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Miniaturized Sensors in Analytical Spectroscopy/Spectrometry

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

Deadline for manuscript submissions: 30 June 2024 | Viewed by 4634

Special Issue Editors


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Guest Editor
Institute of Analytical Chemistry and Radiochemistry, CCB-Center for Chemistry and Biomedicine, Leopold-Franzens University, Innrain 80-82, 6020 Innsbruck, Austria
Interests: vibrational spectroscopy; near-infrared (NIR) spectroscopy; analytical chemistry; physical chemistry; chemometrics; natural product analysis
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Institute of Analytical Chemistry and Radiochemistry, CCB-Center for Chemistry and Biomedicine, Leopold-Franzens University, Innrain 80-82, 6020 Innsbruck, Austria
Interests: vibrational spectroscopy; analytical chemistry; theoretical spectroscopy; computational methods
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Miniaturized spectrometers have revolutionized analytical spectroscopy/spectrometry by opening up a spectrum of entirely new application niches. On-site capability offered by handheld spectrometers forms particular synergy with the common features of spectroscopic analysis: rapid, cost-effective, non-destructive analysis of variety of samples. Miniaturized sensors have presented a groundbreaking advance in various industries (e.g., pharmaceutical, food), through forensics and security, to agriculture and environmental monitoring, where rapid analysis directly in the field introduces a new quality in analytical routine.

Portable and miniaturized instruments have become recognized and demanded by modern science and industry. The miniaturization has reached most valued physicochemical techniques; e.g., vibrational (NIR, MIR, Raman), electronic (UV-Vis including imaging/computer vision), X-ray fluorescence (XRF), laser-induced breakdown spectroscopy (LIBS), nuclear magnetic resonance (NMR), or mass spectrometry (MS), to mention the most widely adopted ones. Critical advantages over conventional analytical routines make portable spectroscopy and spectrometry preferable in a broad variety of applications, where these sensors are often adopted as the primary analytical/quality control tool.

While portable instruments exhibit key practical advantages, appreciable attention of analytical chemistry is directed toward establishing feasible pathways toward optimization of the framework of successful and reliable application of these instruments. Innovative technology often introduces inevitable trade-offs (e.g. narrower wavelength range, limited resolution expressed), which might be simply expressed as the ‘miniaturization vs. performance’ dilemma.

Hence, systematic feasibility studies aimed at establishing the applicability of these devices are currently immensely actively conducted. In parallel, new concepts emerge in connection with novel miniaturized and portable instrumentation, e.g., multi-band sensors and sensor fusion, airborne (UAV) spectroscopy, developments into innovative data analysis, chemometrics, calibration transfer, or the operating software enabling ease of use for untrained personnel or end customers without professional training of any sort.

This Special Issue collects contributions reporting on the current progress achieved in miniaturization of spectroscopy/spectrometry in all relevant aspects, including technology, feasibility studies, design of methods, data-analytical approaches, and development of new applications.

Dr. Justyna Grabska
Prof. Dr. Christian Huck
Dr. Krzysztof Bernard Bec
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

  • spectroscopy
  • spectrometry
  • analytical chemistry
  • chemometrics
  • data analysis
  • hand-held
  • portable
  • miniaturized

Published Papers (3 papers)

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Research

21 pages, 7013 KiB  
Article
Comparison of Multiple NIR Spectrometers for Detecting Low-Concentration Nitrogen-Based Adulteration in Protein Powders
by Matyas Lukacs, John-Lewis Zinia Zaukuu, George Bazar, Bernhard Pollner, Marietta Fodor and Zoltan Kovacs
Molecules 2024, 29(4), 781; https://doi.org/10.3390/molecules29040781 - 8 Feb 2024
Viewed by 981
Abstract
Protein adulteration is a common fraud in the food industry due to the high price of protein sources and their limited availability. Total nitrogen determination is the standard analytical technique for quality control, which is incapable of distinguishing between protein nitrogen and nitrogen [...] Read more.
Protein adulteration is a common fraud in the food industry due to the high price of protein sources and their limited availability. Total nitrogen determination is the standard analytical technique for quality control, which is incapable of distinguishing between protein nitrogen and nitrogen from non-protein sources. Three benchtops and one handheld near-infrared spectrometer (NIRS) with different signal processing techniques (grating, Fourier transform, and MEM—micro-electro-mechanical system) were compared with detect adulteration in protein powders at low concentration levels. Whey, beef, and pea protein powders were mixed with a different combination and concentration of high nitrogen content compounds—namely melamine, urea, taurine, and glycine—resulting in a total of 819 samples. NIRS, combined with chemometric tools and various spectral preprocessing techniques, was used to predict adulterant concentrations, while the limit of detection (LOD) and limit of quantification (LOQ) were also assessed to further evaluate instrument performance. Out of all devices and measurement methods compared, the most accurate predictive models were built based on the dataset acquired with a grating benchtop spectrophotometer, reaching R2P values of 0.96 and proximating the 0.1% LOD for melamine and urea. Results imply the possibility of using NIRS combined with chemometrics as a generalized quality control tool for protein powders. Full article
(This article belongs to the Special Issue Miniaturized Sensors in Analytical Spectroscopy/Spectrometry)
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19 pages, 3519 KiB  
Article
A Multivariate Analysis-Driven Workflow to Tackle Uncertainties in Miniaturized NIR Data
by Giulia Gorla, Paolo Taborelli and Barbara Giussani
Molecules 2023, 28(24), 7999; https://doi.org/10.3390/molecules28247999 - 7 Dec 2023
Viewed by 999
Abstract
This study focuses on exploring and understanding measurement errors in analytical procedures involving miniaturized near-infrared instruments. Despite recent spreading in different application fields, there remains a lack of emphasis on the accuracy and reliability of these devices, which is a critical concern for [...] Read more.
This study focuses on exploring and understanding measurement errors in analytical procedures involving miniaturized near-infrared instruments. Despite recent spreading in different application fields, there remains a lack of emphasis on the accuracy and reliability of these devices, which is a critical concern for accurate scientific outcomes. The study investigates multivariate measurement errors, revealing their complex nature and the influence that preprocessing techniques can have. The research introduces a possible workflow for practical error analysis in experiments involving diverse samples and instruments. Notably, it investigates how sample characteristics impact errors in the case of solid pills and tablets, typical pharmaceutical samples. ASCA was used for understanding critical instrumental factors and the potential and limitations of the method in the current application were discussed. The joint interpretation of multivariate error matrices and their resume through image histograms and K index are discussed in order to evaluate the impact of common preprocessing methods and to assess their influence on signals. Full article
(This article belongs to the Special Issue Miniaturized Sensors in Analytical Spectroscopy/Spectrometry)
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13 pages, 2338 KiB  
Article
A Rapid Qualitative Screening Method for Isoniazid Tablets Using Handheld NIR Spectrometers in Two Countries
by Matthew Eady, Jonelle Caison, Mohammed Jinnah and David Jenkins
Molecules 2023, 28(12), 4758; https://doi.org/10.3390/molecules28124758 - 14 Jun 2023
Cited by 2 | Viewed by 1954
Abstract
Background: Isoniazid is a leading tuberculosis treating medication. Global supply chains provide essential medicines such as isoniazid to resource-limited areas. Ensuring the safety and efficaciousness of these medicines is essential to public health programs. Handheld spectrometers are becoming increasingly approachable in cost and [...] Read more.
Background: Isoniazid is a leading tuberculosis treating medication. Global supply chains provide essential medicines such as isoniazid to resource-limited areas. Ensuring the safety and efficaciousness of these medicines is essential to public health programs. Handheld spectrometers are becoming increasingly approachable in cost and usability. As supply chains expand, quality compliance screening of essential medications is necessary in site-specific locations. Here, a brand-specific qualitative discrimination analysis of isoniazid is approached by collecting data from two handheld spectrometers in two countries with the intent to build a multi-location quality compliance screening method for a brand of isoniazid. Methods: Two handheld spectrometers (900–1700 nm) were used to collect spectra from five manufacturing sources (N = 482) in Durham, North Carolina, USA, and Centurion, South Africa. A qualitative brand differentiation method was established from both locations by applying a Mahalanobis distance thresholding method as a measure of assessing similarity. Results: Combining data from both locations resulted in a 100% classification accuracy, at both locations, for brand ‘A’ and resulted in the four other brands classifying as dissimilar. Bias was found between sensors in terms of resulting Mahalanobis distances, but the classification method proved to be robust enough to accommodate. Several spectral peaks found in isoniazid references appear within the 900–1700 nm range, as well as variation in the excipients per manufacturer. Conclusions: Results show promise for compliance screening isoniazid as well as other tablets in multiple geographic locations using handheld spectrometers. Full article
(This article belongs to the Special Issue Miniaturized Sensors in Analytical Spectroscopy/Spectrometry)
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