Alkaline Digestion Research Articles

In Vitro Oxidative Stress Threatening Maize Pollen Germination and Cytosolic Ca2+ Can Be Mitigated by Extracts of Emmer Wheatgrass Biofortified with Selenium.

In this work, we studied the effects of in vitro oxidative stress applied by H2O2 to maize pollen germination and cytosolic Ca2+, taken as an experimental model to test the biological activity of extracts of emmer (Triticum turgidum L. spp. dicoccum (Schrank ex Shubler) Thell.) wheatgrass obtained from grains sprouted with distilled water, or salinity (50 mM) or selenium (45 mg L−1 of Na2SeO3). Wheatgrass extracts were obtained in two ways: by direct extraction in methanol, which represented the free phenolic fraction of extracts (Ef), and by residual content after alkaline digestion, which made it possible to obtain extracts with the bound fraction (Eb). Comparative tests on maize pollen were carried out by differently combining H2O2 and either wheatgrass extracts or pure phenolic acids (4-HO benzoic, caffeic, p-coumaric and salicylic). The cytosolic Ca2+ of maize pollen was influenced by either H2O2 or pure phenolic acids or Ef, but not by Eb. The negative effect of H2O2 on maize pollen germination and cytosolic Ca2+ was mitigated by Ef and, slightly, by Eb. The extent of the biological response of Ef depended on the sprouting conditions (i.e., distilled water, salinity or selenium). The extracts of Se-biofortified wheatgrass were the most effective in counteracting the oxidative stress.

Ultrasound-assisted extraction of bound phenolic compounds from the residue of Apocynum venetum tea and their antioxidant activities

Bound phenolic compounds from the residue of Apocynum venetum (A. venetum) tea were released by alkaline digestion with sonication, followed by extraction using ethyl acetate (EtOAc). The fragment ions of compounds in free and bound forms were identified by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in both positive and negative modes. Further investigation of chemical constituents in the EtOAc extract led to the isolation of eleven individual compounds, and their chemical structures were identified as (−)-epicatechin (1), (−)-loliolide (2), (−)-syringaresinol-4-O-β-D-glucopyranoside (3), alloside of benzyl alcohol (4), 3-[(6-O-hexopyranosylhexopyranosyl)oxy]-2-(palmitoyloxy)propyl (9Z,12Z,15Z)-9,12,15-octadecatrienoate (5), apocynoside I (6), quercetin-3-O-β-D-glucopyranoside (7), kaempferol-3-O-β-D-glucopyranoside (8), [1-acetyloxy-3-[3,4,5-trihydroxy-6-[[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxymethyl]oxan-2-yl]oxypropan-2-yl] hexadecanoate (9), 1-stearoyl-2-palmitoyl-sn-glycerol (10), and 3-hexene-l-O-β-D-glucoside (11) using a series of spectroscopic methods. Compounds 2–5 and 9–11 were isolated for the first time from A. venetum, while antioxidant experiments showed that compounds 1, 7, and 8 displayed strong DPPH and ABTS + radical scavenging activities. This study represents the first investigation of bound phenolic compounds with potential health benefits in the residue of A. venetum tea.

High-efficiency mechanically assisted alkaline extraction of nanoparticles from biological tissues for spICP-MS analysis.

The widespread use and increased exposure of nanoparticles call for technology to quantify their concentration and size distribution in biological matrices. As ex situ evaluation, facile extraction with high fidelity and efficiency is critical. In this work, single particle inductively coupled plasma mass spectrometry (spICP-MS) was used for nanoparticle number and distribution analysis, where a facile and highly efficient mechanically assisted alkaline digestion has been developed to extract nanoparticles at low alkali concentration. The optimization was performed using chicken tissues in vitro mixed with 30nm gold nanoparticles, mixture of 30nm and 60nm gold nanoparticles, and 45nm silver nanoparticles, respectively, which is, then, mechanically ground to form tissue homogenate and 2% TMAH is added. The nanoparticles are extracted with a recovery of more than 94% for all the spiked nanoparticle tissue samples. The extraction method has also been attempted to be applied to extract single-sized gold nanoparticles from various organs of mice mixed in vivo with the nanoparticles through intravenous injection, and led to consistent results with acid digestion. Mice injected intravenously with double-sized gold nanoparticle mixture were also studied, further showing that gold nanoparticles of 30nm and 60nm have no significant difference in their biodistribution in the same organ. To the best of our knowledge, this is the first attempt for multiple nanoparticles being extracted simultaneously and measured quantitatively from various organs, such as the heart, liver, spleen, lungs, and kidneys. We believe this method is beneficial to the safetyassessment and toxicokinetics studies for nanoparticles in tissues.

The role of mesopelagic fishes as microplastics vectors across the deep-sea layers from the Southwestern Tropical Atlantic

Microplastics (MPs; <5 mm) are a macro issue recognised worldwide as a threat to biodiversity and ecosystems. Widely distributed in marine ecosystems, MPs have already been found in the deep-sea environment. However, there is little information on ecological mechanisms driving MP uptake by deep-sea species. For the first time, this study generates data on MP contamination in mesopelagic fishes from the Southwestern Tropical Atlantic (SWTA) to help understand the deep-sea contamination patterns. An alkaline digestion protocol was applied to extract MPs from the digestive tract of four mesopelagic fish species: Argyropelecus sladeni, Sternoptyx diaphana (Sternoptychidae), Diaphus brachycephalus, and Hygophum taaningi (Myctophidae). A total of 213 particles were recovered from 170 specimens, and MPs were found in 67% of the specimens. Fibres were the most common shape found in all species, whereas polyamide, polyethylene, and polyethylene terephthalate were the most frequent polymers. The most contaminated species was A. sladeni (93%), and the least contaminated was S. diaphana (45%). Interestingly, individuals caught in the lower mesopelagic zone (500–1000 m depth) were less contaminated with MPs than those captured in the upper mesopelagic layer (200–500 m). Our results highlight significant contamination levels and reveal the influence of mesopelagic fishes on MPs transport in the deep waters of the SWTA.

Tissue engineering of human ear pinna.

Auricular deformities (Microtia) can cause physical, social as well as psychological impacts on a patient's wellbeing. Biofabrication of a complex structure such as ear pinna is not precise with currently available techniques. These limitations can be overcome with the help of tissue engineering. In this article, the authors presented molding and three dimensional (3D) printing to generate a flexible, human size ear pinna. The decellularization of goat ear cartilage protocol and bioink alkaline digestion protocol was followed to yield complete removal of all cellular components without changing the properties of the Extra Cellular Matrix (ECM). Decellularized scaffold used in molding technology and 3D printing technology Computer-Aided Design /Stereolithography (CAD/STL) uses bioink to construct the patient-specific ear. In vivo biocompatibility of the both ear pinnae showed demonstrable recellularization. Histology and scanning electron microscopy analysis revealed the recellularization of cartilage-specific cells and the development of ECM in molded and 3D printed ear pinna after transplantation. Both the techniques provided ideal results for mechanical properties such as elasticity. Vascular Associated Protein expression revealed specific vasculogenic pattern (angiogenesis) in transplanted molded pinna. Chondrocyte specific progenitor cells express CD90+ which highlighted newly developed chondrocytes in both the grafts which indicated that the xenograft was accepted by the rat. Transplantation of molded as well as 3D ear pinna was successful in an animal model and can be available for clinical treatments as a medical object to cure auricular deformities.

Dietary exposure of zinc oxide nanoparticles (ZnO-NPs) from canned seafood by single particle ICP-MS: Balancing of risks and benefits for human health

The present study aims to give information regarding the quantification of ZnO-NPs in canned seafood, which may be intentionally or unintentionally added, and to provide a first esteem of dietary exposure. Samples were subjected to an alkaline digestion and assessment of ZnO-NPs was performed by the single particle ICP-MS technique. ZnO-NPs were found with concentrations range from 0.003 to 0.010 mg/kg and a size mean range from 61.3 and 78.6 nm. It was not observed a clear bioaccumulation trend according to trophic level and size of seafood species, although the mollusk species has slightly higher concentrations and larger size. The number of ZnO-NPs/g does not differ significantly among food samples, observing an average range of 5.51 × 106 - 9.97 × 106. Dissolved Zn determined with spICP-MS revealed comparable concentration to total Zn determined with ICP-MS in standard mode, confirming the efficiency of alkaline digestion on the extraction of the Zn. The same accumulation trend found for ZnO-NPs was observed more clearly for dissolved Zn. The ZnO-NPs intake derived from a meal does not differ significantly among seafood products and it ranges from 0.010 to 0.031 µg/kg b.w. in adult, and from 0.022 to 0.067 µg/kg b.w. in child. Conversely, the intake of dissolved Zn is significantly higher if it is assumed a meal of mollusks versus the fish products, with values of 109.3 µg/kg b.w. for adult and 240.1 µg/kg b.w. for child. Our findings revealed that ZnO-NPs have the potential to bioaccumulate in marine organisms, and seafood could be an important uptake route of ZnO-NPs. These results could be a first important step to understand the ZnO-NPs human dietary exposure, but the characterization and quantification of ZnO-NPs is necessary for a large number of food items

Simultaneous Determination of Fluorine and Chlorine in Marine and Stream Sediment by Ion Chromatography Combined with Alkaline Digestion in a Bomb

Fluorine and chlorine are important tracers for geochemical and environmental studies. In this study, a rapid alkaline digestion (NaOH) method for the simultaneous determination of fluorine and chlorine in marine and stream sediment reference samples using ion chromatography is developed. The proposed method suppresses the volatilization loss of fluorine and chlorine and decreases the matrix effects. The results are in good agreement with fluorine ~100%, chlorine ranging from 90 to 95% of the expected concentrations. The detection limits of this method were 0.05 μg/g for fluorine and 0.10 μg/g for chlorine. This method is simple, economical, precise and accurate, which shows great potential for the rapid simultaneous determination of fluorine and chlorine in large batches of geological and environmental samples commonly analyzed for environmental geochemistry studies.

Evaluation of ZnO-NPs in canned seafood by single particle ICP-MS determination

Abstract Zinc is a well-known essential micronutrient, widely used as a food supplement, antimicrobial agent and food preservation. NOAEL was established at 50 mg/person per day and an upper limit of 25 mg/person per day was recommended. ZnONPs are GRAS substances approved by FDA. Nanotechnology is an emerging issue because of the industrial widespread use of ZnO nanoparticles and their potential toxicity and bioaccumulation. Aim of this study is to provide information regarding the quantification of ZnO-NPs, which may be intentionally or unintentionally added, in different brands of canned tuna (CT) and canned clam (CC), and to provide a first esteem of dietary exposure. Canned seafood was subjected to an alkaline digestion with TMAH. Assessment of ZnONPs was performed using a NexION 350D with the Syngistix Nano Application software (Perkin Elmer), allowing to identify number of particles, size and size distribution of metal NPs with the simultaneous quantification of the dissolved elemental concentration. Estimated Meal Intake was evaluated for adults by assuming a meal size of 227 g, 70 years old and 70 Kg of b.w. Results revealed a comparable mean size range between the considered food item (CT 69-80 nm; CC 75-83 nm). Concentration of ZnONPs are significantly higher in CC versus CT (CT 3.2-9.8 µg/Kg; CC 7.7-11.3 µg/Kg). The same we found for dissolved Zn concentration (CT 19.1-28.4 mg/Kg; CC 27.4-39.2 mg/Kg). For CT it was estimated an EMI of 0.018 µg/Kg bw for ZnONPs and 79.9 µg/Kg bw for dissolved Zn. For CC it was estimated an EMI of 0.031 µg/Kg bw for ZnONPs and 109 µg/Kg bw for dissolved Zn. Our findings revealed that ZnO-NPs have the potential to bioaccumulate in marine organisms, and seafood could be an important uptake route of ZnONPs. These results are a first important step to understand the ZnONPs human dietary exposure, but the characterization and quantification of ZnONPs is necessary for a large number of food items. Key messages The extensive use and discharge of ZnONPs will probably expose human population to concentration higher than the recommended upper limit 25 mg/person per day. The quantification of ZnONPs dietary exposure will be useful for risk assessors in developing provisional tolerable daily intake.

Interfering elements on determination of hexavalent chromium in paper materials with UV-vis spectrophotometry

Abstract Regulation of hexavalent chromium is based on Waste Framework Directive 1994/62/EC, European Commission and publication of the World Health Organization. Herein, detection of hexavalent chromium was performed by alkaline digestion and instrumental analysis which was demonstrated in USEPA methods. However, UV-vis detection method could be affected by some metal ions reacted with diphenylcarbizide. Actually, various interfering elements, such as Ni, Fe, Al, and Cu, were detected and selected by ED-XRF in paper materials. In order to improve accuracy of analysis results of hexavalent chromium in paper materials based on USEPA methods, the interfering elements was removed by liquid–liquid extraction with carbonate media using tricaprylmethylammonium chloride and chloroform after alkaline digestion. Consequently, the temperature for alkaline digestion was between 85 and 95 °C. Hydrochloric acid was proper complex tricaprylmethylammonium-Cr(VI) in the procedure of liquid extraction. After that hexavalent chromium was completely extracted using of 1 M sodium hydroxide solution. The technique for analyzing the hexavalent chromium used in liquid–liquid extraction significantly reduced the errors caused by the interfering elements, Fe and Cu. Thus, application of the extraction method was efficient in removing the interfering elements, which increased the recovery ratio of the hexavalent chromium from paper materials by 90 %.

Sensitive determination of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol and complementary cannabinoids in hair using alkaline digestion and mixed-mode solid phase extraction followed by liquid-chromatography-tandem mass spectrometry

Hair drug testing can be used for the evaluation of cannabis use with a large detection window, and is required for professional driving license granting in Brazil. A positive hair result for cannabis use requires quantification of the metabolite THC-COOH above the cutoff value of 0.2 ng/g. The achievement of such lower limit of quantification is challenging, particularly with the use of liquid chromatography coupled to triple quadrupole mass spectrometers (LC-MS/MS). In this study, a very sensitive LCMS/ MS assay for the simultaneous quantification of THC-COOH along with THC, CBD, and CBN was developed and validated. Sample preparation was based on hair hydrolysis, followed by selective ion-exchange solid-phase extraction. The extraction yield was 101.5–101.6% for THC-COOH, 92.3–97.4% for THC, 89.7–95.2% for CBN, and 104.9–121.1% for CBD. Internal standard corrected matrix effects were − 2.7 to − 1,1 for THCCOOH and − 11.5 to − 0.1% for the other analytes. The lower limit of quantification was 01 ng/g for THC-COOH and 25 ng/g for THC, CBD, and CBN. The assay fulfilled validation guidelines acceptance criteria. The measurement uncertainties were determined and the assay was ISO17025 accredited, being currently used in routine testing.

Asymptotic modeling of electrochemical signaling: Testing Zn in urine for non-invasive bladder cancer diagnosis

A theoretical model on chemical signaling for diagnosis based on the combination of signals for marker and inert and/or interfering metabolites is described. The model yields asymptotic relationships between the intensities of the signals representative of marker and accompanying metabolites compensating concentration fluctuations. The model fits well with voltammetric features associated to the oxidation of different urine metabolites and Zn(II) reduction in the same urine samples after alkaline digestion. As a result, a non-invasive electrochemical detection of urothelial carcinoma (bladder cancer, BC) is reported. Different diagnostic criteria are described all displaying high sensitivity, specificity and positive/negative predictive values. The described methodology was tested by means of an analytical trial with 46 patients with histological and pathologically confirmed BC, 30 healthy controls and 26 patients diagnosed of other urinary pathologies,

Role of nearshore benthic algae in the Lake Michigan silica cycle.

Si cycling is linked with processes from global carbon sequestration to community composition and is especially important in aquatic ecosystems. Lake Michigan has seen dramatic fluctuations in dissolved silica (dSi) over several decades, which have been examined in the context of planktonic processes (diatom blooms), but the role of benthic organisms (macroalgae and their epiphytes) in Si cycling have not been explored. To assess significance of nearshore benthic algae in Si dynamics, we assembled dSi data from an offshore site sampled since the late 1980’s, and sampled off three Milwaukee beaches during 2005–19. Using colorimetric assays and alkaline digestion, we measured dSi, biogenic silica in particulate suspended material (pSi) and biogenic silica in benthic macroalgae (Cladophora) and epiphytic diatoms (bSi). Offshore, dSi increased about 1 μM per year from 25 μM in the late 1980’s to nearly 40 μM in 2019. Nearshore dSi fluctuated dramatically annually, from near zero to concentrations similar to offshore. Both Cladophora and its epiphytes contained significant bSi, reaching up to 30% of dry mass (300 mg Si g dry mass-1) of the assemblage in summer. Microscopic analyses including localization with a Si-specific-stain and X-ray microanalysis showed bSi in epiphytic diatom cells walls, but the nature and localization of Si in macroalgae remained unclear. A simple model was developed estimating Si demand of algae using the areal macroalgal biomass, growth rates inferred from P-content, and bSi content, and comparing Si demand with dSi available in the water column. This indicated that 7–70% of the dSi in water overlying nearshore benthic algal beds could be removed per day. Key elements of the Si cycle, including which organisms sequester bSi and how rapidly Si is recycled, remain unclear. This work has implications for coastal marine waters where large macroalgal biomass accumulates but bSi content is virtually unknown.

Microplastic extraction protocols can impact the polymer structure

Although microplastics are ubiquitous in today’s natural environments, our understanding of the materials, quantities, and particle sizes involved remains limited. The recovery of microplastics from different types of environmental matrices requires standardized matrix digestion protocols that allow inter-laboratory comparisons and that have no effect on the polymers themselves. A number of commonly used digestion methods rely on oxidation with concentrated hydrogen peroxide solutions to remove organic matter from the matrix. However, this can alter the nature of polymers through hydrolysis and often does not lead to a complete matrix removal. We have therefore investigated the use of two altered matrix digestion protocols, an acidic (Fenton) protocol and a new alkaline (Basic Piranha) protocol, focusing mainly on the effect on biodegradable polymers (polylactide, polybutylene adipate terephthalate, polybutylene succinate) and polymers with known degradation pathways via hydrolysis (thermoplastic polyurethanes, polyamide). Comparing the initial surface textures, chemical compositions, and particle size distributions with those obtained after digestion revealed that the Fenton protocol left most of the polymers unchanged. The ferrous residue that remains following Fenton digestion had no effect on either the polymer composition or the particle size distribution, but could disturb further analytics (e.g. Raman microscopy due to auto-fluorescence). While increasing the chance of complete matrix removal, the more powerful Basic Piranha protocol is also more likely to affect the polymer properties: Polylactide polymers in particular showed signs of degradation under alkaline digestion (reduced polylactide content, holes in the polymer matrix), indicating the unsuitability of the Basic Piranha protocol in this specific case. Polyamide, however, remained stable during the Basic Piranha treatment, and the surface chemistry, the particle size as well as the molar mass distribution of the investigated thermoplastic polyurethanes were also not affected. Hence, this protocol offers a powerful alternative for microplastic analysis with focus on particle size in more complex environmental matrices (e.g. removal of cellulose in soil), while avoiding ferrous Fenton residue. Unexpectedly, also tire rubber, a frequent target analyte in microplastic monitoring, was found to be susceptible to artefact structures by both oxidation protocols. In summary, controls for the specific combination of polymer and sample preparation protocol are highly recommended to select the most fitting protocol. Here selected suitable combinations are reported.

Assessing microplastic distribution within infaunal benthic communities in a coastal embayment

Marine anthropogenic litter is increasing in prevalence in both the marine environment and its inhabitants. This study assesses the levels of anthropogenic microplastics in benthic infauna from 20 subtidal stations in Galway Bay, Ireland. Microplastics were removed from the organisms using an alkaline digestion (KOH) and their synthetic origin was confirmed by μFTIR spectroscopic analysis. The average number of microplastics recorded for all organisms was 0.79 ± 1.14 particles individual−1, similar to previously published results on subtidal fauna of the North Sea. Fibres were the dominant particle type (98%) and the majority were identified as natural (cellulose, cotton). Synthetic polymers identified included PVA (polyvinyl acetate), EPDM (synthetic rubber), PE (polyethylene) and PVC (polyvinyl chloride). Fibres less than 1 mm made up 55% of the recovered lengths. Colours recorded in the organisms were mainly blue and were reflective of the surrounding habitats. Of the five phyla collected, the highest incidence and uptake was associated with the Annelida. A significant difference in ingested MPs was only evident when depth (greater and less than 30 m) was considered as a factor. In addition, no significant differences were found between either the numbers of ingested MPs and phyla or feeding strategies. The results indicate that future studies should follow an ecosystem-based approach to monitor MPs levels in an area where specific bioindicator(s) have not been identified or are unsuitable.

Incidence of Watershed Land Use on the Consumption of Meso and Microplastics by Fish Communities in Uruguayan Lowland Streams

Physical-chemical and biologicaldiversity of streams are influenced by the land use in their watersheds. Plastics currently make up the most important waste asset, representing an important part of the transported and accumulated material in water courses. This work analyzes the consumption of plastics debris by the fish communities in streams with two contrasting types of land use. We worked with threestreams impacted by urbanization and threeby extensive ranching. The stomach and intestinal contents of 309 individuals of 29 species were analyzed, by a modified alkaline digestion, and observed under a stereo microscope with polarized light. A total of 373 plastic itemswere found, of which the majority corresponded to fibers (318). A significant difference was found between the percentage of individuals that consumed plastic debrisbetween both systems (51.6% in ranchers and 76.6% in urban, p = 0.014 Mood’s Median), but no difference was found in the average ingested per individual. This study establishes the first baseline on plastic debris consumption by fish in Uruguayan streams, showing the extent of the plastic and microplastic pollution problem. Although there are differences between the analyzed sites, we also observed significant contamination in streams far from urbanization.

Evaluation of remediation of Cr(VI)-contaminated soils by calcium polysulfide: Long-term stabilization and mechanism studies

In the remediation of Cr(VI)-contaminated soils, the effectiveness and long-term stability are critical qualities for the selection of a reductant. In current engineering practices, iron-based materials and sulfides are the most prevalent reductants, and calcium polysulfide (CaS4) is considered as the one with the highest effectiveness and strongest long-term stabilization ability. But this opinion is questioned by the high interference ability of CaS4 to soil Cr(VI) analysis. This study provides a pretreatment method to eliminate the interference of residual ferrous and sulfides to soil Cr(VI) analysis. By this pretreatment method and comparing with FeSO4 and Na2S, the mechanisms of the false high effectiveness and strong long-term stabilization ability of CaS4 is revealed. In the remediation process, CaS4 produces much elemental sulfur (S0) which remains in the soils. During the alkaline digestion, the S0 generates polysulfide which reduces the extracted Cr(VI), inducing serious negative analysis bias. When this negative bias is eliminated by pretreatment method, analysis results show that CaS4 exhibits lowest effectiveness. The S0 cannot be leached away from soils and oxidized by oxygen under natural conditions, this makes CaS4 exhibit a persistent interference ability, which is mistaken for a strong long-term stabilization ability.

Detection of 6-monoacetylemorphine in hair sample of heroin addicts using gas chromatography\u2013mass spectrometry and significance of rehabilitation program

BackgroundThe analysis of hair samples for the detection of drugs has become one of the convincing strategies in the field of forensic toxicology. A large number of cases concerning heroin abuse or its byproducts have been documented under the Control of Narcotic Substances Act, 1997, over the past decade. The present study was carried out with an aim to evaluate the primary metabolite of heroin, i.e., 6-monoacetylemorphine (6-MAM), in hair samples of addicts and subjects undergoing rehabilitation, thereafter accessing the success rate of the rehabilitation program at the de-addiction center.ResultsHair samples were randomly collected from 20 regular heroin addicts and 20 heroin addicts from their past, from the rehabilitation center, of different age groups. Samples were cleaned, digested, and extracted using an alkaline digestion mediator methyl tertiary butyl ether, followed by quantification of 6-MAM via gas chromatography–mass spectrometry (GC–MS). The mean concentration of 6-MAM in regular heroin addicts detected was 7.80 ng/mg and 2.34 ng/mg in samples of subjects undergoing rehabilitation at the de-addiction center, respectively.ConclusionTraces of 6-MAM in the hair sample of heroin addicts can be efficiently detected days after the last intake of heroin. In addition to that, our findings also give an idea for future evaluating the approximate timeframe for detection of 6-MAM and/or other metabolites of heroin in the hair sample. However, in the future, by carefully analyzing the hair samples that can be taken from rehabilitation centers from target subjects at different time intervals, the exact duration of traceable quantity of 6-MAM can be determined in the hair sample. Finally, it can be concluded that there is a significant success rate of the rehabilitation program at de-addiction centers in connection with dragging the 6-MAM level from the body.

Development of a fast and efficient method to analyze microplastics in planktonic samples

Microplastics (MPs) affect plankton (a basis of the trophic chain) and planktivorous fish can ingest them through food confusion or by trophic transmission. Consensus to determine MPs in plankton is lacking and, so, three digestion treatments were evaluated: Alkaline (potassium hydroxide) and enzymatic (protease plus lipase) digestions, both combined with a hydrogen peroxide stage; and an oxidative method using a surfactant (sodium dodecyl sulfate) plus hydrogen peroxide. The alkaline method using potassium hydroxide was found to damage polystyrene. MPs were identified with a stereomicroscope and characterized by reflectance infrared microscopy in semi-automatic mode (using dedicated multi-well aluminium plates). Analytical recoveries for polypropylene, polystyrene, polyethylene, polyamide, polyvinyl chloride and polyethylene terephthalate were higher than 75%, 82% and 83% for the alkaline, enzymatic and oxidative treatments, respectively. The enzymatic method was successfully validated in a European interlaboratory exercise and the oxidative method was demonstrated to be a reliable, fast and cheaper alternative.

Major characteristics of microplastics in mussels from the Portuguese coast

The present study reports the quantity, shape, colour and chemical properties of microplastics (MP) and MP-like in whole soft tissues of the mussel Mytilus spp. collected in January and February 2019 from four natural banks in the Portuguese coast. Three sites are located in estuarine areas influenced by anthropogenic pressures and freshwater discharges, and one in the coast far from urbanised areas. An alkaline digestion (KOH) of biological tissues was used and a polymeric identification of 20% of the visually sorted particles was achieved using the Fourier-transform mid-infrared spectroscopy (FT-MIR). MP and MP-like concentrations ranged from 0.54 to 3.0 items g−1 without significant differences among the sites. Particle size varied from 36 to 4439 μm, being fibers the most abundant shape (50%) followed by films (22%) and spherules (18%). FT-MIR revealed that 69% of the analysed particles were plastic, being identified six polymers and two polymeric blends, and 32% were cellulose-based materials. Fibers identified in mussel tissues were mainly composed of cotton and viscose (77%). This study emphasizes the importance of the polymer's spectroscopic identification after microscopic observation to recognise MP.

Evaluation of plasma cleaning as an approach for the preparation of soil minerals for forensic comparison by photon and electron microscopy.

Although organic material is often used for forensic analysis, a substantial portion of the data gathered for determination of common origin of forensic soil samples is the inorganic, mineralogical composition of the sample, which may be obscured by the presence of soil organic material (SOM). Traditionally, SOM is removed by acidic, alkaline, or peroxide digest, or by combustion, but these techniques risk the damage to or destruction of target minerals of interest. Low-temperature plasma ashing, on the other hand, removes organic materials by exposing them to plasma ions with high-kinetic energy, converting organics to easily removed volatile products (CO, CO2 , H2 O, or methane) while avoiding the thermal alterations caused by heat combustion. This study exposed grains of known mineral types to 20min of a low-pressure O2 plasma generated by a 10MHz frequency generator. Powder x-ray diffraction was chosen as an independent method to evaluate the minerals for chemical or structural changes caused by this ashing process. Side-by-side comparison of before and after diffractograms revealed minimal, if any, variation in the detected 2θ and subsequently calculated d-spacing: differences in d values were found to generally be less than 1%, and most were within Hanawalt Search Index uncertainties by no less than a full order of magnitude. Peak intensity changes were similarly minimal. This study strongly suggests that low-temperature plasma ashing can be used for the isolation of inorganic soil material fraction for forensic soil analysis with little or no concern for potential alteration of the mineral grains.