Current Analytical Chemistry - Volume 17, Issue 4, 2021

Background: In recent years, the occurrence and fate of environmental pollutants has been recognized as one of the emerging issues in environmental chemistry. A survey documented a wide variety of these pollutants, which are often detected in our environment and these are a major cause of shortened life spans and global warming. These pollutants include toxic metal, pesticides, fertilizers, drugs, and dyes released into the soil and major water bodies. The presence of these contaminants causes major disturbance in the balance of the eco-system. To tackle these issues, many technological improvements are made to detect minute contaminations. The latest issue being answered by scientists is the use of green nanomaterials as sensors which are economical, instant and give much better results at low concentrations and can be used for the field measurements resulting in no dangerous by-product that could lead to more environmental contamination. Nanomaterials are known for their wide bandgap, enhanced physical, and optical properties with the option of tuneability as per need, by optimizing certain parameters. They are proved to be a good choice for analytical/ optical sensors with high sensitivity. Objective: This review holds information about multiple methods that use green nanomaterials for the analytical assessment of environmental pollutants. UV-Vis spectrophotometry and electrochemical analysis using green and reproducible nanomaterials are the major focus of this review article. To date, there are a number of spectrophotometric and electrochemical methods available that have been used for the detection of environmental pollutants such as toxic metals, pesticides, and dyes. Conclusion: The use of nanomaterials can drastically change the detection limits due to having a large surface area, strong catalytic properties, and tunable possibility. With the use of nanomaterials, lower than the marked limit of detection and limit of quantification were seen when compared with previously reported work. The used nanomaterials could be washed, dried, and reused, which makes the methods more proficient, cost-effective, and environmentally friendly.

Background: The protection of the ecology is an important task to control and restore the quality of environmental media through the reduction or prevention of the pollutants. Due to the growing awareness of safety, health and environmental issues, the use of non-toxic, clean and ecofriendly methods in the synthesis of nanoparticles has emerged out of necessity. Methods: In this article, the following concepts were considered: strategies of green chemistry, green chemistry metrics, waste management, green nanotechnology/nanoscience and characterization. Furthermore, the tables that include the covered topics were also presented in the manuscript. Results: The green synthesis of nanomaterials is a safe, energy-efficient and fast method which reduces the use of solvents, reagents, and preservatives that are hazardous to environment and human health. Conclusion: The fabrication of nanomaterials with green methods is a clean, safe, nontoxic and environmentally- friendly application which is necessary especially in large-scale operations.

Background: Polycyclic aromatic hydrocarbons (PAHs) are common environmental contaminants consisting of two or more fused benzene rings. PAHs can be introduced into foodstuffs through different ways, such as smoking, roasting and grilling for meat and fish, absorption from the environment for edible oils, chemical treatment of crops for plant-based products, or contamination through packaging during storage. Due to the low concentrations of PAHs in foodstuffs, a clean-up and preconcentration sample preparation technique is of high importance. Until recently, solid-phase and liquid-liquid extraction were the most popular sample preparation techniques for the extraction of PAHs from food matrices. However, due to the fundamental drawbacks of those extraction procedures, a plethora of novel methods, including micro-extraction techniques and miniaturized extraction techniques, have been developed. Moreover, a wide variety of novel adsorbent materials (e.g., metal-organic frameworks, carbon-based materials, etc.) have been synthesized and applied for PAHs’ extraction. Objective: This review aims to discuss recent advances in the extraction techniques of PAHs from food samples, utilizing novel sample preparation approaches and adsorbents. Conclusion: Compared with the traditional sample preparation techniques, the herein discussed green miniaturized extraction and microextraction techniques offer multiple benefits, including simplicity, reduced sample preparation time, as well as reduced consumption of organic solvents.

Background: Bisphenols are major industrial chemicals that have raised public concern due to their endocrine disrupting properties and toxicity. Sample preparation is the most critical step for the determination of bisphenols, especially if the analyst has to deal with environmental samples which are complex matrices and the co-extraction and co-elution of other relevant compounds results in the enhancement or suppression of the analyte signal. The need for the precise determination of bisphenols has signaled the development of effective microextraction techniques according to the Green Analytical Chemistry (GAC) guidelines. Objective: The objective of this review is to gather and discuss all the recent advances in the development of microextraction techniques such as solid phase extraction (SPE), solid phase microextraction (SPME), magnetic solid phase microextraction (MSPE), liquid-phase microextraction (LPME), dispersive liquid-liquid microextraction (DLLME), stir bar sorptive extraction (SBSE), and matrix solid-phase dispersion (MSPD), that have been successfully applied in the extraction of bisphenols from environmental matrices. Conclusion: The analytical performance of the proposed techniques is critically discussed, highlighting the potential and the limitations of each method.

Background: Nuts have been incorporated into guidelines for healthy eating since they contain considerable amounts of antioxidants and their effects are related to health benefits since they contribute to the prevention of nutritional deficiencies. The micronutrient characterization is based mainly on the determination of phenolics, which is the most abundant class of bioactive compounds in nuts. Terpenes constitute another class of bioactive compounds that are present in nuts and show high volatility. The analysis of phenolic compounds and terpenes is a very demanding task that requires optimization of the chromatographic conditions to improve the separation of the components. Moreover, nuts are rich in unsaturated fatty acids and they are therefore considered as cardioprotective. Gas chromatography is the predominant instrumental analytical technique for the determination of derivatized fatty acids and terpenes in food matrices, while high performance liquid chromatography is currently the most popular technique for the determination of phenolic compounds.

Objective: This review summarizes all the recent advances in the optimization of the chromatographic conditions for the determination of phenolic compounds, fatty acids and terpenes in nuts.

Conclusion: The state-of-the art in the technology available is critically discussed, exploring new analytical approaches to reduce the time of analysis and improve the performance of the chromatographic systems in terms of precision, reproducibility, limits of detection and quantification and overall quality of the results.

Background: Conventional analytical methods for phosphorus and sulfur determination in several matrices present normally analytical challenges regarding inaccuracy, detectability and waste generation. Objective: The main objective is proposing a green and feasible analytical method for phosphorus and sulfur determination in animal feed. Methods: Synergic effect between microwave and ultraviolet radiations during sample preparation was evaluated for the first time for the animal feed digestion associated with further phosphorus and sulfur determination by ion chromatography with conductivity detection. Dissolved carbon and residual acidity in the final digests were used for the proposed method assessment. Phosphorus and sulfur values were compared with those obtained using conventional microwaveassisted wet digestion in closed vessels associated with inductively coupled plasma optical emission spectrometry and with those obtained using an official method (Association of Official Analytical Chemists International). Recovery tests and certified reference material analyses were performed. Animal feeds were analyzed using the proposed method. Results: Sample masses of 500 mg were efficiently digested using only 2 mol L^-1 HNO3. The results obtained by the proposed method were not differing significantly (p > 0.05) from those obtained by conventional and by official methods. Suitable recoveries (from 94 to 99%), agreement with certified values (101 and 104%), and suitable relative standard deviations (< 8%) were achieved. Phosphorus and sulfur content in commercial products varied in a wide range (P: 5,873 to 28,387 mg kg^-1 and S: 2,165 to 4,501 mg kg^-1). Conclusion: The proposed method is a green, safe, accurate, precise and sensitive alternative for animal feed quality control.

Background: Lithocarpus litseifolius (Hance) Chun (L. litseifolius) has been used for treating diabetes, allergic and inflammatory diseases, and hyperlipidemia in folk medicine. Previous studies have shown that the main active ingredients of its leaves are flavonoids. However, to the best of our knowledge, the stem of L. litseifolius has not been investigated for its constituents yet. The stems of the decaying plants fall every year. It is considered as a waste due to limited knowledge of the benefits of these stems, which is a sheer waste of the plant resource. Therefore, it is necessary to investigate the chemical constituents of the stem, which will be beneficial for the treatment of many diseases and help utilize the stem in a better way instead of wasting the plant resource. Methods: In this study, the dry twigs of L. litseifolius were collected, powdered, and extracted. Then, the extracted sample was subjected to UHPLC-Q-Exactive Orbitrap MS in negative mode combined with Parallel reaction monitoring scanning to gain the high-resolution mass spectrum, which was processed by the Compound Discover version 3.0 using high resolution extracted ion chromatography to predict the constituent compounds. Results: A total of 35 flavonoids including flavone, flavonol, dihydroflavone, isoflavone, and dihydrochalcone were putatively identified based on their accurate mass measurement, chromatographic retention, MSn spectra, and bibliography data. Conclusion: In this study, a total of 35 flavonoids were identified in the stem of L. litseifolius, among which 5 flavonoids were the first to be reported from this plant, which will be very helpful for the development of medicines for the treatment of many diseases and utilization of the stem of L. litseifolius.

Background: Ocimum basilicum L. seeds, is commonly also known as Takhmaria in Gujarat. It is a common constituent present in fruits, plant-derived beverages, vegetables, wheat, sprouts, and some seasonings. Objective: A simple, specific, precise, accurate, and sensitive method for the quantification of apigenin by reverse-phase high-performance liquid chromatography (RP-HPLC) was developed and validated. Methods: Analysis was carried out on Inertsil ODS-3V-C18 column (250 mm × 4.6 mm i.d, 5 μm) as stationary phase and methanol-acetonitrile (55:45 v/v) as a mobile phase at a flow rate of 1.0 mL/ min. Detection was carried out at 340 nm. The retention time of apigenin was found to be 8.30 min. The proposed method was validated according to ICH Guidelines, Q2 (R1). Results: The developed method showed good linearity in the range of 10-50 μg/mL with a correlation coefficient (R2= 0.9998). The LOD and LOQ were found to be 1.23 μg/mL and 4.05 μg/mL, respectively. The percentage recovery for apigenin was found to be 97.75-100.5%. All validation parameters were found within acceptable limits and demonstrated good reliability in the quantification of apigenin. Conclusion: Thus, the newly developed and validated method can be successfully applied for the quantification of apigenin from seeds of O. basilicum L. and can also be applied for the standardization of polyherbal formulation containing O. basilicum seeds. Assay results showed good recovery when statistically compared with the high-performance thin-layer chromatography (HPTLC) method.

Background: The possibility of estimating the age of fossil bones using only classic thermogravimetry, on the basis of proper % mass loss ratio values, has been widely considered in the past years. Objective: Our research has brought some innovations to the previous background, by using chemometric methods and by processing the numerical files of whole thermogravimetric curves. The objective of this paper is the selection, among the main thermal analysis methods available, i.e., thermogravimetry (TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA) and thermal dilatometry analysis (TDA), of the most suitable one, in order to evaluate the age of fossil bones. Methods: Fossil bone samples from two ancient cemeteries in Sudan were analyzed using different thermal methods (TG, DTG, DTA, and TDA). Data of whole recorded thermal curves have been processed by PCA analysis. Results: A systematic comparison of several thermal analytical techniques allowed to conclude that TG or DTG curves can provide more appropriate information to determine how old fossil bones of different ages are, as evidenced by PCA processing of the entire file set of TG or DTG curves. Conclusion: It can be concluded that the chemometric processing of TG or DTG curves data files is the best method; however, discussing other thermal analytical curves (DTA and TDA) can complete the information found by means of chemometric processing of whole TG and DTG curves.

Background: Hydrogen peroxide (H2O2) is widely used in various fields and it plays a quintessential role in a variety of biomolecular processes. H2O2 concentration level is an essential biological parameter in monitoring and maintaining the physiological balance of a living cell, and its variation causes some related diseases. Therefore, it is extremely significant to fabricate biosensor with low cost, which can quickly, accurately and sensitively detect H2O2 in a wide range. The aims of this paper are to explore a novel electrochemical sensor with high intrinsic peroxidase-like activity, high sensitivity and stability to effectively detect H2O2 concentration in real samples. Methods: The chemically modified electrode LaNiTiO3-Fe3O4/GCE was fabricated based on the nanomaterial LaNiTiO3-Fe3O4 by a simple process, and its electrochemical properties were investigated in the supporting electrolyte of 0.1 M NaOH by the techniques of cyclic voltammetry and currenttime curves on an electrochemical workstation with a conventional three-electrode system. Results: LaNiTiO3-Fe3O4 nanoparticles show good peroxidase-like activity for H2O2 at a low applied potential of +0.50 V. Under the optimum conditions, the peroxidase biomimetic sensor LaNiTiO3-Fe3O4/GCE exhibited a wide linear response for H2O2 oxidation in the range of 0.05 μM - 3.0 mM (R = 0.9994) with a high sensitivity of 3946.2 μA·mM-1·cm-2 and fast response time of 2 s; besides, the detection limit of H2O2 was found to be ca. 5.15 nM (S/N = 3). Moreover, the biosensor exhibited good repeatability, stability and anti-interference. Satisfactory results were obtained when the sensor LaNiTiO3-Fe3O4/GCE was applied to determine H2O2 in real samples. All of these results provide support to practical application. Conclusion: A highly sensitive peroxidase biomimetic sensor based on LaNiTiO3-Fe3O4 with nanoscaled material has been successfully explored, and shows good activity for H2O2. The proposed biosensor with simple and low cost exhibited excellent advantages of quick response, wide linear range, low detection limit, high sensitivity, long-term stability and good anti-interference ability, which offer promising applications.

Background: Platinum (Pt), palladium (Pd), rhodium (Rh) and iridium (Ir) are platinum group elements (PGEs) and also important elements of geochemistry and environmental chemistry with the similar physic-chemical properties, which have been widely used in industry and laboratory. However, due to the low abundance and inhomogeneous distribution in natural ore as well as the nugget effect, the accurate determination of PGEs has been a challenge to analytical chemistry. Methods: In this work, a novel fire assay method was reported for the determination of ultra-trace Pt, Pd, Rh and Ir in geochemical samples. Tin powder (Sn) instead of stannic oxide (SnO2) was used as a fire assay collector to reduce the melting temperature from 1250°C to 1050°C, the escape of molten material caused by high temperature was successfully avoided. Tin bead was compressed into thin slice and dissolved by HCl. For the target Pt, Pd, Rh and Ir, HCl insoluble substance such as PtSn4, PdSn4, RhSn4 and Ir3Sn7 were formed and separated from matrix by filtering. The metal compounds precipitate together with filter paper were microwave-assisted completely digested by aqua regia (50%, v/v), thence the sample solution was determined by inductively coupled plasma mass spectrometry (ICP-MS). Results: Compared with nickel oxide and lead oxide in nickel sulfide /lead fire assay, the reagent blank of tin powder were relatively low and could be directly employed in tin fire assay to collect Pt, Pd, Rh and Ir without purifying. Moreover, the harm of nickel oxide and lead oxide to the analyst and environment was avoided by using the non-toxic tin powder. The decomposition method of chromite and black shale was investigated as well as the amount of tin powder and flour, microwave digestion program for the determination of Pt, Pd, Rh and Ir were optimized. Besides, the influence of mass spectrum interference of co-existing elements was discussed and the standard mode and kinetic energy discrimination collision pool mode were compared. Under the optimal conditions, excellent curve fitting of Pt, Pd, Rh and Ir were obtained between 0.01~100 ng mL^-1, with the correlation coefficients exceeding 0.9996. The detection limits were from 0.003 ng g^-1 to 0.057 ng g^-1. Conclusion: The developed method was applied to analyze the Chinese Certified Reference Materials and the determined values were in good agreement with the certified values.

Background: It is demonstrated that for a junior research faculty in India, proper guidelines and funding resources are required to publish research articles in the Open Access (OA) journals. Recently, many of the important scientific journals are turned out to be OA journals. When we need to publish in an OA journal, the funding support for article processing charge (APC) is uncertain due to the limited funds or absence of institutional level support. Objective: To find out the total number of open access and subscription based articles published from the top ten countries in the scientific journals up to July 2020. Materials and Methods: For the data collection, a keyword of “Chemistry” was used in all fields in the “Scopus database” on 07 July 2020. Results: From the articles published by top ten countries, it was found that USA has published more number of publications (open access plus subscription based) followed by China, Japan, Germany, UK, India, France, Canada, Italy, and the Russian Federation. However, if we carefully look at the total numbers of OA publications up to July 2020, Japan (33.47%) has published more percentage of OA documents compared to UK (26.92%), Germany (24.63%) and the USA (24.53%). In this list, India (13.02%) and the Russian Federation (10.14%) have published the lowest numbers of OA publications compared to other countries. Conclusion: It was found that about ~50% of OA publications resulted from India might come from collaborative research. The APC may be supported by other countries along with India. In addition, it was obvious that the Indian Institute of Science (IISC) had published the highest OA papers, followed by CSIR India and the University of Delhi. From the past ten years, OA publications from India were doubled in number from 2011 to July 2020. However, it requires further efforts to increase our scientific progress and research accomplishments by the number of publications, patents, and commercial products to support the Make in India.