experimental Catalyst synthesis: 300 mg of Ketjenblack® (ECP600JD, LION) (KB) was mixed with 10 mL of 0.01 M sodium hydroxide solution, 10 mL of 2-propanol, 10 mL of ammonium sulfide solution (5.0~6.0 wt% as S) and 15 mL of Milli-Q® water. The mixture was hydrothermally treated in an autoclave vessel (TAF-SR300-SV, Taiatsu Techno Corp.) at 170°C. The product was ground in an agate mortar for about 3 min to obtain the S-doped catalyst (abbreviated as S-KB_processed time). Ketjenblack was heat-treated in a tube furnace under ammonia atmosphere for 60 min, quenched, and ground in an agate mortar for 3 min to obtain N-doped catalyst (abbreviated as N-KB_processed Temp. (℃)). Characterization was performed using X-ray photoelectron spectroscopy (PHI X Tool, ULVAC-PHI). Evaluation of CO2 reduction: To prepare catalyst inks, each prepared catalyst was mixed with 2-propanol, a 5 wt% Nafion® 2-propanol solution, Milli-Q water and zirconia balls, followed by shaking. The ink was then sprayed onto hydrophobic-treated carbon paper (TGP-H-060, Toray) at 1 mg cm−2. For the counter electrode, 38.1 wt% Pt/C (ISHIFUKU Metal Co., Ltd.) was sprayed onto carbon paper (without hydrophobic treatment) with 7 mm diameter holes (9.5 holes cm−2) at 1 mg cm−2. The carbon paper was hot-pressed onto a Nafion® membrane (NR-212, Dupont) at 135°C to form a membrane electrode assembly (MEA).The MEA was integrated into a fuel cell-type electrolysis cell, as shown in Fig. 1(a), with the working electrode side filled with 1 atm CO2, while the counter electrode side compartment was filled with 0.1 M phosphate buffer solution (pH 6). A tube-type RHE was used as a reference electrode (1). The electrolysis was performed at a constant potential of -1.0 V vs. RHE, and the qualitative determination of the products was performed by gas chromatographs (GC-8A, SHIMADZU) equipped with TCD and FID detectors.Results and discussionHeat treatment in a tubular furnace under ammonia flow resulted in the highest percentage of pyrrole-type nitrogen in N-KB_600 and pyridine-type nitrogen in N-KB_700. In S-KB_8h, sulfide-type was the most abundant. The carbon monoxide production rates of both sulfur-doped and nitrogen-doped catalysts were faster than those of pristine KB, suggesting their enhanced carbon dioxide reduction ability (Fig. 1(b)).References(1) Kunimatsu, H. Qiao and T. Okada, J. Electrochem. Soc., 5, 152 (2005). Figure 1

Development of Fe/N/C Type Oxygen Reduction Catalysts Using Carbon Supports Derived from Cellulose Paper by a Microwave Method

Introduction Effective utilization of abundant forest resources is crucial in Japan, which has vast forest reserves. Cellulose, which constitutes half of plants, has recently garnered attention as a novel material, such as cellulose nanofiber. Kyotani et al. reported that high-yield carbon materials retaining the original shape can be obtained by high-temperature treatment of cellulose-based paper treated with methanesulfonic acid1.We have been preparing Fe/N/C oxygen reduction catalysts using the carbon materials prepared by the method as a support; however, the oxygen reduction activity was insufficient. This study aimed to enhance the oxygen reduction reaction (ORR) activity by employing the microwave method for the preparation of carbon supports, synthesis of catalyst precursors, and drying treatment. Experimental Cellulose paper (toilet paper (TP), Nippon Paper Crecia) was immersed in 1.0 M methanesulfonic acid and air-dried for more than two days in a container with a filter attached to the top. The air-dried sample was sandwiched between two carbon plates, placed in an electric furnace, and heat-treated at 800°C for 1 h under Ar atmosphere with a heating rate of 5.5°C/min to obtain a carbonized sample. The sample was heat-treated using microwave oven (ER-SS17A, TOSHIBA) (denoted as MWtre). The sample was pulverized into carbon powder, mixed with 1,10-phenanthroline monohydrate, zinc acetate dihydrate, iron(II) acetate, and Milli-Q water, and heated and stirred for 30 min. Subsequently, the catalyst precursor slurry was obtained by heating using a microwave oven (RE-S5C-W, SHARP) (denoted as MWref). The obtained catalyst precursor slurry was dried using a microwave oven (ER-SS17A, TOSHIBA) to obtain the catalyst precursor (denoted as MWdry). The heat treatment was carried out in two stages. In the first stage, the catalyst precursor was placed in a SUS316 sealed container, replaced with Ar, heated to 800°C at 14°C/min, and then quenched to room temperature to prepare an intermediate material. In the second stage, the intermediate material was placed on a quartz boat and heat-treated at 1050°C for 20 min under Ar flow to obtain the catalyst.The oxygen reduction activity of the prepared catalyst was evaluated using the rotating ring-disk electrode (RRDE) method. A 2.00 mg/mL catalyst-2-propanol suspension, prepared by sonication and shaking, was cast on the GC electrode of a Pt ring-glassy carbon (GC) disk electrode (φ 6 mm), air-dried, and then 0.1 wt% Nafion® was cast and air-dried to prepare a catalyst-modified electrode. The evaluation of ORR activity was performed in 0.1 M sulfuric acid using the modified electrode as the working electrode, a GC electrode as the counter electrode, and RHE as the reference electrode. Results and discussion Fig. 1 shows the polarization curve and the efficiency of four-electron reduction (%H2O) obtained by the RRDE method. For comparison, the results for the catalyst prepared using the conventional method (refluxing for 24 hours followed by drying using a rotary evaporator) are also shown in Fig. 1 (quoted as EVAdry). The onset potential (@0.1 mA mg−1) derived from the oxygen reduction reaction was improved by 0.012 V compared to the conventional method. The efficiency of 4-electron reduction (@0.6 V vs. RHE) was improved by 8.9 – 21.1% compared to the conventional method. References (1) M. Kyotani, K. Hiratani, T. Okada, S. Matsushita, and K. Akagi, Global Challenges, 1, 1700061 (2017). Figure 1

Electrochemical Hydrogen Evolution Using Proton Transport through Graphene Monolayers

Pursuing sustainable hydrogen, electrochemical Hydrogen Evolution Reaction (HER) is crucial. However, challenges arise during HER, including the dissolution of catalytic materials and the formation of hydrogen bubbles on the electrode surface. Bubbles that evolve at an electrode may result in undesired blockage of the electrocatalytic surface, and ion conducting pathways in the electrolyte resulting energy losses1. Our study addresses this issue using monolayer graphene as a two-dimensional electrode with proton permeability.A graphene monolayer was synthesized using chemical vapor deposition (CVD) on a copper substrate. The fabrication process involved assembling the graphene monolayer on copper foil with nafion followed by hot pressing at 140°C for 2 minutes under 1.4 MPa pressure. Subsequently, this assembly was floated on Cu etchant (0.2 M (NH4)2S2O8 aqueous solution) facing Cu foil side overnight at 25°C and then rinsed Milli-Q water for several times. Platinum nanoparticles on graphene/nafion membrane was deposited using potential step method2. The electrochemical tests were carried out in 0.5 M H2SO4 vs RHE under argon (Ar) saturation using home-built electrochemical cell designed for proton permeable electrodes as illustrated Fig (a) and Cyclic voltammetry (CV) Fig (b) was performed Pt/Gr/N, Pt electrode at a scan rate of 50 mV/s.The hydrogen evolution performance of Pt/Gr/N measured in the proton permeable transport configuration in 0.5 M H2SO4 as evidenced by cyclic voltammetry revealing an observed lower overpotential of 17 mV at 10 mA/cm²(Pt-ECSA) suggests that proton transport occurs through the graphene layer, facilitating the hydrogen evolution reaction (HER) in gas phase without the generation of gas bubbles in electrolytes. This leads to minimal H2 reoxidation on Pt, which results in a positive shift in the observed onset potential and higher current density. On the other hand, Pt electrode in the conventional proton diffusion transport configuration exhibited a slightly higher overpotential of 28 mV at the same current density per Pt-ECSA, due to the HER in the solution phase. Indeed, hydrogen oxidation reaction (HOR) during the backward potential scan ofs the CV was observed only in the case of the conventional Pt electrode.1.Zhang C, Guo Z, Tian Y, et al. Nano Research Energy, 2: e9120063 (2023)2.Domínguez-Domínguez, et al. J Appl Electrochem 38:259–268 (2008) Figure 1

Insights into the characteristics and toxicity of microalgal biochar–derived dissolved organic matter by spectroscopy and machine learning

Microalgal biochar has potential applications in various fields; however, there is limited research on the properties and risks of microalgal biochar-derived dissolved organic matter (MBDOM). This study examined how different pyrolysis temperatures (200°C and 500°C) and extraction solutions (0.1mol/L HCl, Milli-Q water, and 0.1mol/L NaOH) affect the characteristics and toxicity of MBDOM from three microalgae using multi-spectroscopy methods. Results showed that higher pyrolysis temperature reduced dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) but increased total potassium (TK) in the MBDOM. Alkaline solution promoted DOC and TN dissolution, while acidic solutions enhanced TP and TK release from biochar. The molecular weight, aromaticity, and fluorescent composition of MBDOM varied based on pyrolysis temperature, extraction solution, and microalgae species. MBDOM from low pyrolysis temperature and alkaline extraction exhibited significant toxicity to Photobacterium phosphoreum T3. Correlation analysis and machine learning revealed that pyrolysis temperature had a greater influence on the characteristics and toxicity of MBDOM than the extraction solution. The toxicity of MBDOM was primarily associated with TN and DOC contents and also influenced by molecular weight, aromaticity, and humification. These findings are essential for optimizing microalgal biochar production and application.

Retention of nickel, cobalt and chromium in skin at conditions mimicking intense hand hygiene practices using water, soap, and hand-disinfectant in vitro

BackgroundDuring the COVID-19 pandemic, increased hand hygiene practices using water, soap and hand disinfectants, became prevalent, particularly among frontline workers. This study investigates the impact of these practices on the skin’s ability to retain the allergenic metals nickel, cobalt, and chromium. The study constitutes three parts: (I) creating an impaired skin barrier, (II) exposing treated and untreated skin to nickel alone, and (III) in co-exposure with cobalt and chromium.MethodsUsing full-thickness skin from stillborn piglets, in vitro experiments were conducted to assess retention of metals in skin at conditions mimicking intense hand hygiene practices. Treatment of skin with varying concentrations of sodium lauryl sulphate (SLS), to impair its barrier integrity was assessed. This was followed by exposure of treated and untreated skin to the metals, that were dissolved in Milli-Q water, 0.5% SLS, and ethanol respectively.ResultsResults showed that pre-treatment with 5% SLS impaired the skin barrier with regards to the measure of trans epidermal water loss (TEWL). Metal amounts retained in the skin were generally higher in treated than untreated skin. The highest amounts of metal retained in skin were observed for exposure to nickel in ethanol. Co-exposure to nickel, cobalt, and chromium in 0.5% SLS resulted in the highest amounts of total metal retention.ConclusionsThe in vitro findings highlight the increased risk of metal retention in skin due to an impaired barrier. The SLS concentration used in the current study corresponds to those used in many hand hygiene products. Hence, occupational settings with frequent exposure to water, soap and disinfectants need to consider protective measures not only for the irritant exposures themselves but also simultaneous exposure to allergenic metals.

Efficiency and ecotoxicity of activated biochar in the treatment of artificial wastewater contaminated by pharmaceuticals

Pharmaceuticals are emerging contaminants of global concern due to potential ecotoxicity and persistence in wastewater. Since conventional wastewater treatment plants are not designed to remove micropollutants and the removal efficiency varies compound-specifically, pharmaceuticals pose a risk in the recipient aquatic environments. Adsorption by solid materials such as activated biochar has been suggested to offer a practical removal method. However, not much is known about the environmental risks of the adsorbents used in wastewater treatment. This study aimed to study the efficiency of activated biochar (ACB) to remove low and high concentration of specific pharmaceuticals including diclofenac (DI), tetracycline (TE), and cephalexin (CEP) from Milli-Q water (MQ) and artificial wastewater (AWW). Furthermore, the study evaluated the ecotoxicity of these pharmaceuticals, as well as pristine ACB and ACB loaded with pharmaceuticals (ACB-LP), in both MQ and AWW using Daphnia magna. The adsorbate concentration and matrix affected ACB's removal efficiency. Weaker adsorbent-adsorbate interactions and mass transfer resistance at lower adsorbate concentrations, along with interactions between wastewater constituents and pharmaceuticals were the leading factors contributing to this reduction. These experimental observations indicate practical considerations for using adsorbents in operational wastewater settings. Furthermore, ACB-LPs generally exhibited lower toxicity compared to ACB, attributed to the saturation of free binding sites and reduced adhesion to daphnids. This study highlights the importance of examining the environmental risks of adsorbent materials used in wastewater treatment, particularly given their anticipated future use.

Charge as a key physicochemical factor in adsorption of organic micropollutants from wastewater effluent by rice husk bio-silica

Wastewater treatment plants (WWTPs) often fail to fully remove organic micro-pollutants (OMPs), necessitating advanced treatment methods. This study examines the potential of an agricultural waste-derived adsorbent, rice husk (RH) - silica, for removing a complex mixture of 20 OMPs in MilliQ water and wastewater effluent. While RH-silica shows potential for OMP removal, its performance with multicomponent mixtures in real wastewater has yet to be investigated. Batch experiments demonstrated the efficacy of RH-silica in removing cationic, neutral, polar, and non-polar OMPs across various pH levels, with no adsorption of anionic OMPs. Column elution studies revealed that only positively charged compounds did not reach a breakthrough after 300 specific bed volumes (BVs), even when the filtration velocity was increased fivefold (3.8 m/h) and lower adsorbent-to-volume ratios (0.5 g/L) were employed. This indicates that electrostatic interactions via deprotonated silanol groups are the primary adsorption mechanism. RH-silica's ability to retain cationic pollutants regardless of their hydrophilicity degree highlights its potential as a novel adsorbent targeting positively charged persistent and mobile organic compounds (PMOCs). Moreover, the adsorption efficiency remained high in experiments with real wastewater effluent. Considering practical applications, a RH-silica column could be used to enhance removal of cationic polar compounds. This approach not only improves pollutant removal efficiency but also contributes to sustainability in WWTPs by using agricultural waste resources. Despite significant operational and end-of-life challenges for large-scale implementation, this study represents a crucial advancement in the investigation of RH-silica as an adsorbent.

Impact of PM2.5 filter extraction solvent on oxidative potential and chemical analysis

ABSTRACT Fine particulate matter (PM2.5) is hypothesized to induce oxidative stress, and has been linked to acute and chronic adverse health effects. To better understand the risks and underlying mechanisms following exposure, PM2.5 is collected onto filters but prior to toxicological analysis, particles must be removed from filters. There is no standard method for filter extraction, which creates the possibility that the methods of extraction selected can alter the chemical composition and ultimately the biological implications. In this study, comparisons were made between extraction solvents (methanol (MeOH), dichloromethane (DCM), 0.9% saline, and Milli-Q water) and the results of oxidative potential and elemental concentration analysis of PM2.5 collected across sites in Arkansas, USA. Significant differences were observed between solvents, with DCM having significantly different results compared to all other extraction solvents (p ≤ 0.001). Significant correlations between element, black carbon, and PM2.5 concentrations and oxidative potential were observed. The observed correlations were extraction solvent dependent. For example, in saline extracted samples, oxidative potential had significant negative correlations with: Ba, Cd, Ce, Co, Ga, Mn and significant positive correlations with: Cr, Ni, Th, U. While in MeOH extracted samples, significant positive correlations were only between oxidative potential and Ga, U and significant negative correlations with V. This indicates that PM2.5 samples extracted with different solvents will yield different conclusions about the causal components. This study highlights the importance of filter extraction methods in interpretation of oxidative potential results and comparisons between studies. Implications: While there is no standard method for PM2.5 filter extraction, variation of extraction methods impact analytical results. This project identifies that extraction method variation, particularly extraction solvent selection, leads to discrepancies in chemical and toxicological analysis for PM2.5 collected on the same filter. This work highlights the need for methods standardization to support accurate comparisons between PM2.5 research studies, thus providing better understanding of PM2.5 across the globe.

Stability indicating RP-HPLC method development and validation for quantification of impurities in gonadotropin-releasing hormone (Elagolix): Robustness study by quality by design.

The purpose of this research was to establish and validate a reverse phase HPLC method for the determination of Elagolix impurities in pharmaceutical dosage form. Mobile phase A, consisting of 10mM sodium dihydrogen phosphate (pH6.0) and acetonitrile in a 95:5v/v ratio, and mobile phase B, containing 85:10:5v/v/v of acetonitrile, Milli-Q water, and methanol, were used to achieve the method's specificity in the analytical column Kromasil 100-C18 (250 mm × 4.6mm, 5μm). The gradient program includes (%B/Time [min]: 36/0, 36/10, 38/15, 85/55, 85/65, 36/67, and 36/75). The flow rate is 0.8mL/min. The overall run duration is 75.0min, the injection volume is 10.0μL, and the detection is at 210 nm in UV. The samples were subjected to hydrolysis, oxidation, and heat conditions in order to facilitate their forced degradation. The procedure was validated and determined with the standards of ICH guidelines. From the LOQ to a concentration level of 200%, the linearity of the technique was ascertained. An accuracy range of LOQ to 150% was established for the method, and the average recovery was acceptable. Design of experiments, part of the quality by design idea, was used to prove the method's reliability.

Potential amendments of coal fly ash-derived zeolite to beryllium contaminated soil at a legacy waste disposal site

Management of Be contamination using industrial solid waste or solid waste-derived amendments is not well understood. This study investigated the potential of Australian coal fly ash (CFA), derived synthesized zeolite (SynZ) and chitosan-modified zeolite (ModZ), for Be immobilization at the Little Forest Legacy Waste Site (LFLS), a low-level radioactive waste disposal site near Sydney, Australia. In laboratory simulation experiments, the SynZ and ModZ were separately applied as an amendment to both naturally contaminated soil and simulated contaminated (spiked) soil. Different techniques, including pore water (PW), batch desorption, and microbial activities were assessed to provide insight into immobilization mechanisms. Results revealed that amendment of 2% ModZ in soils, substantially decreased Be concentrations in PW (PWBe) ranging from 13.3% to 99.5% across all concentrations of Be. In contrast, PWBe increased while using SynZ, which could be attributed to the increased solubility of different organic-inorganic elements in PW. Moreover, batch desorption using Milli-Q water, simulated acid rainwater [H2SO4/HNO3=60/40, (v/v), and 0.11M acetic acid solution also revealed similar patterns of Be immobilization as found in PWBe analysis. Soil amendments boosted microbial biomass carbon, and phosphorous (MBC,P), along with basal respiration (BRCO2). This indicates increased microbial activities, which are linked with environmental eco-friendliness. This effect was substantially noticed in ModZ-amended soils, exhibiting up to 22 times higher in BRCO2 values compared to unamended soil. Additionally, reduced PWBe was correlated with soluble organic-inorganic elements, desorbed Be in the batch study, and soil MBc. The differences in behavior between SynZ and ModZ underline the importance of carefully studying the various potential amendment materials and the need to evaluate their performance before application in field situations. This study highlights ModZ's effectiveness in eco-friendly Be immobilization, underlining the role of organic functional groups in zeolite architecture, a key factor in controlling Be in soils.

Development and Validation of Selective and Sensitive Liquid Chromatography - Tandem Mass Spectroscopy (UHPLC-MS/MS) Method for Bioanalysis of Remogliflozin in Rat Plasma

Remogliflozin is an inhibitor of sodium-glucose cotransporter 2 inhibitors (SGLT-2) protein and plays an important role in the treatment and management of type-2 diabetes mellitus. In this study, a selective isocratic method was developed and validated using liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for the determination of remogliflozin in rat plasma. Acetonitrile with formic acid was used as a precipitating agent. Chromatographic separation was achieved by using X select CSH Fluorophenyl (150 mm x 4.6 mm, 3.5 µm) column and 0.1% formic acid in milli-Q water (20%) and acetonitrile (80%), v/v as a mobile phase for isocratic elution method. Flow rate and injection volume were maintained at 0.7 mL/min and 10 µL, respectively. The validated method was linear in the range of 15– 2009 ng/mL with the lower limit of quantification (LLOQ) of 18 ng/mL. Also, the method was precise with a % CV less than 5.75 and accuracy within ±10% of nominal concentration. The method is accurate, simple, precise, and suitable for its application in further bioequivalence and pharmacokinetic studies.