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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 (30 September 2023) | Viewed by 19796

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Dr. Petr Bednar

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Dept Analyt Chem, Reg Ctr Adv Technol & Mat, Fac Sci, Palacky Univ, 17 Listopadu 12, 77146 Olomouc, Czech Republic
Interests: analytical chemistry; liquid chromatography; hyphenation of separation techniques (LC, CE) with mass spectrometry; natural compounds analysis; study of metabolism; analysis of archaeological samples; chiral separation; desorption/ionization mass spectrometry; ion mobility mass spectrometry; study of equilibrium reactions using retention and migration data

Special Issue Information

Dear Colleagues,

Analytical Chemistry as scientific field is a good example of the connection of fundamental research in chemical, physical and biological branches to demands of practice. Mutual stimulation of fundamental and applied research makes Analytical Chemistry a dynamically developing area. The current high level of mechanical engineering and microelectronics accelerates the advancement of instrumental analytical techniques. Approaches to analytical data processing are being improved under the dictation of their increasing volume and with the possibilities of explosively developing informatics. Optimization and validation of analytical procedures are sped-up and automated. However, sophisticated instrumentation, although supported by Artificial Intelligence, is not self-saving. Experiences and thorough knowledge of possibilities and risks throughout the whole analytical procedure from the design of the experiment, to the sampling, sample treatment, and analysis and data processing remain essential for successful research. The integration of the entire analytical process and its transfer into practice is the subject of Applied Analytical Chemistry.

This Special Issue aims to cover recent progress and trends in Applied Analytical Chemistry. Papers focused on novel sampling and sample treatment procedures, the utilization of up-to-date techniques and methods in analytical practice are welcome. Moreover, progressive approaches in design of experiment and data processing proven in real situations fit within the focus of this Special Issue. Emphasis should be placed on the integrity of the whole analytical process. This Special Issue is open to all types of analytical techniques and their (synergistic) combinations applied especially but not only in the following areas:

food production
forensic practice and archaeology
environmental monitoring
clinical practice
quality control in industry

Dr. Petr Bednar
Guest Editor

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Research

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10 pages, 670 KiB

Open AccessArticle

Simultaneous Measurement and Distribution Analysis of Urinary Nicotine, Cotinine, Trans-3′-Hydroxycotinine, Nornicotine, Anabasine, and Total Nicotine Equivalents in a Large Korean Population

by Hyun-Seung Lee, Mi-Ryung Chun and Soo-Youn Lee

Molecules 2023, 28(23), 7685; https://doi.org/10.3390/molecules28237685 - 21 Nov 2023

Viewed by 635

Abstract

Measurement of multiple nicotine metabolites and total nicotine equivalents (TNE) might be a more reliable strategy for tobacco exposure verification than measuring single urinary cotinine alone. We simultaneously measured nicotine, cotinine, 3-OH cotinine, nornicotine, and anabasine using 19,874 urine samples collected from the Korean National Health and Nutrition Examination Survey. Of all samples, 18.6% were positive for cotinine, 17.4% for nicotine, 17.3% for nornicotine, 17.6% for 3-OH cotinine, and 13.2% for anabasine. Of the cotinine negative samples, less than 0.3% were positive for all nicotine metabolites, but not for anabasine (5.7%). The agreement of the classification of smoking status by cotinine combined with nicotine metabolites was 0.982–0.994 (Cohen’s kappa). TNE3 (the molar sum of urinary nicotine, cotinine, and 3-OH cotinine) was most strongly correlated with cotinine compared to the other nicotine metabolites; however, anabasine was less strongly correlated with other biomarkers. Among anabasine-positive samples, 30% were negative for nicotine or its metabolites, and 25% were undetectable. Our study shows that the single measurement of urinary cotinine is simple and has a comparable classification of smoking status to differentiate between current smokers and non-smokers relative to the measurement of multiple nicotine metabolites. However, measurement of multiple nicotine metabolites and TNE3 could be useful for monitoring exposure to low-level or secondhand smoke exposure and for determining individual differences in nicotine metabolism. Geometric or cultural factors should be considered for the differentiation of tobacco use from patients with nicotine replacement therapy by anabasine. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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18 pages, 2133 KiB

Open AccessArticle

Non-Targeted Spectranomics for the Early Detection of Xylella fastidiosa Infection in Asymptomatic Olive Trees, cv. Cellina di Nardò

by Elhussein Ahmed, Biagia Musio, Stefano Todisco, Piero Mastrorilli, Vito Gallo, Maria Saponari, Franco Nigro, Stefania Gualano and Franco Santoro

Molecules 2023, 28(22), 7512; https://doi.org/10.3390/molecules28227512 - 09 Nov 2023

Viewed by 1094

Abstract

Olive quick decline syndrome (OQDS) is a disease that has been seriously affecting olive trees in southern Italy since around 2009. During the disease, caused by Xylella fastidiosa subsp. pauca sequence type ST53 (Xf), the flow of water and nutrients within the trees is significantly compromised. Initially, infected trees may not show any symptoms, making early detection challenging. In this study, young artificially infected plants of the susceptible cultivar Cellina di Nardò were grown in a controlled environment and co-inoculated with additional xylem-inhabiting fungi. Asymptomatic leaves of olive plants at an early stage of infection were collected and analyzed using nuclear magnetic resonance (NMR), hyperspectral reflectance (HSR), and chemometrics. The application of a spectranomic approach contributed to shedding light on the relationship between the presence of specific hydrosoluble metabolites and the optical properties of both asymptomatic Xf-infected and non-infected olive leaves. Significant correlations between wavebands located in the range of 530–560 nm and 1380–1470 nm, and the following metabolites were found to be indicative of Xf infection: malic acid, fructose, sucrose, oleuropein derivatives, and formic acid. This information is the key to the development of HSR-based sensors capable of early detection of Xf infections in olive trees. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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21 pages, 2641 KiB

Open AccessArticle

Detection and Quantification of Bisphenol A in Surface Water Using Absorbance–Transmittance and Fluorescence Excitation–Emission Matrices (A-TEEM) Coupled with Multiway Techniques

by Thomas Ingwani, Nhamo Chaukura, Bhekie B. Mamba, Thabo T. I. Nkambule and Adam M. Gilmore

Molecules 2023, 28(20), 7048; https://doi.org/10.3390/molecules28207048 - 12 Oct 2023

Viewed by 1054

Abstract

In the present protocol, we determined the presence and concentrations of bisphenol A (BPA) spiked in surface water samples using EEM fluorescence spectroscopy in conjunction with modelling using partial least squares (PLS) and parallel factor (PARAFAC). PARAFAC modelling of the EEM fluorescence data obtained from surface water samples contaminated with BPA unraveled four fluorophores including BPA. The best outcomes were obtained for BPA concentration (R² = 0.996; standard deviation to prediction error’s root mean square ratio (RPD) = 3.41; and a Pearson’s r value of 0.998). With these values of R² and Pearson’s r, the PLS model showed a strong correlation between the predicted and measured BPA concentrations. The detection and quantification limits of the method were 3.512 and 11.708 micro molar (µM), respectively. In conclusion, BPA can be precisely detected and its concentration in surface water predicted using the PARAFAC and PLS models developed in this study and fluorescence EEM data collected from BPA-contaminated water. It is necessary to spatially relate surface water contamination data with other datasets in order to connect drinking water quality issues with health, environmental restoration, and environmental justice concerns. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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16 pages, 4636 KiB

Open AccessArticle

Protected Geographical Indication Discrimination of Zhejiang and Non-Zhejiang Ophiopogonis japonicus by Near-Infrared (NIR) Spectroscopy Combined with Chemometrics: The Influence of Different Stoichiometric and Spectrogram Pretreatment Methods

by Qingge Ji, Chaofeng Li, Xianshu Fu, Jinyan Liao, Xuezhen Hong, Xiaoping Yu, Zihong Ye, Mingzhou Zhang and Yulou Qiu

Molecules 2023, 28(6), 2803; https://doi.org/10.3390/molecules28062803 - 20 Mar 2023

Cited by 2 | Viewed by 1169

Abstract

This paper presents a method for the protected geographical indication discrimination of Ophiopogon japonicus from Zhejiang and elsewhere using near-infrared (NIR) spectroscopy combined with chemometrics. A total of 3657 Ophiopogon japonicus samples from five major production areas in China were analyzed by NIR spectroscopy, and divided into 2127 from Zhejiang and 1530 from other areas (‘non-Zhejiang’). Principal component analysis (PCA) was selected to screen outliers and eliminate them. Monte Carlo cross validation (MCCV) was introduced to divide the training set and test set according to a ratio of 3:7. The raw spectra were preprocessed by nine single and partial combination methods such as the standard normal variable (SNV) and derivative, and then modeled by partial least squares regression (PLSR), a support vector machine (SVM), and soft independent modeling of class analogies (SIMCA). The effects of different pretreatment and chemometrics methods on the model are discussed. The results showed that the three pattern recognition methods were effective in geographical origin tracing, and selecting the appropriate preprocessing method could improve the traceability accuracy. The accuracy of PLSR after the standard normal variable was better, with R² reaching 0.9979, while that of the second derivative was the lowest with an R² of 0.9656. After the SNV pretreatment, the accuracy of the training set and test set of SVM reached the highest values, which were 99.73% and 98.40%, respectively. The accuracy of SIMCA pretreated with SNV and MSC was the highest for the origin traceability of Ophiopogon japonicus, which could reach 100%. The distance between the two classification models of SIMCA-SNV and SIMCA-MSC is greater than 3, indicating that the SIMCA model has good performance. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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13 pages, 1468 KiB

Open AccessArticle

A New Method for the Determination of Total Content of Vitamin C, Ascorbic and Dehydroascorbic Acid, in Food Products with the Voltammetric Technique with the Use of Tris(2-carboxyethyl)phosphine as a Reducing Reagent

by Artur Mazurek and Marzena Włodarczyk-Stasiak

Molecules 2023, 28(2), 812; https://doi.org/10.3390/molecules28020812 - 13 Jan 2023

Cited by 5 | Viewed by 2364

Abstract

The objective of the study was to develop a new method for the determination of the total content of vitamin C and dehydroascorbic acid in food, based on the technique of differential pulse voltammetry with the use of a boron-doped diamond electrode modified with mercury film. A comparison was made between the results obtained with the developed method and a proposed reference method based on high-performance liquid chromatography with spectrophotometric detection. The reduction of dehydroascorbic acid was performed with the use of tris(2-carboxyethyl)phosphine. The interference caused by the presence of tris(2-carboxyethyl)phosphine during the voltammetric determination of ascorbic acid was effectively eliminated through a reaction with N-ethylmaleimide. The conducted validation of the voltammetric method indicated that correct results of analysis of the total content of vitamin C and ascorbic acid were obtained. Analysis of the content of dehydroascorbic acid was imprecise due to the application of the differential method. The results of the analyses and the determined validation parameters of the developed method are characterised by a high degree of conformance with the results obtained with the chromatographic reference method, which indicates the equivalence of the two methods. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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15 pages, 3838 KiB

Open AccessArticle

Rapid Determination of Geniposide and Baicalin in Lanqin Oral Solution by Near-Infrared Spectroscopy with Chemometric Algorithms during Alcohol Precipitation

by Hui Ma, Ming Chen, Siyu Zhang, Hongye Pan, Yong Chen and Yongjiang Wu

Molecules 2023, 28(1), 4; https://doi.org/10.3390/molecules28010004 - 20 Dec 2022

Cited by 1 | Viewed by 1163

Abstract

The selection of key variables is an important step that improves the prediction performance of a near-infrared (NIR) real-time monitoring system. Combined with chemometrics, NIR spectroscopy was employed to construct high predictive accuracy, interpretable models for the rapid detection of the alcohol precipitation process of Lanqin oral solution (LOS). The variable combination population analysis-iteratively retaining informative variables (VCPA-IRIV) was innovatively introduced into the variable screening process of the model of geniposide and baicalin. Compared with the commonly used synergy interval partial least squares regression, competitive adaptive reweighted sampling, and random frog, VCPA-IRIV achieved the maximum compression of variable space. VCPA-IRIV-partial least squares regression (PLSR) only needs to use about 1% of the number of variables of the original data set to construct models with Rp values greater than 0.95 and RMSEP values less than 10%. With the advantages of simplicity and strong interpretability, the prediction ability of the PLSR models had been significantly improved simultaneously. The VCPA-IRIV-PLSR models met the requirements of rapid quality detection. The real-time detection system can help researchers to understand the quality rules of geniposide and baicalin in the alcohol precipitation process of LOS and provide a reference for the optimization of a LOS quality control system. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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8 pages, 18253 KiB

Open AccessArticle

First Evidence of “Earth Wax” Inside the Casting Molds from the Roman Era

by Klára Jagošová, Jan Jílek, Pavel Fojtík, Ivan Čižmář, Miroslav Popelka, Ondřej Kurka and Lukáš Kučera

Molecules 2021, 26(14), 4259; https://doi.org/10.3390/molecules26144259 - 13 Jul 2021

Cited by 2 | Viewed by 2422

Abstract

This research was focused on the analysis of material composition and organic residues present in three molds found in the Moravian region (Czech Republic) belonging to the Roman era. X-ray fluorescence spectroscopy pointed out the possible remelting of Roman objects in Barbarian territory. The analysis of organic residues retrieved from the internal part of mold #2 by pyrolysis-gas chromatography/mass spectrometry proved the presence of ozokerite wax (“earth wax”). Consequent analysis of this organic residue by Atmospheric Solids Analysis Probe–ion mobility spectrometry–high-resolution mass spectrometry (ASAP-IMS-HRMS) confirmed the presence of ceresin, the main component of ozokerite. Ceresin was also detected in a sample of the organic residue from mold #1. Note that this is the first application of ASAP-IMS-HRMS in archaeological research. The remains of earth wax in molds suggest the production of wax models as an intermediate stage for the production of lost-wax ceramic casting molds. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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16 pages, 4280 KiB

Open AccessArticle

What about Dinner? Chemical and Microresidue Analysis Reveals the Function of Late Neolithic Ceramic Pans

by Jaromír Beneš, Valentina Todoroska, Kristýna Budilová, Jaromír Kovárník, Jaroslav Pavelka, Nevenka Atanasoska, Jiří Bumerl, Assunta Florenzano, Tereza Majerovičová, Václav Vondrovský, Michaela Ptáková, Petr Bednář, Lukáš Richtera and Lukáš Kučera

Molecules 2021, 26(11), 3391; https://doi.org/10.3390/molecules26113391 - 03 Jun 2021

Cited by 2 | Viewed by 3622

Abstract

The Late Neolithic palafitte site, Ustie na Drim, in the northern part of Lake Ohrid (North Macedonia), excavated in 1962, offered ceramic fragments of large, flat, elongated pans. These artifacts could be dated by relative chronology to roughly around 5200–5000 BC. According to their shape and technological traits, the ceramic pans were probably used for baking. The attached materials on the surface of studied pan fragments were sampled for consequent chemical and microscopical analyses (i.e., analyses of starch, phytoliths, and microscopic animal remains). An immunological method revealed the presence of pork proteins in samples. The presence of organic residues of animal origin was, moreover, confirmed by the detection of cholesterol using gas chromatography coupled to mass spectrometry. Analysis of detected microscopic botanical objects revealed starch grains of several plants (i.e., oak, cattail, and grasses). An interesting find was the hair of a beetle larva, which could be interpreted contextually as the khapra beetle, a pest of grain and flour. Based on our data, we suppose that the ceramic pans from Ustie na Drim were used for the preparation of meals containing meat from common livestock in combination with cereals and wild plants. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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12 pages, 1671 KiB

Open AccessArticle

Study of Tetrahydroxylated Anthraquinones—Potential Tool to Assess Degradation of Anthocyanins Rich Food

by Lukáš Kučera, Ondřej Kurka, Martin Golec and Petr Bednář

Molecules 2021, 26(1), 2; https://doi.org/10.3390/molecules26010002 - 22 Dec 2020

Cited by 4 | Viewed by 2028

Abstract

Degradation of anthocyanins involves scission of the flavonoid skeleton yielding 2,4,6-trihydroxybenzaldehyde (phloroglucinaldehyde, PGA) and a phenolic acid. However, the process is not finished with the formation of PGA, as the consequent condensation of two PGA molecules providing colored hydroxylated anthraquinones was observed for the first time. This process was studied using a combination of preparative column chromatography, nuclear magnetic resonance, liquid chromatography/high resolution tandem mass spectrometry (LC/HRMS²), and quantum calculations using density functional theory. 1,3,5,7-tetrahydroxyanthraquinone (anthrachrysone) and its isomers were found to rise during heating (95 °C) in a buffered PGA model solution (phosphate buffer, pH 7). These compounds were detected in heated red wine after an increase of its pH value. The concentration of the identified anthrachrysone in the red wine reached 0.01 mg·L⁻¹. Presence of those compounds could therefore indicate involvement of certain steps in the processing of plant materials rich in anthocyanins (e.g., utilization of a higher temperature and/or reduction of acidity) or long-term transformation of anthocyanins (potentially, for instance, in archaeological findings such as wine or fruit residues). Additionally, measurement of wine–soil suspensions proved an increase of their pH to the values suitable for anthocyanin cleavage (neutral to slightly alkaline; reached using soil from archaeologically well-known Bull Rock Cave). Although not found in artificially prepared samples (imitations) or authentic materials so far, according to our results the above mentioned conditions are suitable for the formation of tetrahydroxylated anthraquinone derivatives and their monitoring would be beneficial. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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Review

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34 pages, 1535 KiB

Open AccessReview

A Review on Tetrabromobisphenol A: Human Biomonitoring, Toxicity, Detection and Treatment in the Environment

by Baoji Miao, Salome Yakubu, Qingsong Zhu, Eliasu Issaka, Yonghui Zhang and Mabruk Adams

Molecules 2023, 28(6), 2505; https://doi.org/10.3390/molecules28062505 - 09 Mar 2023

Cited by 4 | Viewed by 2590

Abstract

Tetrabromobisphenol A (TBBPA) is a known endocrine disruptor employed in a range of consumer products and has been predominantly found in different environments through industrial processes and in human samples. In this review, we aimed to summarize published scientific evidence on human biomonitoring, toxic effects and mode of action of TBBPA in humans. Interestingly, an overview of various pretreatment methods, emerging detection methods, and treatment methods was elucidated. Studies on exposure routes in humans, a combination of detection methods, adsorbent-based treatments and degradation of TBBPA are in the preliminary phase and have several limitations. Therefore, in-depth studies on these subjects should be considered to enhance the accurate body load of non-invasive matrix, external exposure levels, optimal design of combined detection techniques, and degrading technology of TBBPA. Overall, this review will improve the scientific comprehension of TBBPA in humans as well as the environment, and the breakthrough for treating waste products containing TBBPA. Full article

(This article belongs to the Special Issue Applied Analytical Chemistry)

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