Ultrasound-assisted Procedure Research Articles

Development of a green ultrasound-assisted procedure for the extraction of phenolic compounds from avocado peel with deep eutectic solvents

Avocado (Persea americana Mill.) is a tropical fruit grown in different areas of the world. Avocado pulp is of interest to food companies while seed and peel are wasted. In 2021, about 25 thousand tons of avocado peel were produced as waste. In accordance with circular economy and green chemistry principles, avocado peel could be considered a source of bioactive molecules, specifically phenolic compounds, to be recovered using green methods. Deep eutectic solvents (DESs) are green solvents whose extractive efficiency for phenolic compounds from food and waste products of the agri-food chain has already been demonstrated. In this work, an ultrasound-assisted solid-liquid extraction, using DESs, was developed to recover phenolic compounds from avocado (Hass variety) peel. For this purpose, twelve DESs were tested as extraction solvents considering the provided total phenolic content. Then, in order to obtain the largest amount of phenolic compounds, the most relevant factors affecting solid-liquid extraction were evaluated. Matrix-to-solvent ratio of 1:30 (w/v), 25°C and 15 min as temperature and time of extraction, respectively, were found as optimal conditions to guarantee an extracted amount of phenolic compounds of 8.29 ± 0.07 g GAE/100g of dry avocado peel. Through high-performance liquid chromatography coupled with photodiode array and mass spectrometry detection, some flavonoids and phenolic acids were identified in the avocado peel extract.

Response Surface Methodology as an Experimental Strategy for Ultrasound-Assisted Extraction of Phenolic Compounds from Artichoke Heads.

The accurate quantification of phenolic compounds (PCs) in foods has become mandatory for a reliable estimation of PCs dietary intake. However, the extraction step of these molecules from the food matrix is a challenging and complex task. To manage the current lack of an official or generally accepted procedure for the recovery of phenolics, the application of statistical and mathematical tools, such as the response surface methodology (RSM), that allow the optimization of extraction parameters and the acquisition of the best output, has become the analytical approach of choice. The aim of this study was to apply an RSM-optimized ultrasound-assisted procedure to extract phenolic compounds from artichoke (Cynara cardunculus L. var. scolymus (L.) Hegi, cultivar "Campagnano") heads. The effect of extraction time, temperature, and solvent-to-sample ratio on the profile and content of phenolic acids and flavonoids was investigated. The total phenolic content was 488.13 ± 0.56 mg GAE 100 g-1 dry matter (dm) and total flavonoid content was 375.03 ± 1.49 mg CATeq 100 g-1 dm when the optimum extraction conditions were set. The HPLC analysis showed that caffeoylquinic acid derivatives (i.e., cynarin and 1,5-O-dicaffeoylquinic acid) were the main compounds in globe artichokes. Caffeic and p-coumaric acids were also identified. In regard to flavonoids, only the flavone luteolin-7-O-glucoside was identified.

Ag/Ag3PO4 Nanoparticle-Decorated Hydroxyapatite Functionalized Calcium Carbonate: Ultrasound-Assisted Sustainable Synthesis, Characterization, and Antimicrobial Activity

Silver nanoparticles are usually prepared by the reduction of silver cations through chemical and non-sustainable procedures that involve the use of reducing chemical agents. Therefore, many efforts have been made in the search for sustainable alternative methods. Among them, an ultrasound-assisted procedure could be a suitable and sustainable method to afford well-dispersed and nanometric silver particles. This paper describes a sustainable, ultrasound-assisted method using citrate as a reducing agent to prepare silver@hydroxyapatite functionalized calcium carbonate composites. For comparison, an ultrasound-assisted reduction was performed in the presence of NaBH4. The composites obtained in the presence of these two different reducing agents were compared in terms of nanoparticle nature, antimicrobial activity, and cytotoxic activity. The nanoparticle nature was investigated by several techniques, including X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy, UV-Vis spectroscopic measurements, and X-ray photoemission spectroscopy. Nanoparticles with a predominance of Ag or Ag3PO4 were obtained according to the type of reducing agent used. All composites were tested for antimicrobial and antibiofilm activities against Gram-positive and Gram-negative (Staphylococcus aureus and Pseudomonas aeruginosa, respectively) bacteria and for cytotoxicity towards human skin keratinocytes and human fibroblasts. The nature of the nanoparticles, Ag or Ag3PO4, and their predominance seemed to affect the in vitro silver release and the antimicrobial and antibiofilm activities. The composites obtained by the citrate-assisted reduction gave rise to the best results.

Ultrasound-Assisted Demineralization Process of Sugarcane Straw and Its Influence on the Further Biomass Conversion

Lignocellulosic materials have been considered as an alternative source from which liquid biofuel and fine chemicals can be produced with a moderate environmental impact. However, they can be contaminated with metals, soil, and ash, owing incrustation and corrosion of industrial reactors and pipelines. In this work, the use of ultrasound energy was applied for the removal of metals and nonmetals (Ba, Ca, Mg, Mn, P, S, Si, and Sr) from sugarcane straw. Ultrasound-assisted demineralization (UAD) experiments were carried out in ultrasonic baths in several frequencies (from 25 up to 130 kHz). The following experimental conditions were evaluated: demineralization solution (HNO3, HCl, H2SO4, H2O2, and H2O), H2O2 concentration (from 5 to 30% v v−1), extraction temperature (from 30 to 70 °C), sonication time (from 5 to 45 min), and ultrasound amplitude (from 10 to 70%). Better demineralization efficiencies (66%) were obtained employing an ultrasound bath operating at 25 kHz for 30 min, ultrasound amplitude of 60%, and using a diluted H2O2 solution (15% v v−1) at 70 °C. When the obtained results were compared with those obtained by mechanical stirring (MS, 500 rpm), it was observed that the use of ultrasound energy increased the demineralization efficiency up to 16%. Furthermore, acid hydrolysis was performed to evaluate the influence of US and mechanical stirring in fermentable sugars’ production. The total sugars’ yield (glucose, xylose, and arabinose) increased around 55% for both systems (US and MS). To prove the applicability of the proposed process, some experiments for scaling up were performed using several reaction loads (0.5 to 3 L). An attempt for scaling the proposed process up was well succeeded up to a 3 L load. Therefore, the proposed ultrasound-assisted procedure can be considered as a suitable alternative for high-efficiency demineralization from sugarcane straw.

Ultrasound assisted supramolecular liquid phase microextraction procedure for Sudan I at trace level in environmental samples.

A method based on supramolecular liquid phase microextraction has been developed for the preconcentration and determination of trace levels of Sudan I. 1-decanol and tetrahydrofuran were used as supramolecular solvent components. Trace levels of Sudan I were extracted into the extraction solvent phase at pH = 4.0 Analytical parameters such as pH value, supramolecular solvent volume, ultrasonication, centrifugation, model solution volume, matrix effects have been optimized. The limit of detection and the limit of quantification values for Sudan I were calculated as 1.74 μg L−1 and 5.75 μg L−1, respectively. In order to determine the accuracy of the method, addition and recovery studies were carried out to environmental samples.

Greener Is Better: First Approach for the Use of Natural Deep Eutectic Solvents (NADES) to Extract Antioxidants from the Medicinal Halophyte Polygonum maritimum L.

In this study, natural deep eutectic solvents (NADES) formed by choline chloride (ChCl), sucrose, fructose, glucose, and xylose, were used to extract antioxidants from the halophyte Polygonum maritimum L. (sea knotgrass) and compared with conventional solvents (ethanol and acetone). NADES and conventional extracts were made by an ultrasound-assisted procedure and evaluated for in vitro antioxidant properties by the radical scavenging activity (RSA) on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC), and copper chelating activity (CCA). Samples were profiled by liquid chromatography (LC)-electrospray ionization (ESI)-QTOF-MS analysis. ChCl:fructose was more efficient in the DPPH assay, than the acetone extract. ChCl:sucrose and ChCl:fructose extracts had the highest ORAC when compared with the acetone extract. NADES extracts had higher CCA, than the acetone extract. The phenolic composition of the NADES extracts was less complex than the conventional extracts, but the proportions of major antioxidants, such as flavonols and flavan-3-ols, were similar in all the solvents. Myricitrin was the major flavonoid in all of the samples, while gallic acid was the main phenolic acid in the conventional extracts and present in a greater amount in ChCl:fructose. Results suggest that NADES containing ChCl and sucrose/fructose can replace conventional solvents, especially acetone, in the extraction of antioxidants from sea knotgrass.

Multiple response optimization of ultrasound-assisted procedure for multi-element determination in Brazilian wine samples by microwave-induced plasma optical emission spectrometry

In the present work, a method was developed, optimized, and validated for the determination of aluminum, manganese, lead, copper, cadmium, and zinc by microwave-induced plasma optical emission spectrometry of wine samples from the São Francisco Valley, northeastern Brazil. The samples were subjected to a sonochemical treatment aiming at the degradation of the sample matrix. To optimize the analytical procedure, initially, a two-level fractional factorial design was used to study five experimental variables and determine which ones significantly affected the analytical response. In a second step, the significant variables were optimized using the Doehlert matrix as the response surface methodology and the desirability function as a strategy to optimize multiple responses. The optimum conditions established were concentrations of nitric acid (2.3 mol L−1) and hydrogen peroxide (9%). The developed method is simple, fast, and precise, has a low operational cost and low limits of detection and quantification. The accuracy confirmed by spike tests with recoveries ranging from 104 to 118% and comparative analysis of the results obtained using the proposed method and digestion total procedure. The method was applied for multi-element determination in three wine samples.

Benzopyrazine-Based Small Molecule Inhibitors As Trypanocidal and Leishmanicidal Agents: Green Synthesis, In Vitro, and In Silico Evaluations.

World Health Organization (WHO) identified twenty tropical disease categories as neglected tropical diseases (NTDs)1. Chagas’ disease (also known as American trypanosomiasis) and leishmaniasis are two major classes of NTDs. The total number of mortality, morbidity, and disability attributed each year due to these two categories of diseases in magnitudes is much higher than the so-called elite diseases like cancer, diabetes, AIDS, cardiovascular and neurodegenerative diseases. Impoverished communities around the world are the major victim of NTDs. The development of new and novel drugs in the battle against Chagas’ disease and leishmaniasis is highly anticipated. An easy and straightforward on-water green access to synthesize benzopyrazines is reported. This ultrasound-assisted procedure does not require any catalyst/support/additive/hazardous solvents and maintains a high atom economy. A series of eleven benzopyrazines has been synthesized, and most of the synthesized compounds possess the drug-likeness following Lipinski’s “Rule of 5”. Benzopyrazines 3 and 4 demonstrated moderate leishmanicidal activity against L. mexicana (M378) strain. The selective lead compound 1 showed good leishmanicidal, and trypanocidal activities (in vitro) against both L. mexicana (M378) and T. cruzi (NINOA) strains compared to the standard controls. The in vitro trypanocidal and leishmanicidal activities of the lead compound 1 have been validated by molecular docking studies against four biomolecular drug targets viz. T. cruzi histidyl-tRNA synthetase, T. cruzi trans-sialidase, leishmanial rRNA A-site, and leishmania major N-myristoyl transferase.

A Fast and Efficient Ultrasound-Assisted Extraction of Tocopherols in Cow Milk Followed by HPLC Determination.

A fast HPLC method with fluorescence detector (FD) was developed for the determination of three tocopherols (TOCs) in milk samples from Modicana cattle breed. The ultrasound-assisted procedure was optimized for the extraction of TOCs prior to HPLC/FD analysis, reducing sample preparation time and allowing a fast quantification of α-tocopherol, δ-tocopherol and γ tocopherol. The optimized ultrasonic extraction combines an efficient and simple saponification at room temperature and a rapid HPLC quantification of TOCs in milk. The precision of the full analytical procedure was satisfactory and the recoveries at three spiked levels were between 95.3% and 87.8%. The linear correlations were evaluated (R2 > 0.99) and the relative standard deviation (RSD) values for intra-day and inter-day tests at three spiked levels were below 1% for the retention time and below 5.20% for the area at low level spiking. The proposed procedure, reducing the experimental complexity, allowed accurate extraction and detection of three TOCs in milk samples from Modicana cattle breed.

Caco-2 in vitro model of human gastrointestinal tract for studying the absorption of titanium dioxide and silver nanoparticles from seafood

Titanium dioxide nanoparticles (TiO2 NPs) are widely used in industry as a white pigment (paints, paper industry and toothpastes), photocatalysts (environmental decontamination and photovoltaic cells), inorganic UV filter (sunscreens and personal care products) and as a food additive (E171) and antimicrobial food packaging material. Silver nanoparticles (Ag NPs) are used in photonics, microelectronics, catalysis and medicine due to their catalytic activity, magnetic and optical polarizability, electrical and thermal conductivities and enhanced Raman scattering. They also have antibacterial, antifungal and antiviral activities, as well as anti-inflammatory potential. The huge increase in the use of nano-based products, mainly metallic NPs, implies the presence of nanomaterials in the environment, and hence, the unintentional human ingestion through water or foods (gastrointestinal tract is the main pathway of NPs intake in humans).The presence of TiO2 NPs and Ag NPs in seafood samples was firstly established using an ultrasound assisted enzymatic hydrolysis procedure and sp-ICP-MS analysis. Several clams, cockles, mussels, razor clams, oysters and variegated scallops, which contain TiO2 NPs and Ag NPs, were subjected to an in vitro digestion process simulating human gastrointestinal digestion in the stomach and in the small and large intestine to determine the bioaccessibility of these NPs. Caco-2 cells were selected as model of human intestinal epithelium for transport studies because of the development of membrane transporters that are responsible for the uptake of chemicals. Parameters as transepithelial electrical resistance (TEER) and permeability of Lucifer Yellow were studied for establishing cell monolayer integrity. TiO2 NPs and Ag NPs transport as well as total Ti and Ag concentrations passing through the gastrointestinal epithelial barrier model (0–2 h) were assessed by sp-ICP-MS and ICP-MS in several molluscs.

Ultrasound-Assisted Synthesis, Antioxidant Activity and Computational Study of 1,3,4-Oxadiazol-2-amines

Development of synthetic procedures for the preparation of 1,3,4-oxadiazole derivatives has always been in the interest of researchers as a result of their widespread biological activities. In this study, an ultrasound-assisted procedure was proposed for the synthesis of 1,3,4-oxadiazol-2-amines form the reaction of hydrazides and cyanogen bromide. They were efficiently produced in 81-93% yields in the presence of ethanol and potassium bicarbonate as the reaction media and the base, respectively. Their antioxidant properties were determined via DPPH free radical scavenging method as one of the most basic steps in identifying other related biological effects. IC50 values were in the range of from 0.237 to 0.863 mM. The synthesized 1,3,4-oxadiazoles are protective agents against oxidative stress, and can be used in the treatment of cancer, candidiasis, diabetes, neurodegenerative and inflammatory diseases. Furthermore, bond dissociation energies (BDEs) and electron densities based NCI (non-covalent interactions) were calculated using density-functional theory (DFT) to understand the observed reactivities. It was found that reversible dipole-dipole forces play a key role in most interactions.

Enhanced low-temperature activity of CO2 methanation over ceria-promoted Ni-Al2O3 nanocatalyst

The present article, the influence of promoters (Zr, Ce, La, and Mo) on the structural properties and low temperature activity features of Ni-Al2O3 catalyst has been addressed in CO2 methanation reaction. The catalysts were made ready by the ultrasound assisted co-precipitated procedure and their features were described through XRD, H2-TPR, BET, SEM, CO2-TPD, TGA/DTA, and TPO techniques. The H2-TPR analysis showed the addition of promoters leading to the stronger interaction between nickel species and alumina, resulting in the formation of smaller crystallite size. Among the promoters, ceria can positively affect the catalytic performance of Ni-Al2O3 catalyst in CO2 methanation. The characterization results revealed that adding ceria favored the dispersion of NiO species, reduced Ni particle size, and increased the metal-support interaction. The 25wt.%Ni-5wt.%CeO2-Al2O3 catalyst possessed the superior catalytic activity and stability that attained the maximum CO2 conversion of 76.4% and CH4 selectivity of 99.1% at 350 °C.

New method for rapid identification and quantification of fungal biomass using ergosterol autofluorescence

This research reports on the development of a method to identify and quantify fungal biomass based on ergosterol autofluorescence using excitation-emission matrix (EEM) measurements. In the first stage of this work, several ergosterol extraction methods were evaluated by APCI-MS, where the ultrasound-assisted procedure showed the best results. Following an experimental design, various quantities of the dried mycelium of the fungus Schizophyllum commune were mixed with the starchy solid residue (BBR) from the babassu (Orbignya sp.) oil industry, and these samples were subjected to several ergosterol extraction methods. The EEM spectral data of the samples were subjected to Principal Component Analysis (PCA), which showed the possibility to qualitatively evaluate the presence of ergosterol in the samples by ergosterol autofluorescence without the addition of any reagent. In order to assess the feasibility of quantifying fungal biomass using ergosterol autofluorescence, the EEM spectral data and known amounts of fungal biomass were modeled using partial least squares (PLS) regression and a procedure of backward selection of predictors (AutoPLS) was applied to select the Excitation–Emission wavelength pairs that provide the lowest prediction error. The results revealed that the amount of fungal biomass in samples containing interfering substances (BBR) can be accurately predicted with R2CV = 0.939, R2P = 0.936, RPDcv = 4.07, RPDp = 4.06, RMSECV = 0.0731 and RMSEP = 0.0797. In order to obtain an easy-to-understand equation that expresses the relationship between fungal biomass and fluorescence intensity, multiple linear regression (MLR) was applied to the VIP variables selected by the AutoPLS method. The MLR model selected only 2 variables and showed a very good performance, with R2CV = 0.862, R2P = 0.809, RPDcv = 2.18, RPDp = 2.35, RMSECV = 0.137 and RMSEP = 0.138. This study demonstrated that ergosterol autofluorescence can be successfully used to quantify fungal biomass even when mixed with agroindustrial residues, in this case BBR.

Small-Scale Ultrasound-Assisted Extraction of Phenolics from Pomegranate Peels and Their Application as a Natural Reagent for the Colorimetric Assay of Iron

An environmentally friendly field-portable approach based on small-scale ultrasound-assisted extraction and micro-volume colorimetry was proposed for the determination of iron using natural reagent extracts from pomegranate peels. Ultrasound technology was utilized for the extraction of pomegranate peels in acetate buffer pH 5.5. Sonication parameters influencing the extraction process of natural reagents from pomegranate peel were investigated, including the type of solvent, mass/volume ratio of solvent, sonication time, temperature, and power. The efficiency of the ultrasound-assisted procedure for the extraction of iron from pharmaceutical formulations was evaluated by comparing to their label value and the reference method for pharmaceutical formulations. A linear calibration graph ranging from 1.0 to 10.0 mg L−1 Fe(III) was obtained from micro-volume colorimetric determination (at 530 nm) with limits of detection and quantification of 0.31 and 0.78 mg L−1, respectively. The reproducibility for 3.0 mg L−1 Fe(III) was 3.8% as the relative standard deviation. This developed system was successfully applied to determine the iron content in pharmaceutical formulations and the results agreed well with those obtained by a reference method. Good recoveries between 97 and 105% were obtained.

Ultrasound-assisted Endoscopic Evacuation of Recurrent Calf Hematoma Following Anterior Cruciate Ligament Reconstruction. Case Study

Hematoma of the calf is a rare complication following anterior cruciate ligament reconstruction (ACLR). The golden standard method of its treatment is puncture and aspiration. More advanced procedures are needed in difficult cases, such as prolonged he-ma-tomas. Among the novel management choices is endoscopy with ultrasound guidance. The aim of the study was to present the management of a post-surgical hematoma of the calf using endoscopic and ultrasound-assisted surgery. A 48-year-old patient un-der-went arthroscopic ACLR grafted with hamstrings tendons (semitendinosus and gracilis). Due to a hematoma developing at the donor site, he experienced edema and paresthesiae of the calf and foot that enhanced over time. An open reoperation failed and symptoms recurred. A second reoperation was performed as an endoscopic and ultrasound-assisted mini-invasive procedure. Re-sults were assessed postoperatively using the IKDC 2000 and Lysholm questionnaires. An evident increase in IKDC 2000 Score (from 14.9 points after open surgery to 77.0 one week after endoscopic treatment) and Lysholm Scale (26 points after first surgery and 84 one week after endoscopic surgery) was observed after the mini-invasive procedure. Edema and paresthesiae of the affect-ed limb completely disappeared four weeks after endoscopy. No complications of the novel procedure were found. Accordingly, en-doscopic and ultrasound-assisted evacuation of a prolonged calf hematoma appears an effective minimally-invasive and tar-geted procedure.

Effective coupling of BiPO4/g-C3N4 hybrid composites in ciprofloxacin photodegradation

A BiPO4/g-C3N4 photoactive system has been prepared by means of a practical ultrasound-assisted procedure in aqueous medium. The obtained hybrid composites were widely characterized by X-ray powder diffraction, Fourier-transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, scanning electron microscopy and N2 adsorption–desorption measurements. The photocatalytic features of the samples were examined through the degradation of orange G dye and ciprofloxacin antibiotic, where the higher photocatalytic performance for the degradation of both pollutants was achieved for the g-C3N4 with 1 wt% loading of BiPO4 (1-BiPO4 sample). To explain this outstanding performance, a possible mechanism involving the delocalization of the photogenerated charge carriers in the BiPO4/g-C3N4 system is discussed. Also, total organic carbon analysis and photocatalytic tests with radical scavengers were performed to elucidate the importance of the reactive oxidizing species during the photocatalytic process.

Environmentally friendly ultrasound-assisted synthesis of magnetic zeolitic imidazolate framework - Graphene oxide nanocomposites and pollutant removal from water

Ultrasound-assisted procedure is widely used for synthesizing materials due to its low cost, environmental friendly, facile, and mild properties. Herein, ultrasound-assisted synthesis of magnetic zeolitic imidazolate framework-8 (ZIF-8)/cobalt ferrite (CoFe2O4)/graphene oxide (GO) nanocomposites (ZIF-8/CoFe2O4/GO: ZCG) with different amounts of CoFe2O4/GO (25 and 50 mg denoted as ZCG-25, and ZCG-50) were studied in details. The GO was prepared from graphite. The synthesized materials including GO, ZIF-8, CoFe2O4, CoFe2O4/GO, ZCG-25, and ZCG-50 were fully characterized using BET, TEM, XRD, SEM, FTIR, and VSM. The ultrasound-assisted pollutant removal ability of the synthesized materials was investigated using Malachite Green (MG) as a model contaminant. The surface area of GO, CoFe2O4, ZCG-25, and ZCG-50 was 46, 52, 1543, and 2490 m2/g, respectively. Pollutant removal obeyed the pseudo-second order and Langmuir models. The pollutant removal capacity of ZCG-50, ZCG-25, CoFe2O4/GO, ZIF-8, CoFe2O4 and GO was 2610, 1948, 212, 901, 100, and 118 mg/g, respectively.

Optimization of ultrasound-assisted extraction of total phenolic contents and antioxidant activity using response surface methodology from jujube leaves (Ziziphus jujuba) and evaluation of anticholinesterase inhibitory activity

An ultrasound-assisted procedure for the extraction of phenolics (TPC) and antioxidant activity (AA) from jujube leaves have been investigated using response surface methodology (RSM). The Box–Behnken design was used to investigate the effects of three independent variables, solvent concentration (methanol/water; 40–100%), ultrasound-intensity (20–100%), and extraction time (3–15 min) on the responses. The optimal extraction conditions were 64.20% methanol, 73.60% ultrasound intensity, and 13.27 min. Under optimal conditions, the corresponding experimental values for TPC and AA were 6098.14 mg GAE/100 g DM and 4010.63 mg AAE/100 g DM. The experimental values were in close agreement with those predicted values within a 99% confidence level, thus indicating the suitability of the model and the success of RSM in optimizing the ultrasound assisted extraction of TPC and AA of jujube leaves. The results showed that optimized jujube leaves extract exhibited inhibitory effects on both acetylcholinesterase and butyrylcholinesterase with IC50 of 62.30 ± 2.54 and 147.00 ± 2.31 µg/mL, respectively.

Fast ultrasound-assisted synthesis of highly crystalline MIL-88A particles and their application as ethylene adsorbents

Highly crystalline MIL-88A particles have been successfully synthesized via fast ultrasound-assisted processes. The influence of the sonication generator and synthesis time on the structure, crystallinity, morphology and surface area of the materials were studied in detail. Under this modified ultrasonic method, X-ray diffraction patterns of MIL-88A particles showed highly crystalline structures in contrast to those reported in literature. Significant differences on surface areas and microporosity were appreciated under ultrasound conditions employed. Specific surface areas in the range between 179 and 359 m2 g−1 were obtained. That material synthesized under ultrasound batch conditions during 1 h had the highest surface area and microporous character. Different particle sizes and morphologies were obtained depending on the synthesis procedure. In general, probe sonicators led to smaller particle sizes. Moreover, a comparative study of the ethylene adsorption of the MIL-88A particles and several common MOFs in the ethylene adsorption was investigated. The results suggest that the modified ultrasound-assisted procedure for the synthesis of MIL-88A is effective to obtain highly crystalline particles, which are very efficient to adsorb ethylene molecules.

Ultrasound assisted enzymatic hydrolysis for isolating titanium dioxide nanoparticles from bivalve mollusk before sp-ICP-MS

Applicability of single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) using dwell times equal to or shorter than 100 μs has been tested for assessing titanium dioxide nanoparticles (TiO2 NPs) in bivalve mollusks. TiO2 NPs isolation from fresh mollusk tissues was achieved by ultrasound assisted enzymatic hydrolysis procedure using a pancreatin/lipase mixture. Optimum extraction conditions imply ultrasonication (60% amplitude) for 10 min, and 7.5 mL of a solution containing 3.0 g L−1of pancreatin and lipase (pH 7.4). The developed method was found to be repeatable (repeatability of 17% for the over-all procedure, TiO2 NPs concentration of 5.33 × 107 ± 8.89 × 106, n = 11), showing a limit of detection of 5.28 × 106 NPs g−1, and a limit of detection in size of 24.4–30.4 nm, based on the 3σ criteria, and on the 3σ/5 σ criteria, respectively. The analytical recovery within the 90–99% range (use of TiO2 NPs standards of 50 nm at 7 and 14 μg L−1 as Ti). Several bivalve mollusks (clams, cockles, mussels, razor clams, oysters and variegated scallops) were analyzed for total titanium (ICP-MS after microwave assisted acid digestion), and for TiO2 NPs by the proposed method. TiO2 NPs concentrations were within the 2.36 × 107-1.25 × 108 NPs g−1 range, and the most frequent sizes were from 50 to 70 nm.