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Analytical Methods for Toxics Determination

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Analytical Chemistry".

Deadline for manuscript submissions: closed (29 February 2020) | Viewed by 30984

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Prof. Dr. Clinio Locatelli

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Department of Chemistry “Giacomo Ciamician”, Alma Mater Studiorum University of Bologna, Via Selmi 2, I-40126 Bologna, Italy
Interests: analytical methods set up; environmental field; food contaminants; spectroscopy; voltammetry
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Dr. Marcello Locatelli

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Department of Pharmacy, University “G. d\'Annunzio” of Chieti and Pescara, Chieti, Italy
Interests: innovative (micro)extraction procedures; hyphenated instrument configurations; bioactive compounds; characterization; fingerprints; method validation; HPLC; mass spectrometry; biological matrices; chromatography; analytical chemistry; sample preparation; green analytical methodologies
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Prof. Dr. Dora Melucci

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Department of Chemistry “Giacomo Ciamician”, Alma Mater Studiorum University of Bologna, Via Selmi 2, I-40126 Bologna, Italy
Interests: chemometrics; environmental chemistry; forensics; food chemistry; pharmaceutics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent decades, but especially in recent years, the rapid spread of toxic species has occurred in all matrices. Evidently, these contaminants, both of inorganic and organic origin, are very dangerous pollutants for human health, owing to their bioaccumulation and toxicity. They come from almost all human activities, such as, for example, industries, agriculture, vehicular traffic, and urban heating.

Considering that often these species occur in the various real matrices at extremely low concentrations, the analytical methodologies must evidently show their possible application by verifying the correctness of all the steps: sampling, sample preparation, instrumental measurement, and statistical data processing.

Another extremely important aspect concerns the fact that the development of new analytical methodologies, and the contemporary lack or inadequacy of regulations regarding the determination of toxic species in the most varied matrices, can obviously give to the legislator the possibility to update and improve the above-mentioned regulations.

This Special Issue aims to attract contributions on all aspects linked to the different analytical methods used for the determination of toxic species in the most varied matrices—food, environmental, forensic, biological, and so on—focusing particularly on the fundamental parameters of interest to set-up an analytical procedure, such as precision and trueness (that together give accuracy); the limits of detection and quantification; selectivity; and, especially, sensitivity.

Prof. Dr. Clinio Locatelli
Prof. Marcello Locatelli
Prof. Dora Melucci
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Inorganic toxic species
Organic toxic species
Analytical methods
Chemometrics
Practical applications.

Published Papers (10 papers)

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Research

12 pages, 2544 KiB

Open AccessArticle

Analysis of Pollution in High Voltage Insulators via Laser-Induced Breakdown Spectroscopy

by Xinwei Wang, Shan Lu, Tianzheng Wang, Xinran Qin, Xilin Wang and Zhidong Jia

Molecules 2020, 25(4), 822; https://doi.org/10.3390/molecules25040822 - 13 Feb 2020

Cited by 12 | Viewed by 2503

Abstract

Surface pollution deposition in a high voltage surface can reduce the surface flashover voltage, which is considered to be a serious accident in the transmission of electric power for the high conductivity of pollution in wet weather, such as rain or fog. Accordingly, a rapid and accurate online pollution detection method is of great importance for monitoring the safe status of transmission lines. Usually, to detect the equivalent salt deposit density (ESDD) and non-soluble deposit density (NSDD), the pollution should be collected when power cut off and bring back to lab, time-consuming, low accuracy and unable to meet the online detection. Laser-induced breakdown spectroscopy (LIBS) shows the highest potential for achieving online pollution detection, but its application in high voltage electrical engineering has only just begun to be examined. In this study, a LIBS method for quantitatively detecting the compositions of pollutions on the insulators was investigated, and the spectral characteristics of a natural pollution sample were examined. The energy spectra and LIBS analysis results were compared. LIBS was shown to detect pollution elements that were not detected by conventional energy spectroscopy and had an improved capacity to determine pollution composition. Furthermore, the effects of parameters, such as laser energy intensity and delay time, were investigated for artificial pollutions. Increasing the laser energy intensity and selecting a suitable delay time could enhance the precision and relative spectral intensities of the elements. Additionally, reducing the particle size and increasing the density achieved the same results. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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28 pages, 870 KiB

Open AccessFeature PaperArticle

Assessment of the Quality of Polluted Areas in Northwest Romania Based on the Content of Elements in Different Organs of Grapevine (Vitis vinifera L.)

by Florin Dumitru Bora, Claudiu Ioan Bunea, Romeo Chira and Andrea Bunea

Molecules 2020, 25(3), 750; https://doi.org/10.3390/molecules25030750 - 09 Feb 2020

Cited by 18 | Viewed by 2916

Abstract

The purpose of this study was to evaluate the environmental quality of polluted areas near the Baia Mare Mining and Smelting Complex for future improvements the quality of the environment in polluted areas, such as the city of Baia Mare and its surroundings. Samples of soil and organs of grapevine (Vitis vinifera L.) were collected from Baia Mare, Baia Sprie and surrounding areas (Simleul Silvaniei) and their content of Cu, Zn, Pb, Cd, Ni, Co, As, Cr, Hg were analyzed. Most soil and plant samples showed higher metal concentrations in Baia Mare and Baia Sprie areas compared to Simleul Silvaniei, exceeding the normal values. The results obtained from the translocation factors, mobility ratio, as well as from Pearson correlation study confirmed that very useful information is recorded in plant organs: root, canes, leaves and fruit. Results also indicated that Vitis vinifera L. has some highly effective strategies to tolerate heavy metal-induced stress, may also be useful as a vegetation protection barrier from considerable atmospheric pollution. At the same time, berries are safe for consumption to a large degree, which is a great advantage of this species. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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13 pages, 660 KiB

Open AccessArticle

Development of a Direct Competitive ELISA Kit for Detecting Deoxynivalenol Contamination in Wheat

by Li Han, Yue-Tao Li, Jin-Qing Jiang, Ren-Feng Li, Guo-Ying Fan, Jun-Mei Lv, Ye Zhou, Wen-Ju Zhang and Zi-Liang Wang

Molecules 2020, 25(1), 50; https://doi.org/10.3390/molecules25010050 - 22 Dec 2019

Cited by 17 | Viewed by 3264

Abstract

This study was conducted to develop a self-assembled direct competitive enzyme-linked immunosorbent assay (dcELISA) kit for the detection of deoxynivalenol (DON) in food and feed grains. Based on the preparation of anti-DON monoclonal antibodies, we established a standard curve with dcELISA and optimized the detection conditions. The performance of the kit was evaluated by comparison with high-performance liquid chromatography (HPLC). The minimum detection limit of DON with the kit was 0.62 ng/mL, the linear range was from 1.0 to 113.24 ng/mL and the half-maximal inhibition concentration (IC₅₀) was 6.61 ng/mL in the working buffer; there was a limit of detection (LOD) of 62 ng/g, and the detection range was from 100 to 11324 ng/g in authentic agricultural samples. We examined four samples of wheat bran, wheat flour, corn flour and corn for DON recovery. The average recovery was in the range of 77.1% to 107.0%, and the relative standard deviation (RSD) ranged from 4.2% to 11.9%. In addition, the kit has the advantages of high specificity, good stability, a long effective life and negligible sample matrix interference. Finally, wheat samples from farms in the six provinces of Henan, Anhui, Hebei, Shandong, Jiangsu and Gansu in China were analyzed by the kit. A total of 30 samples were randomly checked (five samples in each province), and the results were in good agreement with the standardized HPLC method. These tests showed that the dcELISA kit had good performance and met relevant technical requirements, and it had the characteristics of accuracy, reliability, convenience and high-throughput screening for DON detection. Therefore, the developed kit is suitable for rapid screening of DON in marketed products. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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11 pages, 1857 KiB

Open AccessArticle

Application of Composite NanoMaterial to Determine Phenols in Wastewater by Solid Phase Micro Membrane Tip Extraction and Capillary Electrophoresis

by Nora Hamad Al-Shaalan, Imran Ali, Zeid A. ALOthman, Lamya Hamad Al-Wahaibi and Hadeel Alabdulmonem

Molecules 2019, 24(19), 3443; https://doi.org/10.3390/molecules24193443 - 23 Sep 2019

Cited by 10 | Viewed by 2691

Abstract

Composite nanoparticles were used in solid phase micro membrane tip extraction and capillary electrophoresis to determine phenol and p-amino-phenol in wastewater. The optimized conditions were 100 g/L concentration, 40 min contact time, 11 pH, 5 mg/mL nanoparticles amounts, 60 min desorption time, 9 desorption pH and 298 K temperature. Capillary electrophoresis conditions were phosphate buffer (15 mM, pH 7.0) background electrolyte, 18 kV applied voltage, 214 nm UV detection, 30 s sample loading at 23 ± 1 °C. The maximum percent uptakes of p-amino-phenol and phenol were 80.0 and 85.0%. High ratio recoveries of p-amino-phenol and phenol from nanomaterial were 99.0 and 98. Consequently, the actual extractions of p-amino-phenol and phenol from wastewater were 79.2 and 83.30 percent. The migration times of phenol and p-amino-phenol and were 9.0 and 12.0 min. The detection limits of phenol and p-amino-phenols were 0.1 and 0.2 µg/L after extraction and CE. Therefore, this combination of solid phase micro membrane tip extraction and capillary electrophoresis may be considered as the ideal one for monitoring of toxic phenol and p-amino-phenol in water sample. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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15 pages, 2728 KiB

Open AccessArticle

Novel MIPs-Parabens based SPE Stationary Phases Characterization and Application

by Angela Tartaglia, Abuzar Kabir, Songul Ulusoy, Halil Ibrahim Ulusoy, Giuseppe Maria Merone, Fabio Savini, Cristian D’Ovidio, Ugo de Grazia, Serena Gabrielli, Fabio Maroni, Pantaleone Bruni, Fausto Croce, Dora Melucci, Kenneth G. Furton and Marcello Locatelli

Molecules 2019, 24(18), 3334; https://doi.org/10.3390/molecules24183334 - 13 Sep 2019

Cited by 17 | Viewed by 3326

Abstract

In this work, the synthesis, characterization, and application of novel parabens imprinted polymers as highly selective solid-phase extraction (SPE) sorbents have been reported. The imprinted polymers were created using sol–gel molecular imprinting process. All the seven parabens were considered herein in order to check the phase selectivity. By means of a validated HPLC-photodiode array detector (PDA) method all seven parabens were resolved in a single chromatographic run of 25 min. These SPE sorbents, in-house packed in SPE empty cartridges, were first characterized in terms of extraction capability, breakthrough volume, retention volume, hold-up volume, number of theoretical plates, and retention factor. Finally, the device was applied to a real urine sample to check the method feasibility on a very complex matrix. The new paraben imprinted SPE sorbents, not yet present in the literature, potentially encourage the development of novel molecularly imprinted polymers (MIPs) to enhance the extraction efficiency, and consequently the overall analytical performances, when the trace quantification is required. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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18 pages, 3289 KiB

Open AccessArticle

Heavy Metals Bioindication Potential of the Common Weeds Senecio vulgaris L., Polygonum aviculare L. and Poa annua L.

by Mirko Salinitro, Annalisa Tassoni, Sonia Casolari, Francesco de Laurentiis, Alessandro Zappi and Dora Melucci

Molecules 2019, 24(15), 2813; https://doi.org/10.3390/molecules24152813 - 01 Aug 2019

Cited by 12 | Viewed by 2987

Abstract

In recent years, heavy metals (HMs) levels in soil and vegetation have increased considerably due to traffic pollution. These pollutants can be taken up from the soil through the root system. The ability of plants to accumulate HMs into their tissues can therefore be used to monitor soil pollution. The aim of this study was to test the ruderal species Senecio vulgaris L., Polygonum aviculare L., and Poa annua L., as possible candidates for biomonitoring Cu, Zn, Cd, Cr, Ni and Pb in multiple environments. The soils analyzed in this work came from three different environments (urban, woodland, and ultramafic), and therefore deeply differed for their metal content, texture, pH, and organic matter (OM) content. All urban soils were characterized by high OM content and presence of anthropogenic metals like Pb, Zn, Cd, and Cu. Woodland soils were sandy and characterized by low metal content and low OM content, and ultramafic soils had high Ni and Cr content. This soil variability affected the bioindication properties of the three studied species, leading to the exclusion of most metals (Zn, Cu, Cr, Cd, and Pb) and one species (P. aviculare) due to the lack of linear relations between metal in soil and metal in plants. Senecio vulgaris and Poa annua, conversely, appeared to be good indicators of Ni in all the soils tested. A high linear correlation between total Ni in soil and Ni concentration in P. annua shoots (R² = 0.78) was found and similar results were achieved for S. vulgaris (R² = 0.88). Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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10 pages, 825 KiB

Open AccessArticle

Analysis of the Overlapped Electrochemical Signals of Hydrochlorothiazide and Pyridoxine on the Ethylenediamine-Modified Glassy Carbon Electrode by Use of Chemometrics Methods

by Yue Zhang, Yan Zhou, Shujun Chen, Yashi You, Ping Qiu and Yongnian Ni

Molecules 2019, 24(14), 2536; https://doi.org/10.3390/molecules24142536 - 11 Jul 2019

Cited by 2 | Viewed by 2440

Abstract

In this work, the electrochemical behavior of hydrochlorothiazide and pyridoxine on the ethylenediamine-modified glassy carbon electrode were investigated by differential pulse voltammetry. In pH 3.4 Britton-Robinson (B-R) buffer solution, both hydrochlorothiazide and pyridoxine had a pair of sensitive irreversible oxidation peaks, that overlapped in the 1.10 V to 1.20 V potential range. Under the optimum experimental conditions, the peak current was linearly related to hydrochlorothiazide and pyridoxine in the concentration range of 0.10–2.0 μg/mL and 0.02–0.40 μg/mL, respectively. Chemometrics methods, including classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS), were introduced to resolve the overlapped signals and determine the two components in mixtures, which avoided the troublesome steps of separation and purification. Finally, the simultaneous determination of the two components in commercial pharmaceuticals was performed with satisfactory results. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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15 pages, 2613 KiB

Open AccessArticle

Development of a Method for the Quantification of Clotrimazole and Itraconazole and Study of Their Stability in a New Microemulsion for the Treatment of Sporotrichosis

by Patricia Garcia Ferreira, Carolina Guimarães de Souza Lima, Letícia Lorena Noronha, Marcela Cristina de Moraes, Fernando de Carvalho da Silva, Alessandra Lifsitch Viçosa, Débora Omena Futuro and Vitor Francisco Ferreira

Molecules 2019, 24(12), 2333; https://doi.org/10.3390/molecules24122333 - 25 Jun 2019

Cited by 13 | Viewed by 4403

Abstract

Sporotrichosis occurs worldwide and is caused by the fungus Sporothrix brasiliensis. This agent has a high zoonotic potential and is transmitted mainly by bites and scratches from infected felines. A new association between the drugs clotrimazole and itraconazole is shown to be effective against S. brasiliensis yeasts. This association was formulated as a microemulsion containing benzyl alcohol as oil, Tween^® 60 and propylene glycol as surfactant and cosurfactant, respectively, and water. Initially, the compatibility between clotrimazole and itraconazole was studied using differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (PXRD). Additionally, a simple and efficient analytical HPLC method was developed to simultaneously determine the concentration of clotrimazole and itraconazole in the novel microemulsion. The developed method proved to be efficient, robust, and reproducible for both components of the microemulsion. We also performed an accelerated stability study of this formulation, and the developed analytical method was applied to monitor the content of active ingredients. Interestingly, these investigations led to the detection of a known clotrimazole degradation product whose structure was confirmed using NMR and HRMS, as well as a possible interaction between itraconazole and benzyl alcohol. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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12 pages, 1489 KiB

Open AccessArticle

Enhancement of Solasodine Extracted from Fruits of Solanum nigrum L. by Microwave-Assisted Aqueous Two-Phase Extraction and Analysis by High-Performance Liquid Chromatography

by Li Lin, Wen Yang, Xing Wei, Yi Wang, Li Zhang, Yunsong Zhang, Zhiming Zhang, Ying Zhao and Maojun Zhao

Molecules 2019, 24(12), 2294; https://doi.org/10.3390/molecules24122294 - 21 Jun 2019

Cited by 7 | Viewed by 2930

Abstract

Background: Solasodine is a major bioactive ingredient in Solanum nigrum L. that has strong pharmacological characteristics. Therefore, the development of a simple and effective extraction method for obtaining solasodine is highly important. This study aims to provide a rapid and effective method for extracting solasodine from Solanum nigrum L. by microwave-assisted aqueous two-phase extraction (MAATPE). Methods: First, the high-performance liquid chromatography (HPLC) conditions were established for the detection of solasodine. Then, the aqueous two-phase system (ATPS) compositions were examined. On the basis of the results of single-factor experiments, for a better yield, response surface methodology (RSM) was used to optimize influential factors including the extraction temperature, extraction time and liquid-to-solid ratio. Results: The maximum extraction yield of 7.11 ± 0.08 mg/g was obtained at 44 °C, an extraction time of 15 min, and a liquid-to-solid ratio of 42:1 mL/g in the ATPS consisting of EtOH solvent, (NH₄)₂SO₄, and water (28:16:56, w/w/w). The extraction yield of the alkaloid obtained using this method was markedly higher than those of microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE). Conclusions: In this work, solasodine was extracted by MAATPE for the first time and a high yield was obtained. MAATPE is a simple, rapid, and green technique for extraction from medical plants. Thus, the present study will enable the development of a feasible extraction method of active alkaloids from Solanum nigrum L. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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12 pages, 1403 KiB

Open AccessArticle

Screen-printed Microsensors Using Polyoctyl-thiophene (POT) Conducting Polymer As Solid Transducer for Ultratrace Determination of Azides

by Ahmed Galal Eldin, Abd El-Galil E. Amr, Ayman H. Kamel and Saad S. M. Hassan

Molecules 2019, 24(7), 1392; https://doi.org/10.3390/molecules24071392 - 09 Apr 2019

Cited by 17 | Viewed by 2688

Abstract

Two novel all-solid-state potentiometric sensors for the determination of azide ion are prepared and described here for the first time. The sensors are based on the use of iron II-phthalocyanine (Fe-PC) neutral carrier complex and nitron-azide ion-pair complex (Nit-N₃⁻) as active recognition selective receptors, tetradodecylammonium tetrakis(4-chlorophenyl) borate (ETH 500) as lipophilic cationic additives and poly(octylthiophene) (POT) as the solid contact material on carbon screen-printed devices made from a ceramic substrate. The solid-contact material (POT) is placed on a carbon substrate (2 mm diameter) by drop-casting, followed, after drying, by coating with a plasticized PVC membrane containing the recognition sensing complexes. Over the pH range 6-9, the sensors display fast (< 10 s), linear potentiometric response for 1.0 × 10⁻²–1.0 × 10⁻⁷ M azide with low detection limit of 1.0 × 10⁻⁷ and 7.7 × 10⁻⁸ M (i.e., 6.2–4.8 ng/ml) for Fe-PC/POT/and Nit-N₃⁻/POT based sensors, respectively. The high potential stability and sensitivity of the proposed sensors are confirmed by electrochemical impedance spectroscopy (EIS) and constant-current chronopotentiometry measurement techniques. Strong membrane adhesion and absence of delamination of the membrane, due to possible formation of a water film between the recognition membranes and the electron conductor are also verified. The proposed sensors are successfully applied for azide quantification in synthetic primer mixture samples. Advantages offered by these sensors are the robustness, ease of fabrication, simple operation, stable potential response, high selectivity, good sensitivity and low cost. Full article

(This article belongs to the Special Issue Analytical Methods for Toxics Determination)

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