Chemosensors

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13 pages, 2317 KiB

Open AccessArticle

A Rapid and Interference-Resistant Formaldehyde Detection Method Based on Surface-Enhanced Raman Spectroscopy with a Reaction-Induced Self-Amplification Strategy

by Chen Wang, Yanli Gao, Xinrong Qiu, Lifang Nie, Yang Liu, Rigui Zhou, Hongpeng Wang and Shengjun Xiong

Chemosensors 2024, 12(7), 132; https://doi.org/10.3390/chemosensors12070132 - 8 Jul 2024

Viewed by 346

Abstract

Formaldehyde is widely utilized across various industries such as food, textiles, and leather, yet its presence raises significant health concerns due to its irritation and carcinogenicity. Numerous methods have been developed to probe it in solution and gas states. Among them, absorption spectroscopy-based [...] Read more.

Formaldehyde is widely utilized across various industries such as food, textiles, and leather, yet its presence raises significant health concerns due to its irritation and carcinogenicity. Numerous methods have been developed to probe it in solution and gas states. Among them, absorption spectroscopy-based methods commonly employed. However, these methods require complex preprocessing for colored solutions to avoid interference. In response to this challenge, a novel interference-resistant detection kit leveraging surface-enhanced Raman spectroscopy (SERS) coupled with reaction-induced self-amplification for rapid and direct detection of formaldehyde was developed. The kit needed only ten minutes and achieved a limit of detection lower than 10⁻⁴ μg/mL with a handheld Raman spectrometer. Thanks to the kit’s reaction with formaldehyde, colloidal nanoparticles were linked to form “hot-spots” to further enhance the SERS signals. The signal demonstrated outstanding resistance to interference, including different dyes, ensuring a practical tool for direct detection of formaldehyde in complex solutions. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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23 pages, 7107 KiB

Open AccessArticle

Profiling of Organosulfur Compounds in Onions: A Comparative Study between LC-HRMS and DTD-GC-MS

by Ana V. González-de-Peredo, Alicia Maroto, Gerardo F. Barbero and Antony Memboeuf

Chemosensors 2024, 12(7), 130; https://doi.org/10.3390/chemosensors12070130 - 6 Jul 2024

Viewed by 361

Abstract

Onions are known not only for their culinary importance but also for their nutritional and health-promoting properties. Both properties are closely linked to their content of organosulfur compounds, which account for up to 5% of the dry weight of an onion. Given the [...] Read more.

Onions are known not only for their culinary importance but also for their nutritional and health-promoting properties. Both properties are closely linked to their content of organosulfur compounds, which account for up to 5% of the dry weight of an onion. Given the importance of these compounds, suitable analytical methods are required for their study. Two techniques should be highlighted in this context: gas chromatography coupled to mass spectrometry (GC-MS), and liquid chromatography coupled to mass spectrometry (LC-MS). In this study, eight different onion varieties were analyzed using two distinct analytical techniques: direct thermal desorption–gas chromatography–mass spectrometry (DTD-GC-MS) and high-resolution mass spectrometry (HRMS) on an LC-ESI-QqTOF instrument. Each method identified different organosulfur compounds, with LC-HRMS targeting 15 non-volatile compounds, such as cysteine sulfoxides, and GC-MS targeting 18 volatiles, such as disulfides and trisulfides. The results obtained were studied using Pearson correlations and principal component analysis. No precise correlation was found between the initial organosulfur compounds in onions and their hydrolysates. Consequently, although GC is one of the most employed techniques in the scientific literature, the use of LC-HRMS or a combination of both techniques may offer a more comprehensive and accurate description of the metabolomic profile of onions. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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18 pages, 4842 KiB

Open AccessArticle

Quantitative Analysis of Chlorogenic Acid during Coffee Roasting via Raman Spectroscopy

by Deborah Herdt, Tobias Teumer, Shaun Paul Keck, Thomas Kunz, Victoria Schiwek, Sarah Kühnemuth, Frank-Jürgen Methner and Matthias Rädle

Chemosensors 2024, 12(6), 106; https://doi.org/10.3390/chemosensors12060106 - 9 Jun 2024

Viewed by 673

Abstract

Tracking coffee roasting at an industrial scale for quality control is challenging. Bean color is a practical gauge for monitoring and regulating the process but only occurs before and after the process. This study highlights the feasibility of monitoring the process throughout using [...] Read more.

Tracking coffee roasting at an industrial scale for quality control is challenging. Bean color is a practical gauge for monitoring and regulating the process but only occurs before and after the process. This study highlights the feasibility of monitoring the process throughout using Raman spectroscopy. Strecker degradation and the Maillard reaction contribute to various aromatic compounds that can serve as markers in quality monitoring. Among these are chlorogenic acids (CGAs), recognized as pivotal factors determining the desired aroma. Here, drum and fluidized bed roaster processes were monitored, capitalizing on the chemical alterations induced by high temperatures (140–200 °C), particularly through the Maillard reaction. These chemical changes manifest in the scattered light signal. For real-time monitoring, Raman spectra were taken every 10 ms in selected ranges, with an average calculated every second. Utilizing a calibration matrix from a High-Pressure Liquid Chromatography (HPLC) method, CGA concentration becomes the control variable for assessing roasting progress. This study reveals the potential of Raman spectroscopy for tracking CGA during roasting. It establishes a correlation between inelastic scattered light and CGA validated through laboratory measurements and fixed roasting conditions, resulting in a theoretical CGA concentration that can be used as a process termination criterion. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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12 pages, 3949 KiB

Open AccessArticle

Identification of the Beverage Sotol Adulterated with Ethylene Glycol Using UV-Vis Spectroscopy and Artificial Neural Networks

by Fernando Gaxiola, Jesús Javier Leal, Alain Manzo-Martínez, Iván Salmerón, José Rafael Linares-Morales and Roberto Narro-García

Chemosensors 2024, 12(3), 46; https://doi.org/10.3390/chemosensors12030046 - 13 Mar 2024

Viewed by 1546

Abstract

Sotol is a traditional distilled alcoholic beverage produced in Mexico and the United States. Unfortunately, local authorities have detected that these beverages are sometimes adulterated with toxic substances such as ethylene glycol. This illegal practice of adulteration is dangerous and can cause serious [...] Read more.

Sotol is a traditional distilled alcoholic beverage produced in Mexico and the United States. Unfortunately, local authorities have detected that these beverages are sometimes adulterated with toxic substances such as ethylene glycol. This illegal practice of adulteration is dangerous and can cause serious health problems for the end consumers. In this work, an alternative, reliable, and rapid method is presented for identifying the presence of ethylene glycol in sotol samples using UV-Vis spectroscopy and neural networks with an accuracy of up to 100%. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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18 pages, 7382 KiB

Open AccessArticle

Near Infrared and UV-Visible Spectroscopy Coupled with Chemometrics for the Characterization of Flours from Different Starch Origins

by Samuele Pellacani, Marco Borsari, Marina Cocchi, Alessandro D’Alessandro, Caterina Durante, Giulia Farioli and Lorenzo Strani

Chemosensors 2024, 12(1), 1; https://doi.org/10.3390/chemosensors12010001 - 22 Dec 2023

Viewed by 1864

Abstract

This work tested near-infrared (NIR) and UV-visible (UV-Vis) spectroscopy coupled with chemometrics to characterize flours from different starch origins. In particular, eighteen starch-containing flours (e.g., type 00 flour, rye, barley, soybean, chestnut, potato, spelt, buckwheat, oat, millet, rice, durum wheat, amaranth, chickpea, sesame, [...] Read more.

This work tested near-infrared (NIR) and UV-visible (UV-Vis) spectroscopy coupled with chemometrics to characterize flours from different starch origins. In particular, eighteen starch-containing flours (e.g., type 00 flour, rye, barley, soybean, chestnut, potato, spelt, buckwheat, oat, millet, rice, durum wheat, amaranth, chickpea, sesame, corn, hemp and sunflower flours) were analyzed with a twofold objective: chemically characterizing the investigated flours and laying the groundwork for the development of a fast and suitable method that can identify the botanical source of starch in food. This could ensure ingredient traceability and aid in preventing/detecting food fraud. Untargeted approaches were used for this study, involving the simultaneous acquisition of a large amount of chemical information (UV-Vis on extracted starch and NIR signals on raw flours) coupled with chemometric techniques. UV-VIS spectra were acquired between 225 and 800 nm after sample pretreatment to extract starch. NIR spectra were acquired between 900 and 1700 nm using a poliSPEC NIRe portable instrument on the flours without any kind of pretreatments. An initial exploratory investigation was conducted using principal component analysis and cluster analysis, obtaining interesting preliminary information on patterns among the investigated flours. In particular, the UV-Vis model successfully discerned samples such as potato, chestnut, sunflower, durum wheat, sesame, buckwheat, rice, corn, spelt and 00-type flours. PCA model results obtained from the analysis of NIR spectra also provided comparable results with the UV-Vis model, particularly highlighting the differences observed between hemp and potato flours with soybean flour. Some similarities were identified between other flours, such as barley and millet, rye and oats, and chickpea and amaranth. Therefore, some flour samples underwent surface analysis via scanning electron microscope (SEM) using the Nova NanoSEM 450 to detect distinctive morphology. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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16 pages, 4553 KiB

Open AccessArticle

Pyrogallol Detection Based on the Cobalt Metal–Organic Framework of Nanomaterial-Enhanced Chemiluminescence

by Yanran Wang, Zhiqiang Wang, Yincheng Liu, Zixuan Liu, Zhan Gao, Kuangjun Li, Dajun Zhao, Jing Wu and Xuanhe Liu

Chemosensors 2023, 11(7), 395; https://doi.org/10.3390/chemosensors11070395 - 14 Jul 2023

Viewed by 1303

Abstract

The cobalt metal–organic framework (Co-MOF) is a kind of crystalline porous material within a periodic network structure, which is formed via the self-assembly of a Co metal center and a bridged organic ligand. In this paper, a Co-MOF was facilely synthesized via an [...] Read more.

The cobalt metal–organic framework (Co-MOF) is a kind of crystalline porous material within a periodic network structure, which is formed via the self-assembly of a Co metal center and a bridged organic ligand. In this paper, a Co-MOF was facilely synthesized via an ultrasonic method and applied to enhance the chemiluminescence (CL) emission of the NaIO₄-H₂O₂ system. The synthesized Co-MOF was nanosheet-like in nature and stacked in 2–3-micrometer flower shapes. Compared to the NaIO₄-H₂O₂ system without a Co-MOF, the CL intensity of the Co-MOF-NaIO₄-H₂O₂ system was enhanced about 70 times. This CL mechanism was determined to be a result of the synergistic effects of chemiluminescence resonance energy transfer (CRET) and electron–hole annihilation (EHA). The Co-MOF not only acted as a catalyst to accelerate the generation of reactive oxygen species in the CL reaction, but also worked as an emitter to further enhance the CL. Based on the Co-MOF-NaIO₄-H₂O₂ system, a highly sensitive CL analysis method was established for pyrogallol (PG) detection. Addition of PG into the CL system generated ¹O₂*, which could transfer energy to the Co-MOF and further enhance the CL response. The enhanced CL was linear with the PG concentration. The CL analysis method exhibited a linear range of 1 × 10⁻⁴ M to 1 × 10⁻⁷ M, as well as having a linear correlation coefficient of 0.9995 and a limit of detection of (S/N = 3) of 34 nM. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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11 pages, 1748 KiB

Open AccessArticle

Coal Calorific Value Detection Technology Based on NIRS-XRF Fusion Spectroscopy

by Jiaxuan Li, Rui Gao, Yan Zhang, Shuqing Wang, Lei Zhang, Wangbao Yin and Suotang Jia

Chemosensors 2023, 11(7), 363; https://doi.org/10.3390/chemosensors11070363 - 28 Jun 2023

Cited by 2 | Viewed by 1390

Abstract

Calorific value is an important index for evaluating coal quality, and it is important to achieve the rapid detection of calorific value to improve production efficiency. In this paper, a calorific value detection method based on NIRS-XRF fusion spectroscopy is proposed, which utilizes [...] Read more.

Calorific value is an important index for evaluating coal quality, and it is important to achieve the rapid detection of calorific value to improve production efficiency. In this paper, a calorific value detection method based on NIRS-XRF fusion spectroscopy is proposed, which utilizes NIRS to detect organic functional groups and XRF to detect inorganic ash-forming elements in coal. NIRS, XRF and NIRS-XRF fusion spectrum were separately used to establish partial least squares (PLS) regression models for coal calorific value, and better prediction performance was obtained by using fusion spectrum (the determination coefficient of calibration set (R²) was 0.98, the root mean square error of prediction set (RMSE_P) was 0.19 MJ/kg, the average relative deviation for prediction (MARD_P) was 0.95%). The variable selection is very important for model performance. The effective variables were extracted using Pearson correlation coefficients to further optimize the prediction model, and the evaluation indexes of the optimized model are R² = 0.99, RMSE_P = 0.16 MJ/kg and MARD_P = 0.70%. In addition, the repeatability of the proposed method was briefly evaluated. The results show that the proposed method is an effective analysis method to detect the calorific value of coal, which provides a new idea and technique for coal quality detection. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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13 pages, 5253 KiB

Open AccessArticle

LIBS-MLIF Method: Stromatolite Phosphorite Determination

by Hongpeng Wang, Yingjian Xin, Peipei Fang, Jianjun Jia, Liang Zhang, Sicong Liu and Xiong Wan

Chemosensors 2023, 11(5), 301; https://doi.org/10.3390/chemosensors11050301 - 19 May 2023

Cited by 1 | Viewed by 1501

Abstract

The search for biominerals is one of the core targets in the deep space exploration mission. Stromatolite phosphorite is a typical biomineral that preserves early life on Earth. The enrichment of phosphate is closely related to microorganisms and their secretions. Laser-induced breakdown spectroscopy [...] Read more.

The search for biominerals is one of the core targets in the deep space exploration mission. Stromatolite phosphorite is a typical biomineral that preserves early life on Earth. The enrichment of phosphate is closely related to microorganisms and their secretions. Laser-induced breakdown spectroscopy (LIBS) has become an essential payload in deep space exploration with the ability to analyze chemical elements remotely, rapidly, and in situ. This paper aims to evaluate the rapid identification of biological and non-biological minerals through a remote LIBS payload. LIBS is used for element analysis and mineral classification determination, and molecular laser-induced fluorescence (MLIF) is used to detect halogenated element F to support the existence of fluorapatite. This paper analyzes the LIBS-MLIF spectral characteristics of stromatolites and preliminarily evaluates the feasibility of P element quantification. The results show that LIBS technology can recognize biological and non-biological signals. This discovery is significant because it is not limited to detecting and analyzing element composition. It can also realize the detection of molecular spectrum based on selective extraction of CaF molecule. Therefore, the LIBS payload still has the potential to search for biomineral under the condition of adjusting the detection strategy. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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13 pages, 3591 KiB

Open AccessArticle

Luminescent Metal-Organic Framework with 2,1,3-Benzothiadiazole Units for Highly Sensitive Gossypol Sensing

by Dmitry I. Pavlov, Xiaolin Yu, Alexey A. Ryadun, Vladimir P. Fedin and Andrei S. Potapov

Chemosensors 2023, 11(1), 52; https://doi.org/10.3390/chemosensors11010052 - 7 Jan 2023

Cited by 8 | Viewed by 1978

Abstract

A new metal–organic framework based on cadmium(II) cations, di(p-carboxyphenyl)sulphone and 4,7-di(imidazol-1-yl)-2,1,3-benzothiadiazole was prepared, and its crystal structure was determined using single-crystal XRD analysis. MOF demonstrated bright luminescence with a maximum near 500 nm and quantum yield reaching 20%. In addition, this MOF demonstrated [...] Read more.

A new metal–organic framework based on cadmium(II) cations, di(p-carboxyphenyl)sulphone and 4,7-di(imidazol-1-yl)-2,1,3-benzothiadiazole was prepared, and its crystal structure was determined using single-crystal XRD analysis. MOF demonstrated bright luminescence with a maximum near 500 nm and quantum yield reaching 20%. In addition, this MOF demonstrated sensing properties towards antibiotics and a toxic natural polyphenol gossypol through effective luminescence quenching in an ethanol suspension. The determined detection limit for gossypol was among the lowest reported so far (0.65 µM), and did not significantly change in the interference experiments with cottonseed oil as background, indicating the possibility of using this MOF as a sensor for the detection and determination of gossypol in real-life samples. Full article

(This article belongs to the Special Issue Advanced Spectroscopy Technology for Chemical Qualitative and Quantitative Analysis)

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