Current Analytical Chemistry - Volume 17, Issue 9, 2021

Nanomaterials, owing to their progressive development, could be widely used in electrochemical drug analysis due to their unique physical and chemical properties. Herein, we have presented a general perspective on electrochemical approaches based on different nanomaterials for drug analysis, that were performed in the last decade.

Background: Metabolomics has gained importance in clinical applications over the last decade. Metabolomics studies are significant because the systemic metabolome is directly affected by disease conditions. Metabolome-based biomarkers are actively being developed for early diagnosis and to indicate the stage of specific diseases. Additionally, understanding the effect of an intervention on a living organism at the molecular level is a crucial strategy for understanding novel or unexpected biological processes. Results: The simultaneous improvements in advanced analytical techniques, sample preparation techniques, computer technology, and databank contents have enabled more valuable scientific information to be gained from metabolomics than ever before. With over 15,000 known endogenous metabolites, there is no single analytical technique capable of analyzing the whole metabolome. However, capillary electrophoresis-mass spectrometry (CE-MS) is a unique technique used to analyze an important portion of metabolites not accessible by liquid chromatography or gas chromatography techniques. The analytical capability of CE, combined with recent sample preparation techniques focused on extracting polar-ionic compounds, makes CE-MS a perfect technique for metabolomic studies. Conclusion: Here, previous reviews of CE-MS based metabolomics are evaluated to highlight recent improvements in this technique. Specifically, we review papers from the last two years (2018 and 2019) on CE-MS based metabolomics. The current situation and the challenges faced by metabolomic studies are discussed to reveal the high potential of CE-MS.

Background: In this review, an outline of the development of omics studies in recent years was envisaged. The bottom-up and top-down approaches on system biology were discussed and some of the recent tools that integrate multiomics data on system biology studies were examined. The improvements in omics applications from genomics to metabolomics were inspected in the light of breast cancer biomarker discovery. Results: It is known that genome or proteome analysis alone is not sufficient to elucidate the molecular mechanism of any disease, but instead, a holistic evaluation, including metabolomics studies, is rational and gives definite results. Breast cancer markers approved at the beginning of the millennium encouraged researchers to search for diagnostic and prognostic biomarkers with the improvements of advanced analytical strategies. Obviously, the recent developments on omics techniques and tools to process multiomics data are capable of presenting valuable scientific information better than ever before. Conclusion: Clinical researches using omics techniques might be supported with the integration of multiomics data to validate the results and to understand the molecular interactions in the biological system.

Background: Chromatographic techniques, such as TLC basically and HPLC, GC, HPTLC, equipped with various detectors are most frequently used for the qualitative and quantitative examination of herbals. Methods: An overview of the recent literature concerning the usage of HPTLC for the analysis of medicinal plants has been carried out. Results: During the last decade/s, HPTLC, a modern, sophisticated, and automatized TLC technique with better and advanced separation efficiency, detection limit, data acquisition, and processing, has been used for the analysis of herbal materials and preparations since the rapid development of technology in chromatography world. HPTLC with various detectors is a powerful analytical tool, especially for the phytochemical applications, such as herbal drug quantification and fingerprint analysis. Conclusion: In this review, a latest perspective has been established and some of the previous studies were summarized for the usage of HPTLC in the analysis of herbal remedies, dietary supplements, and nutraceuticals.

Background: Green Chemistry has emerged as a new field of study in chemistry in the past 15 years and is intended to be sustainable at the molecular level. Green Chemistry has focused on harmless chemical technologies to meet both environment and targets. The purpose of Green Chromatography is to protect the environment and the analyst like Green Chemistry. Objective: The main target is to reduce the consumption of hazardous solvent and to replacement of toxic and environmentally hazardous solvents with more benign alternatives. Methods: In addition, reducing the flow rate (decrease column interdiameter, etc.) in order to miniaturizing the waste generation is also within the field of green chromatography. On the other hand, the most effective technique for the “Green” approach can be miniaturized completely. Flow rate decreases from mL to microliter per minute. Thus, waste production and solvent consumption are significantly reduced. Recently, studies without organic solvents such as SFC, SBWC are frequently encountered. Results: Chromatographic analysis has the potential to become greener at all stages, from sample collection and preparation to separation and final determination. Liquid chromatography is often used in pharmaceutical analysis. Tons of wastes are produced every year for pharmaceutical analysis. For this reason, the greening approach in liquid chromatography becomes very important for human and environmental health in pharmaceutical analysis. Conclusion: This review discusses the approaches used to achieve the goals of green chromatography, aimed at protecting the environment and the analyst in pharmaceutical analysis. While one cannot completely convert the analysis to the green, the steps taken to green are very valuable, particularly in wide range used HPLC both in drug quality control laboratories in industry and in research studies.

Background: Quinolones are an important group of synthetic antibiotics with bactericidal action. The antibacterial activity of these compounds has been shown to result from selective inhibition of bacterial DNA synthesis. It is a preferable option in clinical use because of its efficacy, reliability and wide antibacterial spectrum. The identification and quantification of quinolones in various biological tissues and fluids are needed. Methods: Numerous techniques have been developed for their analysis of biological materials and pharmaceutical dosage forms. In this review, the chromatographic methods published in the last ten years for the analysis of quinolones, using for the treatment of an infection in a human, were reviewed. Results: The analysis methods of quinolones as single or simultaneous in biological materials were summarized according to sample preparation, chromatographic conditions, validation parameters and applicability of the methods. The pH effect on the chromatographic behaviors of quinolones was discussed. Moreover, multivariate analysis was performed for the summarized published methods based on the method parameters. Conclusion: Many rapid and efficient separation methods have been developed for individual or simultaneous determination of quinolone. In this study, a comprehensive review is presented for the analysis of quinolone developed in the last decade.

Background: Recently, liquid chromatography based on tandem mass spectrometry (LCMS/ MS) has become an efficient tool in analyzes of many compounds in various biological matrices. However, as known by researchers, these biological matrices cause various interferences by suppressing (ion suppression) or increasing ionization (ion enhancement). Since this challenge was recognized in the 1990s, many studies have been published on it, and its causes have been reviewed countless times for various compounds. However, none of the current studies specifically addressed aspects of matrix effects that have to do with catecholamines. Discussion: This review will focus on these issues, critically discussing experiments and results of matrix effects in LC-MS/MS applications on catecholamine analysis in various biological matrices. Moreover, it can guide the performance of studies on matrix effects in LC-MS/MS procedures in bioanalytical systems. Conclusion: This article is useful for academics such as analytical chemists, pharmacologists and also members of the pharmaceutical industry working on catecholamines and liquid chromatographymass spectrometry.

Background: Electrochemical methods in drug analysis have a lot of advantages, including simplicity, speed, low-cost instrumentation, informing about the drug mechanism, and nonaffection by excipients in dosage forms. Electrochemical techniques utilize the advantages of nanomaterials to increase sensitivity and, in some cases, selectivity. Among these nanomaterials, metal oxide nanoparticles are also preferred by researchers because of their unique properties such as biocompatibility, stability, non-toxicity, and catalytic characteristic. Objective: This review provided brief information about metal oxide nanoparticles used in electrochemical sensors and summarized applications for drug analysis with these sensors in tables showing the studies in the literature during the last decade. Results: In the last decade, metal oxides are frequently used in electrochemical drug analysis as electrode modifier individually and with other nanomaterials especially carbon-based ones. All these studies showed that metal oxide nanoparticles increase the active surface area of the electrode and the catalytic activity. Conclusion: When metal oxide nanoparticles and carbon-based nanomaterials are used together, they create a synergistic effect that further increases catalytic activity and thus lowers detection limits to be obtained in nM even pM levels.

Background: Ionic liquids (ILs) are a unique class of compounds consisting exclusively of cations and anions that possess distinctive properties such as low volatility, high thermal stability, miscibility with water and organic solvents, electrolytic conductivity and non-flammability. Ionic liquids have been defined as "design solvents", because it is possible to modify their physical and chemical properties by appropriately choosing cations and anions, in order to meet the specific characteristics based on their potential application. Introduction: Due of their tunable nature and properties, ILs are considered as the perfect candidates for numerous applications in analytical chemistry including sample preparation, stationary phases in liquid or gas chromatography, additives in capillary electrophoresis, or in mass spectrometry for spectral and electrochemical analysis. In the last years, the number of publications regarding ILs has rapidly increased, highlighting the broad applications of these compounds in various fields of analytical chemistry. Results: This review first described the main physico-chemical characteristics of ionic liquids, and subsequently reported the various applications in different subdisciplines of analytical chemistry, including the extraction procedure and separation techniques. Furthermore, in each paragraph the most recent applications of ionic liquids in the food, environmental, biological, etc. fields have been described. Conclusion: Overall, the topic discussed highlights the key role of ionic liquids in analytical chemistry, giving hints for their future applications in chemistry but also in biology and medicine.

Background: Cephalosporin antibiotics are used to treat bacterial infections in humans and animals. Their excessive usage and massive production rates have led to their presence in the environment, causing serious threats, such as antibiotic resistance. Several methods have been used for the detection and quantification of these antibiotic traces in the environment; among them, sensors have been the most advanced tools that can be very useful for online on-spot detection of these antibiotics. This review briefly discussed electrochemical, colorimetric and biosensors and their use in the detection of trace antibiotics. The provided information gives a brief view of the developed methods that will be helpful in the development of commercially applicable sensing devices for real-time monitoring of antibiotics in the environment. Methods: Research and online content related to the detection of cephalosporin antibiotics were collected. Research methodologies and results were studied and compared. The screening of available data was done by experts, and the most advanced and useful methods were described. A brief introduction to sensing methodologies and the recent advancement in these techniques was reviewed. Results: Different analytical techniques have been used for the detection and quantification of environmental pollutants. Sensors are small-sized devices that have gone through great advancement in recent decades, have leading to highly sensitive and selective tools for trace antibiotic detection. Electrochemical sensors have advantages of high selectivity and robust receptors, while colorimetric sensors provide rapid detection with visible color changes. Biosensors have higher sensitivity and selectivity but are sensitive to environmental changes. There is a great need to develop a simple technique that may combine advantages of all these sensing techniques and can be used in the real world for the screening of antibiotic traces. Conclusion: The recent progress in sensing technology has led to the development of highly sensitive and selective sensors, but they have lab-based applications. We still lack the availability of sensing methodologies that can provide online monitoring of environmental pollutants in the real environment. The recent achievements and inter-disciplinary research have been very fruitful and given hope that we may obtain simple and useful sensing tools for the screening of antibiotic traces in the environment.

Background: The combination of cloud point extraction (CPE) with inductively coupled plasma-optical emission spectrometry (ICP OES) is limited due to the effect of organic diluent and surfactant on the signal. Methods: A dual-CPE process (d-CPE) was presented for the enrichment of aluminum (Al³⁺), before determination by ICP OES, to exclude the effect of surfactant and organic solvent on the ICP OES signal. The analyte was firstly extracted into Triton X-114 rich phase as a gallic acid complex. In the second step, Al³⁺ was back extracted into an aqueous phase of HNO3 that was introduced into ICP OES. The effects of pH, concentrations of gallic acid and Triton X-114, incubation temperature and time, centrifugation conditions and the concomitant ions were evaluated. Results: The method displayed good analytical characteristics at the optimum conditions. An enrichment factor of 49.5 was achieved. The linear calibration graph was obtained from 1.0 to 1000 μg L^-1 and the detection limit was 0.31 μg L^-1. The relative standard deviation was 2.3% (50 μg L^-1 Al³⁺, n = 10). Quantitative recoveries ranging from 96.0 to 100% were obtained for spiked water and geological samples. This procedure was used efficiently for preconcentration and quantification of Al³⁺ in various samples by ICP OES. Conclusion: The presented procedure is simple, rapid, accurate, and safe. It can be used for the determination of Al³⁺ by ICP OES in samples with complicated matrices.

Background: Hydrogen peroxide (H2O2) is a common reagent in the production and living, but excessive H2O2 may enhance the danger to the human body. Consequently, it is very important to develop economical, fast and accurate techniques for detecting H2O2. Methods: A simple two-step electrodeposition process was applied to synthesize Pd-Cu/Cu2O nanocomposite for non-enzymatic H2O2 sensor. Cu/Cu2O nanomaterial was firstly electrodeposited on FTO by potential oscillation technique, and then Pd nanoparticles were electrodeposited on Cu/Cu2O nanomaterial by cyclic voltammetry. The chemical structure, component, and morphology of the synthesized Pd-Cu/Cu2O nanocomposite were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of Pd-Cu/Cu2O nanocomposite were studied by cyclic voltammetry and amperometry. Results: Under optimal conditions, the as-fabricated sensor displayed a broad linear range (5-4000 μM) and low detection limit (1.8 μM) for the determination of H2O2. The proposed sensor showed good selectivity and reproducibility. Meanwhile, the proposed sensor has been successfully applied to detect H2O2 in milk. Conclusion: The Pd-Cu/Cu2O/FTO biosensor exhibits excellent electrochemical activity for H2O2 reduction, which has great potential application in the field of food safety.

We apologize for the error that occurred in the online version of the article. Incorrect name of 5th author was published in the article entitled “Water Pollution Monitoring through Remote Sensing” in “Curr. Anal. Chem., 2021, 17(6), 802-814 [1]. The original article can be found online at https://doi.org/10.2174/1573411016666200206095055 Original: Gadug Sudhamsu Corrected: Gurijala Sudhamsu