Field Of Analytical Chemistry Research Articles

Ion-Selective Electrodes with Solid Contact Based on Composite Materials: A Review.

Potentiometric sensors are the largest and most commonly used group of electrochemical sensors. Among them, ion-selective electrodes hold a prominent place. Since the end of the last century, their re-development has been observed, which is a consequence of the introduction of solid contact constructions, i.e., electrodes without an internal electrolyte solution. Research carried out in the field of potentiometric sensors primarily focuses on developing new variants of solid contact in order to obtain devices with better analytical parameters, and at the same time cheaper and easier to use, which has been made possible thanks to the achievements of material engineering. This paper presents an overview of new materials used as a solid contact in ion-selective electrodes over the past several years. These are primarily composite and hybrid materials that are a combination of carbon nanomaterials and polymers, as well as those obtained from carbon and polymer nanomaterials in combination with others, such as metal nanoparticles, metal oxides, ionic liquids and many others. Composite materials often have better mechanical, thermal, electrical, optical and chemical properties than the original components. With regard to their use in the construction of ion-selective electrodes, it is particularly important to increase the capacitance and surface area of the material, which makes them more effective in the process of charge transfer between the polymer membrane and the substrate material. This allows to obtain sensors with better analytical and operational parameters. Brief characteristics of electrodes with solid contact, their advantages and disadvantages, as well as research methods used to assess their parameters and analytical usefulness were presented. The work was divided into chapters according to the type of composite material, while the data in the table were arranged according to the type of ion. Selected basic analytical parameters of the obtained electrodes have been collected and summarized in order to better illustrate and compare the achievements that have been described till now in this field of analytical chemistry, which is potentiometry. This comprehensive review is a compendium of knowledge in the research area of functional composite materials and state-of-the-art SC-ISE construction technologies.

The “umbrella of tolerance”: Nanobodies-armed photothermal lateral flow immunoassay for the detection of staphylococcal enterotoxin B

Improving the stability and sensitivity of lateral flow immunoassay (LFIA) is an eternal theme in the field of analytical chemistry, and the recent emergence of new molecular recognition element (MRE) and various detection signal offer potential biological and technical possibilities. Here, we innovatively report a nanobodies (Nbs)-armed photothermal lateral flow immunoassay (NLFIA) in which Nbs act as the “umbrella of tolerance”, greatly improving the stability of LFIA. Meanwhile, this is complemented by Au core-petal nanoparticles (CPNs), a photothermal material synthesized by a polydopamine (PDA)-assisted two-step method, to enhance the sensitivity of the readable signal. Following proof of concept in staphylococcal enterotoxin B (SEB), we find that the novel NLFIA not only “suits the case” to improve the tolerance of the strips to the detection environment and the specificity of the target, but also increases the accuracy and comprehensibility of the analysis results on the premise of ensuring the detection sensitivity. The detection limit of NLFIA is 1.68 ng mL−1 (colorimetric mode) and 0.58 ng mL−1 (photothermal mode), which is 25-fold lower than gold standard approach (14.80 ng mL−1). In addition, the proposed method is successfully applied to the detection of SEB in food with high accuracy. This study integrates the novel MRE with photothermal LFIA to provide a reference for the development of a more sensitive and stable platform for the detection of foodborne contaminants.

Construction of an electrochemical sensor for detection of nitrite by gold nanoparticles immobilized on biochar

This study presents a novel electrochemical sensor for the sensitive and selective detection of nitrite, based on gold nanoparticles (AuNPs) immobilized on biochar (BC). The BC/Au composite material was synthesized through a simple and cost-effective process and was characterized by various techniques to confirm its successful formation. The composite was then utilized to modify a fluorine-doped tin oxide (FTO) electrode, which served as the sensing platform. The sensor demonstrated remarkable sensitivity, selectivity, and stability towards nitrite detection, with a wide linear range and a low detection limit. The performance of the sensor was also evaluated using real water samples, showing good reproducibility and applicability for practical applications in environmental monitoring and food safety. This study provides an innovative approach for the development of electrochemical sensors based on BC/Au composites, contributing to the field of analytical chemistry.

Cover: Journal of the Chinese Chemical Society 6/2023

This memorial issue is a collection of papers that showcase the diverse research interests of the late Professor King‐Chuen Lin (1953 – 2022) in the fields of physical chemistry, analytical chemistry, biophysics, and material chemistry. These papers have been contributed by Prof. Lin's friends, colleagues, and former group members. The global chemistry community deeply mourns the loss of Prof. Lin, and through this special issue, the invited contributors aim to honor his memory.image

Determination of hexanal and heptanal in saliva samples by an adapted magnetic headspace adsorptive microextraction for diagnosis of lung cancer

In this work, an analytical method for the determination of two endogenous aldehydes (hexanal and heptanal) as lung cancer biomarkers in saliva samples is presented for the first time. The method is based on a modification of magnetic headspace adsorptive microextraction (M–HS–AME) followed by gas chromatography coupled to mass spectrometry (GC-MS). For this purpose, an external magnetic field generated by a neodymium magnet is used to hold the magnetic sorbent (i.e., CoFe2O4 magnetic nanoparticles embedded into a reversed-phase polymer) in the headspace of a microtube to extract the volatilized aldehydes. Subsequently, the analytes are desorbed in the appropriate solvent and the extract is injected into the GC-MS system for separation and determination. Under the optimized conditions, the method was validated and showed good analytical features in terms of linearity (at least up to 50 ng mL−1), limits of detection (0.22 and 0.26 ng mL−1 for hexanal and heptanal, respectively), and repeatability (RSD ≤12%). This new approach was successfully applied to saliva samples from healthy volunteers and those with lung cancer, obtaining notably differences between both groups. These results reveal the prospect of the method as potential diagnostic tool for lung cancer by saliva analysis. This work contributes to the Analytical Chemistry field presenting a double novelty: on the one hand, the use of M–HS–AME in bioanalysis is unprecedentedly proposed, thus expanding the analytical potential of this technique, and, on the other hand, the determination of hexanal and heptanal is carried out in saliva samples for the first time.

Green profile tools: Current status and future perspectives

The idea of Green Chemistry began to take shape in an increasingly important way starting in the 90 s when the impact of chemical products and processes began to be critically evaluated. In the analytical chemistry field, green chemistry represents an essential factor to consider whenever a laboratory procedure is planned. Therefore, from the start it is necessary examine not only green chemistry (GC) but also green analytical chemistry (GAC). The impact of the GAC on publications shows how the trend has seen an exponential increase from 1995 to 2018. From here, it is evident how the GAC is increasingly essential in the analytical chemist work who needs uniform, impartial, and standardized tools and elements to evaluate the "green profile" of the procedures, also in order to perform a direct comparison between methods and procedures. The purpose of this review is to report, compare, and critically evaluate the tools available today, such as Life Cycle Assessment (LCA), National Environmental Methods Index (NEMI), Analytical Eco-Scale, Green Analytical Procedure Index (GAPI) and ComplexGAPI, RGB (Red Green Blue) and White Analytical Chemistry (WAC) models, hexagon-CALIFICAMET, and finally Analytical GREEnness Metric approach (AGREE) and AGREEprep. This comparison was performed in the text after a short introduction to the concepts and principles related explicitly to GC, GAC, and Green Sample Preparation (GSP).

Preparation of Magnetic Superhydrophilic Imprinted Nanocomposite Resin and its Application in the Extraction of Chlorophenols in Water

AbstractFabricating hydrophilic imprinted materials with eminent aqueous recognition capacity is a bottleneck problem in imprinting field. Herein, a magnetic superhydrophilic imprinted nanocomposite resin (MWNTs@MIR) was first fabricated on magnetic multi walled carbon nanotube with 2,4,6‐trichlorophenol as virtual template, 3‐aminophenol as functional monomer and glyoxylic acid as crosslinking monomer. Via employing MWNTs@MIR as adsorbent and combining with magnetic solid‐phase extraction, the effective enrichment of chlorophenols (CPs) in water is realized. The SEM, TEM, FTIR, XRD and other characterizations confirm that the MWNTs@MIR has been successfully prepared and exhibits excellent magnetism (separated by external magnet within 30 s) and superhydrophilicity (water contact angle 0°). Under optimized extraction conditions, MWNTs@MIR can be directly employed for rapid and efficient extraction of four CPs in water (the extraction recoveries reach 78 %–92 %), and exhibits excellent selectivity (the extraction efficiency of MWNTs@MIR for the four CPs is evidently higher than that of the corresponding non‐imprinted material and reference compound) and stability (the recoveries of CPs did not significantly decrease after 5 cycles). The research provided a novel, easy and economical route for constructing hydrophilic imprinted materials to realize efficient extraction of CPs in water, and has potential application in the field of sample pretreatment and analytical chemistry.

A Novel Minidumbbell DNA-Based Sensor for Silver Ion Detection.

Silver ion (Ag+) is one of the most common heavy metal ions that cause environmental pollution and affect human health, and therefore, its detection is of great importance in the field of analytical chemistry. Here, we report an 8-nucleotide (nt) minidumbbell DNA-based sensor (M-DNA) for Ag+ detection. The minidumbbell contained a unique reverse wobble C·C mispair in the minor groove, which served as the binding site for Ag+. The M-DNA sensor could achieve a detection limit of 2.1 nM and sense Ag+ in real environmental samples with high accuracy. More importantly, the M-DNA sensor exhibited advantages of fast kinetics and easy operation owing to the usage of an ultrashort oligonucleotide. The minidumbbell represents a new and minimal non-B DNA structural motif for Ag+ sensing, allowing for the further development of on-site environmental Ag+ detection devices.

Semiconductor/Carbon Quantum Dot-based Hue Recognition Strategy for Point of Need Testing: A Review.

The requirement to establish novel methods for visual detection is attracting attention in many application fields of analytical chemistry, such as, healthcare, environment, agriculture, and food. The research around subjects like "point-of-need", "hue recognition", "paper-based sensor", "fluorescent sensor", etc. has been always aimed at the opportunity to manufacture convenient and fast-response devices to be used by non-specialists. It is possible to achieve economic rationality and technical simplicity for optical sensing toward target analytes through introduction of fluorescent semiconductor/carbon quantum dot (QD) and paper-based substrates. In this Review, the mechanisms of anthropic visual recognition and fluorescent visual assays, characteristics of semiconductor/carbon QDs and ratiometric fluorescence test paper, and strategies of semiconductor/carbon QD-based hue recognition are described. We cover latest progress in the development and application of point-of-need sensors for visual detection, which is based on a semiconductor/carbon quantum dot-based hue recognition strategy generated by ratiometric fluorescence technology.

Array Point Discharge as Enhanced Tandem Excitation Source for Miniaturized Optical Emission Spectrometer.

A new compact tandem excitation source was designed and constructed by using an array point discharge (ArrPD) microplasma for a miniaturized optical emission spectrometer through coupling a hydride generation (HG) unit as a sample introduction device. Three pairs of point discharges were arranged in sequence in a narrow discharge chamber to construct the ArrPD microplasma, for improved excitation capability owing to the serial excitation. Besides, the discharge plasma region was greatly enlarged, therefore, more gaseous analytes could be intercepted to enter into the microplasma for sufficient excitation, for improved excitation efficiency and OES signal. To better understand the effectiveness of the proposed ArrPD source, a new instrument for simultaneous detection of atomic emission and absorption spectral responses was also proposed, designed, and constructed to reveal the excitation and enhancement process in the discharge chamber. Under the optimized conditions, the limits of detection (LODs) of As, Ge, Hg, Pb, Sb, Se, and Sn were 0.7, 0.4, 0.05, 0.7, 0.3, 2, and 0.08 μg L-1, respectively, and the relative standard deviations (RSDs) were all less than 4%. Compared with a commonly used single point discharge microplasma source, the analytical sensitivities of these seven elements were improved by 3-6-fold. Certified Reference Materials (CRMs) were successfully analyzed with this miniaturized spectrometer, which features low power, compactness, portability, and high detectability, and is thereby a great prospect in the field of elemental analytical chemistry.

Dual-comb optical activity spectroscopy for the analysis of vibrational optical activity induced by external magnetic field

Optical activity (OA) spectroscopy is a powerful tool to characterize molecular chirality, explore the stereo-specific structure and study the solution-state conformation of biomolecules, which is widely utilized in the fields of molecular chirality, pharmaceutics and analytical chemistry. Due to the considerably weak effect, OA spectral analysis has high demands on measurement speed and sensitivity, especially for organic biomolecules. Moreover, gas-phase OA measurements require higher resolution to resolve Doppler-limited profiles. Here, we show the unmatched potential of dual-comb spectroscopy (DCS) in magnetic optical activity spectroscopy (MOAS) of gas-phase molecules with the resolution of hundred-MHz level and the high-speed measurement of sub-millisecond level. As a demonstration, we achieved the rapid, high-precision and high-resolution MOAS measurement of the nitrogen dioxide {upsilon }_{1}+{upsilon }_{3} band and the nitric oxide overtone band, which can be used to analyze fine structure of molecules. Besides, the preliminary demonstration of liquid-phase chiroptical activity (as weak as 10−5) has been achieved with several seconds of sampling time, which could become a routine approach enabling ultrafast dynamics analysis of chiral structural conformations.

Engineering Rational SERS Nanotags for Parallel Detection of Multiple Cancer Circulating Biomarkers

Precision cancer medicine necessitates a personalized treatment plan for each individual patient. Given cancer’s heterogeneity and dynamic nature, the plot of patient-specific signatures composed of multiple cancer circulating biomarkers is useful to reveal the complete tumor landscape for guiding precision medicine. As an emerging new technology, surface-enhanced Raman scattering (SERS) shows the intrinsic advantage of performing multiplexed detection with the extremely narrow Raman spectral line widths. In this review, we first discuss the design principle of SERS nanotags to enable the detection of multiple circulating biomarkers, highlighting the important roles of plasmonic nanostructures and triple bond-modulated Raman reporters. Following this, we detail the use of isotropic and anisotropic nanostructures as SERS enhancement substrates for amplifying Raman signals in multi-biomarker detection. Furthermore, we present the triple bond-modulated molecules as Raman reporters in SERS nanotags to expand the multiplexing capability for biomarker measurements. Finally, we offer critical insights into the challenges and perspectives of SERS nanotags for cancer diagnosis, particularly from the aspect of future clinical transition. It is expected that this review can facilitate the design of more functional SERS nanotags with high sensitivity and multiplexing capability to assist early and accurate cancer screening. We also believe our review will be of interest in the fields of molecular imaging, biomedicine, and analytical chemistry.

Perspective on Aggregation-induced Emission (AIE) Materials for Pathogen Detection

Abstract: The rapid and accurate identification of pathogens plays a crucial role in clinical practice, which helps to prevent, control, and treat pathogenic infections at the initial stage. The current available technologies for pathogen detection appear to be inadequate in dealing with cases such as COVID-19. More importantly, the frequent emergence of drug-resistant bacteria is gradually rendering the existing therapeutic options ineffective. Efforts are urgently required to focus on the development of diagnostic systems for point-of-care (POC) detection and high-throughput pathogen identification. Since 2001, a new class of aggregation-induced emission luminogens (AIEgens) with good photostability, high sensitivity, and improved signal-to-noise ratio has emerged as powerful fluorescent tools for various biosensing and cell imaging. Based on the unique fluorescence of AIEgens that becomes stronger upon aggregation, naked-eye detection in turn-on mode has gained a speedy development. A timely overview can not only provide a summary of the advances and challenges of AIEgens in pathogen detection but also offer systematic ideas for future developments. There are also expectations for in-depth interdisciplinary research in the field of analytical chemistry and microbiology.

Electromagnetic Forces and Torques: From Dielectrophoresis to Optical Tweezers.

Electromagnetic forces and torques enable many key technologies, including optical tweezers or dielectrophoresis. Interestingly, both techniques rely on the same physical process: the interaction of an oscillating electric field with a particle of matter. This work provides a unified framework to understand this interaction both when considering fields oscillating at low frequencies─dielectrophoresis─and high frequencies─optical tweezers. We draw useful parallels between these two techniques, discuss the different and often unstated assumptions they are based upon, and illustrate key applications in the fields of physical and analytical chemistry, biosensing, and colloidal science.

Hydraulic-electric analogy for design and operation of microfluidic systems.

Microfluidic systems have been investigated as practical tools in the fields of biomedical engineering, analytical chemistry, materials science, and biological research. Yet the widespread applications of microfluidic systems have been hindered by the complexity of microfluidic design and the reliance on bulky external controllers. Hydraulic-electric analogy provides a powerful method to design and operate microfluidic systems with minimal requirement of control equipment. Here, we summarize recent development of microfluidic components and circuits based on the hydraulic-electric analogy. In a manner similar to electric circuits, microfluidic analogue circuits with a continuous flow or pressure input actuate fluids in a predetermined way to enable singular tasks such as flow- or pressure-driven oscillators. Microfluidic digital circuits consisting of logic gates are activated by a programmable input to perform complex tasks including on-chip computation. In this review, the design principles and applications of a variety of microfluidic circuits are overviewed. The challenges and future directions of the field are also discussed.

Gate-Controlled Chiral Recognition and Spin Assessment with All-Electric Hybrid Quantum Wire-Based Transistors.

The search for inexpensive and all-electric tunable methods for portable and fast recognition and discrimination between various chiral enantiomers, mainly those found in the gas phase, has been one of the most challenging tasks in the field of analytical chemistry. The current article reports on a chiral sensitive electric architecture (CSEA) of a helical polyaniline (PANI)@carbon nanotube (CNT) hybrid quantum-wire based field effect transistor (FET) platform. The CSEA architecture exhibits gate-controlled-channel-chirality modulation for the selective distinction of Limonene (S(+)/R(-)) at ≈12V intervals. Typical gate-modulated selectivity of S(+)-Limonene and R(-)-Limonene using two opposite helically turned hybrids, namely as,S-PANI@CNT and R-PANI@CNT are 6.5 and 2.8, respectively. Theoretical analysis and modelling relates the gas-phase chiral quantum probe with spin-channel modulation in CNT byRashba spin-orbit interaction. This is achieved by applied gate voltage, CNT's unique curved surface, adsorbed chiral adatom induced scattering center on the curved graphitic lattice and helicoid field from a synthetically prepared helical PANI@CNT hybrid interface.

PROJECT-BASED LEARNING PADA MATA KULIAH KIMIA ANALITIK DASAR MENGGUNAKAN YOUTUBE UNTUK PENINGKATAN KETERAMPILAN ABAD 21

In recent years, the development of information and digitalization is growing very rapidly, especially in the state of distance learning due to the COVID-19 pandemic. In addition, this era leads to the need for 21st-century skills possessed by students to be survived amid several disruptions in various conventional fields. Assignments based on project-based learning have been carried out to the chemistry students at Indonesia University of Education in the Basic Analytical Chemistry course to learn the effect of project based learning using youtube as the publication media to improve various 21st-century skills. 6 videos explained the advanced methods applied in the analytical chemistry field have been resulted in. These videos were uploaded to YouTube with a total of 2662 viewers, 1577 likes, as well as 235 comments. Descriptive studies were used as a research method to get some respon from students according to the implementation of 21st-century skills. In addition, we collected qualitative respons from viewers related to the content of explanatory videos that have been made. Through a survey, around 85% of students stated agree and strongly agree that this project-based learning could improve their collaboration skill (4.34/5 scale), scientific literature literacy (4.40/5), creative thinking (4,49/5), communication (4.54/5) as well as critical thinking (4.7/5). Finally, positive and supportive respon from audiences strengthened arguments that this assignment could be exercising the teaching and communication skills of students

Peningkatan Kompetensi Profesional MGMP Kimia Kabupaten Pasaman Sebagai Pembina Siswa Menghadapi Olimpiade Sains Nasional (OSN)

IMPROVİNG THE PROFESSİONAL COMPETENCE OF MGMP CHEMİSTRY İN PASAMAN REGENCY AS STUDENT COACHES FACİNG THE NATİONAL SCİENCE OLYMPİAD (OSN). Teacher training for National Science Olympiad (OSN) coaches is carried out as an effort to improve the professional competence of the Pasaman Regency Chemistry MGMP to prepare students to take part in competitions at the district and provincial levels. The ability of teachers prior to participating in the training was identified using pre-tests originating from OSN questions for the last five years. The training was carried out through analysis of OSN-K (City/District Level) and OSN-P (Provincial Level) questions for the last 5 years in 5 groups, and each group made written discussions which were compiled into modules that could be used by the trainees to prepare students in their respective schools. After that, discussions on HOTS questions in the fields of Inorganic Chemistry, Organic Chemistry, Physical Chemistry, Analytical Chemistry and Biochemistry were given by the resource persons. At the end of the activity, a final test is given to see the effectiveness of the training. The results of the pre-test and post-test showed an increase in participants' understanding of 23.51. In addition, the response to the activity evaluation questionnaire obtained an average questionnaire of 3.47 (scale 4), which means that the training is in the good category.

In situ synthesis of low-cost NELIBS substrate for rapid detection of ultra-low trace elements in liquid samples

Nanoparticle Enhanced LIBS is one of the most powerful and emerging techniques with high sensitivity for trace element analysis and finding increasing applications in various fields of analytical chemistry. Despite many efforts being put forward for the design of NELIBS substrate, it remains a great challenge for developing a highly sensitive substrate that could be helpful for environmental and biological applications. In this work, we report our attempt to improve the detection sensitivity by developing a facile and versatile method capable of generating silver nanoparticles in-situ on the surface of poly dimethyl siloxane (PDMS) in a simple, cost-effective, and additional capping agent free-way. The prepared Ag-decorated PDMS substrate exhibits excellent sensitivity at extremely low concentrations enabling the detection of Cu, Pb, and Cd at a concentration as low as sub ppb levels. Analytical prediction capabilities of this technique was validated using leave one out method and results show interesting possibilities.

Investigation of the applicability of silica-graphene hybrid materials as stationary phases for capillary liquid chromatography

Graphene and graphene-derived substances are cutting-edge materials receiving increasing attention in the analytical chemistry field. Graphene oxide sheets bonded to amino silica particles functionalized with octadecyl (C18) groups and endcapped, also known as SiGO-C18ec, have been successfully employed as extraction phases and in analytical columns associated with conventional liquid chromatography (LC). In this work, SiGO-C18ec particles of 3, 5, and 10 µm nominal id were employed to pack capillary LC columns (100 mm long x 0.3 mm id), and their performance in the gradient mode was evaluated and compared. A 3 µm C18 capillary LC column (50 x 0.3 mm) was used as a reference column. Eight analytes having different polarities and topological surface areas were selected as a probe in this study: carbofuran clomazone, hexazinone, carbamazepine, citalopram, clomipramine, desipramine, and ochratoxin A. Studies about orthogonality were performed to investigate the orthogonality between the SiGO-C18ec and C18 phases. Among the SiGO-C18ec phases investigated, the column packed with 5 µm SiGO-C18ec particles presented the best peak capacity (29) in 15 min.Additionally, the performance of the columns packed with 5 µm SiGO-C18ec particles overcame the performance of the C18 columns used. Significant orthogonality was found between C18 and SiGO-C18ec packed columns; however, no significant differences were found between columns packed with SiGO-C18ec particles of different diameters.