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Chemometrics for Environmental Analysis

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 5960

Special Issue Editors

CNRS, IMRCP Laboratory, Toulouse University, 31062 Toulouse, France
Interests: analytical chemistry; separation sciences; mass spectrometry; HRMS; food chemistry; environmental chemistry; modeling and chemometrics; quantitative structure–retention relationships; quantitative structure–property relationships
CNRS, IMRCP Laboratory, Toulouse University, 31062 Toulouse, France
Interests: analytical chemistry; DoE; photochemistry; modeling and chemometrics

Special Issue Information

Dear Colleagues,

Analytical chemistry for the environment is a major social issue, for the study of ecosystems or for the analysis of population exposure to micro-pollutants. The specificity of this section of analytical chemistry comes from the varied matrices that are encountered (e.g., animal, plant, soil, humus, water, ocean, sediment, air) and analytes that come from varied chemical families, with variable physicochemical properties. The result is the development of methods in all fields of analytical chemistry: spectrometry (e.g., UV, fluorescence, IR), chromatography (e.g., HPLC, U-HPLC, GC, 2D-LC and GC) and hyphenated techniques using high-resolution mass spectrometry (HRMS), ultra-high-resolution mass spectrometry with Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) and NMR.

The fundamental aspects are essential to these new developments, to allow innovations—particularly in 2D LC or GC. Method validation is also a challenge for these matrices and analytes. The emergence of new types of contaminants, including pharmaceuticals, personal care products, industrial chemicals, cleaning detergents, steroid hormones or micro and nano plastics, arises in combination with new developments, from sample preparation to signal processing.

Chemometrics occupies an important place in analytical chemistry for the environment, to process the sum of data generated by various detection modes. It takes an important place to identify unconventional analytes, or in the study of dissolved organic matter, its evolution or its structure. Chemometrics developments are major in all these areas to identify the key structural or analytical parameters of the environmental analyte.

The objective of this Special Issue is to present the advances in environmental analytical chemistry in all analytical fields that use chemometrics, to propose new strategies that meet regulatory requirements or emerging contaminants, or to search for new active principles for industry which are derived from the environment.

All applications in the fields of environmental analysis will be welcome, as will the fundamental aspects, whether for method development or validation. The objective is to cover all the matrices encountered in the environment and to present a wide range of advances that have recently been obtained in sample preparation, fractionation, LC, GC and mass spectrometry (particularly HRMS). For each of these developments, we are particularly interested in how data processing is integrated into the method: for statistical processing, or upstream (integrating a QbD approach), or in classification, signal processing or structural study. All aspects of chemometrics applied to environmental matrices are welcome, including cluster analysis, principal component analysis, partial least squares, PLS discriminant analysis (PLS-DA), and classification by artificial neural networks.

We welcome the submission of research manuscripts, short communications, and reviews for consideration for publication in this Special Issue of Molecules.

Dr. Jean-Christophe Garrigues
Dr. Florence Benoit-Marquié
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.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

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

  • analytical chemistry
  • environmental chemistry
  • contaminant
  • hyphenated techniques
  • mass spectrometry
  • chromatography
  • spectrometry
  • exposure
  • chemometrics
  • method development
  • structural analysis

Published Papers (4 papers)

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Research

16 pages, 3527 KiB  
Article
Comparison between Variable-Selection Algorithms in PLS Regression with Near-Infrared Spectroscopy to Predict Selected Metals in Soil
by Giovanna Abrantes, Valber Almeida, Angelo Jamil Maia, Rennan Nascimento, Clistenes Nascimento, Ygor Silva, Yuri Silva and Germano Veras
Molecules 2023, 28(19), 6959; https://doi.org/10.3390/molecules28196959 - 06 Oct 2023
Cited by 1 | Viewed by 837
Abstract
Soil is one of the Earth’s most important natural resources. The presence of metals can decrease environmental quality if present in excessive amounts. Analyzing soil metal contents can be costly and time consuming, but near-infrared (NIR) spectroscopy coupled with chemometric tools can offer [...] Read more.
Soil is one of the Earth’s most important natural resources. The presence of metals can decrease environmental quality if present in excessive amounts. Analyzing soil metal contents can be costly and time consuming, but near-infrared (NIR) spectroscopy coupled with chemometric tools can offer an alternative. The most important multivariate calibration method to predict concentrations or physical, chemical or physicochemical properties as a chemometric tool is partial least-squares (PLS) regression. However, a large number of irrelevant variables may cause problems of accuracy in the predictive chemometric models. Thus, stochastic variable-selection techniques, such as the Firefly algorithm by intervals in PLS (FFiPLS), can provide better solutions for specific problems. This study aimed to evaluate the performance of FFiPLS against deterministic PLS algorithms for the prediction of metals in river basin soils. The samples had their spectra collected from the region of 1000–2500 nm. Predictive models were then built from the spectral data, including PLS, interval-PLS (iPLS), successive projections algorithm for interval selection in PLS (iSPA-PLS), and FFiPLS. The chemometric models were built with raw data and preprocessed data by using different methods such as multiplicative scatter correction (MSC), standard normal variate (SNV), mean centering, adjustment of baseline and smoothing by the Savitzky–Golay method. The elliptical joint confidence region (EJCR) used in each chemometric model presented adequate fit. FFiPLS models of iron and titanium obtained a relative prediction deviation (RPD) of more than 2. The chemometric models for determination of aluminum obtained an RPD of more than 2 in the preprocessed data with SNV, MSC and baseline (offset + linear) and with raw data. The metals Be, Gd and Y failed to obtain adequate models in terms of residual prediction deviation (RPD). These results are associated with the low values of metals in the samples. Considering the complexity of the samples, the relative error of prediction (REP) obtained between 10 and 25% of the values adequate for this type of sample. Root mean square error of calibration and prediction (RMSEC and RMSEP, respectively) presented the same profile as the other quality parameters. The FFiPLS algorithm outperformed deterministic algorithms in the construction of models estimating the content of Al, Be, Gd and Y. This study produced chemometric models with variable selection able to determine metals in the Ipojuca River watershed soils using reflectance-mode NIR spectrometry. Full article
(This article belongs to the Special Issue Chemometrics for Environmental Analysis)
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16 pages, 1830 KiB  
Article
Contribution of Reliable Chromatographic Data in QSAR for Modelling Bisphenol Transport across the Human Placenta Barrier
by Clémence A. Gély, Nicole Picard-Hagen, Malika Chassan, Jean-Christophe Garrigues, Véronique Gayrard and Marlène Z. Lacroix
Molecules 2023, 28(2), 500; https://doi.org/10.3390/molecules28020500 - 04 Jan 2023
Cited by 1 | Viewed by 1237
Abstract
Regulatory measures and public concerns regarding bisphenol A (BPA) have led to its replacement by structural analogues, such as BPAF, BPAP, BPB, BPF, BPP, BPS, and BPZ. However, these alternatives are under surveillance for potential endocrine disruption, particularly during the critical period of [...] Read more.
Regulatory measures and public concerns regarding bisphenol A (BPA) have led to its replacement by structural analogues, such as BPAF, BPAP, BPB, BPF, BPP, BPS, and BPZ. However, these alternatives are under surveillance for potential endocrine disruption, particularly during the critical period of fetal development. Despite their structural analogies, these BPs differ greatly in their placental transport efficiency. For predicting the fetal exposure of this important class of emerging contaminants, quantitative structure-activity relationship (QSAR) studies were developed to model and predict the placental clearance indices (CI). The most usual input parameters were molecular descriptors obtained by modelling, but for bisphenols (BPs) with structural similarities or heteroatoms such as sulfur, these descriptors do not contrast greatly. This study evaluated and compared the capacity of QSAR models based either on molecular or chromatographic descriptors or a combination of both to predict the placental passage of BPs. These chromatographic descriptors include both the retention mechanism and the peak shape on columns that reflect specific molecular interactions between solute and stationary and mobile phases and are characteristic of the molecular structure of BPs. The chromatographic peak shape such as the asymmetry and tailing factors had more influence on predicting the placental passage than the usual retention parameters. Furthermore, the QSAR model, having the best prediction capacity, was obtained with the chromatographic descriptors alone and met the criteria of internal and cross validation. These QSAR models are crucial for predicting the fetal exposure of this important class of emerging contaminants. Full article
(This article belongs to the Special Issue Chemometrics for Environmental Analysis)
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13 pages, 1958 KiB  
Article
Characterizing Powdered Activated Carbon Treatment of Surface Water Samples Using Polarity-Extended Non-Target Screening Analysis
by Susanne Minkus, Stefan Bieber and Thomas Letzel
Molecules 2022, 27(16), 5214; https://doi.org/10.3390/molecules27165214 - 16 Aug 2022
Cited by 1 | Viewed by 1188
Abstract
Advanced wastewater treatment such as powdered activated carbon (PAC) reduces the load of organic micropollutants entering the aquatic environment. Since mobile and persistent compounds accumulate in water cycles, treatment strategies need to be evaluated for the removal of (very) polar compounds. Thereby, non-targeted [...] Read more.
Advanced wastewater treatment such as powdered activated carbon (PAC) reduces the load of organic micropollutants entering the aquatic environment. Since mobile and persistent compounds accumulate in water cycles, treatment strategies need to be evaluated for the removal of (very) polar compounds. Thereby, non-targeted analysis gives a global picture of the molecular fingerprint (including these very polar molecules) of water samples. Target and non-target screening were conducted using polarity-extended chromatography hyphenated with mass spectrometry. Samples treated with different types and concentrations of PAC were compared to untreated samples. Molecular features were extracted from the analytical data to determine fold changes, perform a principal component analysis and for significance testing. The results suggest that a part of the polar target analytes was adsorbed but also some byproducts might be formed or desorbed from the PAC. Full article
(This article belongs to the Special Issue Chemometrics for Environmental Analysis)
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17 pages, 4010 KiB  
Article
An Alternative Strategy for Screening and Confirmation of 330 Pesticides in Ground- and Surface Water Using Liquid Chromatography Tandem Mass Spectrometry
by Edgár Tóth, Ádám Tölgyesi, Andrea Simon, Mária Bálint, Xingmao Ma and Virender K. Sharma
Molecules 2022, 27(6), 1872; https://doi.org/10.3390/molecules27061872 - 14 Mar 2022
Cited by 5 | Viewed by 1983
Abstract
The presence of pesticide residues in water is a huge worldwide concern. In this paper we described the development and validation of a new liquid chromatography tandem mass spectrometric (LC-MS/MS) method for both screening and quantification of pesticides in water samples. In the [...] Read more.
The presence of pesticide residues in water is a huge worldwide concern. In this paper we described the development and validation of a new liquid chromatography tandem mass spectrometric (LC-MS/MS) method for both screening and quantification of pesticides in water samples. In the sample preparation stage, the samples were buffered to pH 7.0 and pre-concentrated on polymeric-based cartridges via solid-phase extraction (SPE). Highly sensitive detection was carried out with mobile phases containing only 5 mM ammonium formate (pH of 6.8) as an eluent additive and using only positive ionization mode in MS/MS instrument. Hence, only 200-fold sample enrichment was required to set a screening detection limit (SDL) and reporting limit (RL) of 10 ng/L. The confirmatory method was validated at 10 and 100 ng/L spiking levels. The apparent recoveries obtained from the matrix-matched calibration (5–500 ng/L) were within the acceptable range (60–120%), also the precision (relative standard deviation, RSD) was not higher than 20%. During the development, 480 pesticides were tested and 330 compounds fulfilled the requirements of validation. The method was successfully applied to proficiency test samples to evaluate its accuracy. Moreover, the method robustness test was carried out using higher sample volume (500 mL) followed by automated SPE enrichment. Finally, the method was used to analyze 20 real samples, in which some compounds were detected around 10 ng/L, but never exceeded the assay maximum level. Full article
(This article belongs to the Special Issue Chemometrics for Environmental Analysis)
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