BrJAC mourns the death of Prof. Dr. Miguel Valcárcel Cases and recognizes his great contribution to Analytical Chemistry and Science around the World

Who has not seen or heard about books such as Analytical Chemistry: A Modern Approach to Analytical Science, Principles of Analytical Chemistry: A Textbook, or Foundations of Analytical Chemistry: A Teaching-Learning Approach, or about flow injection analysis-FIA, and sequential injection analysis-SIA? These are, in fact, some contributions from Prof. Miguel Valcárcel Cases, at the University of Córdoba-Spain, who leave us on 9th January 2022 at the age of 75. Prof. Valcárcel was Dean of the Faculty of Sciences at the University of Córdoba, Vice-Rector for academic guidance and teaching and Vice-Rector for quality, as well as the first Director of the Andalusian Institute of Fine Chemistry and Nanochemistry since 1994. Born in Barcelona (Spain), Prof. Valcárcel was a graduate of the University of Seville where also obtained his Ph.D., and was an assistant teacher until 1975. He was an associate professor of Analytical Chemistry at the Faculty of Science of Palma de Mallorca in 1975, an institution where he was also Dean and full professor at the University of Cordoba in the year 1976. He was also President of the Analytical Division of the European Federation of Chemical Societies and was a member for 4 years of the High-Level Expert Group of the European Union's Growth Program. Valcárcel received the Spanish national Enrique Moles prize for Chemical Science and Technology (2005), the Maimónides prize for scientific-technical research from the Junta de Andalucia (1992), and the Solvay Research Prize in Chemical Sciences from the CEOE Foundation (1997). He has the Robert Boyle Medal from the Royal Society of Chemistry (UK, 2004), the Enrich Planquette Prize from the Austrian Chemical Society (1996), the Gold Medal from the University of Warsaw (2000), and the Medal from the Portuguese Chemical Society (2000). He also received the distinction of Cordoba citizen of the year 2006 in the education/research section, and the Averroes de Oro-Cuidad de Córdoba medal in 2006 for his scientific trajectory. He was also awarded the title of Doctor Honoris Causa by the University of Valencia (2010) and the European DAC-EuChMS (Division of Analytical Chemistry of the European Association for Chemical and Molecular Sciences) award in recognition of his scientific and teaching career (2015). He was the author of ca. 700 papers, published 9 scientific books, and co-authored 15 chapters of multi-author books. Owner of a unique vitality and a very accurate vision of Analytical Chemistry, Prof. Valcárcel contributed to the formation of dozens of students, of which he was extremely proud, and some of them are today Full professors spread all over the world. The Brazilian Journal of Analytical Chemistry mourns his death, and through this simple tribute, recognizes his great contribution to Analytical Chemistry and science around the world.

Extraction, Characterization and Rheological Behavior of Tamarind Gum Under High Salinity

The objective of this work was to obtain tamarind gum from Tamarindus indica L. seeds, which are waste from the food industry. Tamarind gum was extracted by two methods and the highest yield achieved was 32.6% w/w, containing 69.25% w/w of organic matter, which was composed mostly of the nonionic polysaccharide xyloglucan. The greatest molar mass of the tamarind gum was Mw=7.16 x 105 g/mol with polydispersity index (PI) of 1.7. Evaluation of the rheological behavior of tamarind gum samples were carried out in two brines (total dissolved solids values of 29,711 mg/L and 68,317 mg/L, containing divalent ions) that simulated petroleum reservoir salinity levels, with different temperatures (25, 60 and 80°C). The rheological curves indicated high salt resistance of the gum samples. Under a shear rate of 7.3 s-1 the highest viscosity values found were approximately 86, 41 and 50 cP with at concentration of 5,000 ppm and temperatures of 25, 60 and 80ºC, respectively.

Methodology for Preconcentration and Determination of Silver in Aqueous Samples using Cloud Point Extraction

For the selective extraction of silver, a cloud point extraction (CPE) procedure was developed. After synthesizing the solvation species through the reaction of silver ions with 2, 4-dimethyl pentane-3-one (2,4 DMP), the salting-out agent (0.4 mol L-1 NaNO3) was added at 35 °C and, after 10 min, Triton X-114 was used to separate silver ions from aqueous solution. The type and quantity of salting-out agent, silver ion, temperature, heating time, and surfactant volume were all examined as important factors determining the CPE. The analytical curve in the 0.1-100 μg L-1 Ag range was straight at optimal conditions. The detection limit (LOD), quantification limit (LOQ), and enrichment factor (E) were 0.05 µg L-1, 0.15 µg L-1, and 200, respectively. The relative standard deviation (RSD) was estimated as 0.2-3.9% (n = 5) in relation to 1, 40, and 80 μg L-1 Ag. Flame atomic absorption spectrometry and spectrophotometry exploiting dithizone were used to assess the CPE accuracy. The proposed approach was then applied to river water, rain water and sand samples.

Restricted Access Molecularly Imprinted Polymers for Biological Sample Preparation

Restricted access molecularly imprinted polymers (RAMIPs) have been efficiently used for the extraction of small organic molecules from untreated biological matrices (e.g. blood, plasma, serum, and milk). These materials have been obtained by modifying the external surface of conventional molecularly imprinted polymers (MIPs) with hydrophilic monomer grafting, crosslinked protein capsule or a combination of both. These sorbents aggregate the selectivity of MIPs with the ability to exclude macromolecules of restricted access materials (RAMs), being widely employed in solid phase extraction techniques, beyond their use in sensors. In this review, we discuss about the design and application of RAMIPs in biological sample preparation, emphasizing the future trends and remaining challenges of this technology for bioanalyses.

Determination of the Trace Element Contents of Fruit Juice Samples by ICP OES and ICP-MS

Fruit juices were analysed for their contents in a series of essential and toxic elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, V, Sb, Mo and Zn). Samples were subjected to microwave-assisted acid digestion (HNO3/H2O2), and analytes were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), in axial mode, or by inductively coupled plasma mass spectrometry (ICP-MS), with kinetic energy discrimination, using 103Rh and 89Y as internal standards. The methods were validated, showing good precision (relative standard deviations < 10%), linearity and mean analytical recovery values (89 to 103%). The ICP-OES instrumental limits of detection (LODs) were between 0.3 μg L-1 (for Mg) and 1.5 μg L-1 (for Ca), whereas ICP-MS instrumental LODs varied from 2 ng L-1 (for Co, Mo and V) to 5.7 μg L-1 (for Na). Some toxic elements (As and Sb) were not detected in the fruit juices analyzed, Cd concentrations were below the maximum permitted level established by Brazilian and European regulations and only in one sample the Pb concentration (61.7 µg L-1) exceeded current legal limits. Besides, essential elements such as Ca, Mg and Na were in high concentrations in the samples analyzed.

The applicability of solid state characterization and analytical techniques for reference chemical substance certification: Resolution of the Collegiate Board (RDC) 166/2017 by National Health Surveillance Agency (ANVISA)

Reference chemical substances called primary reference are used which are marketed by official compendia both nationally and internationally in the pharmaceutical industry as a tool for identification and quantification during pre-formulation, development/analytical validation and quality control studies. The reference or primary standards are almost always imported and resold in the Brazilian market as a consequence, increasing the cost in relation to the sample amount (little amount of mass in mg per bottle). On July 24, 2017, the National Health Surveillance Agency (ANVISA) published the Resolution of the Collegiate Board (RDC) number 166, which deals with the validation of analytical methods. The Chapter III of this resolution is intended for reference chemical substances and, in Art. 14 § 1, the RDC 166/2017 allows the use of characterized reference chemical substances in the analytical validations. The characterization study is planned according to the chemical structure of the substance to be characterized and within this new regulation, solid-state characterization and analytical chemistry stands out as an essential ally corroborating with the evolution of the number of publications in the literature regarding this subject in the google scholar database as shown in Figures 1 and 2.

HO- and OH-, Reason and Tradition

Writing OH- is so widespread that one hardly notices that there no logical reason, apart from being accustomed to so, not to write HO- instead. Scientists should be educated to spot irregularities, since often they mean something. Chemistry professors, in particularly at graduate level, when teaching pH, should make their students notice such discrepancy. Albeit pH is not a complex topic it is intriguing the number of misconceptions, and even plain errors, associated. For example, the limits of the pH scale, it is not uncommon to find students (and not just undergrads) believing pH values cannot be lower than 1 or higher than 14, or that negative pH values do not exist. Herein, it is addressed the odd exception of writing OH- instead of the most logical form of HO-. It is fascinating that chemists are so accustomed to see OH- that they do not longer find it to be an oddity. First, it is important to highlight why it is a nomenclature exception, i.e., the lack of reason to write OH-.

Quo vadis Spectroscopy?

Since the early days of modern chemistry, analytical chemistry always tried to offer solutions to real-life problems. This is how, in the midst of the Industrial Revolution, Margueritte developed the titrimetric determination of iron using the chameleon solution (potassium permanganate). In 1860, for the first time, Bunsen and Kirchhoff used element-specific light emission and absorption of flame-evaporated alkali metal salts for qualitative analysis. Their discovery was groundbreaking because the analytical sensitivity and detection capability of the proposed method was several orders of magnitude lower than that of the contemporary classical analytical ones. Application of this method, leading to the establishment of spectroscopic techniques, also allowed the discovery of about ten chemical elements. Another timeless merit of spectroscopy is the ability to determine the elemental composition of a star in a distant galaxy. In the second half of the 20th century, an era of rapid development of instrumental analysis, atomic spectroscopy also brought several revolutionary results. One such breakthrough was the reduction of the sample volume required for analysis down to microliters with the introduction of graphite furnace atomic absorption spectrometry (GFAAS). The detection limit of GFAAS also decreased by several orders of magnitude. Another important advance was the combination of inductively coupled plasma as a high-temperature ion source with a mass spectrometer (ICP-MS). In the late 1980s, the hyphenation of atomic spectrometric devices to chromatographs, aiming at elemental speciation, also emerged. In Central and Eastern Europe, spectroscopic research was driven by the embargo of the Coordinating Committee for Multilateral Export Controls established by the Western Bloc during the Cold War. In this emerging era, scientific research and applications went hand in hand. Therefore, the science education program and fundamental research were very strong in those countries, contributing considerably to the development of spectrochemistry in Hungary. By the end of the 20th century, development of new equipment and procedures was increasingly carried out by instrument manufacturers, and fundamental research at universities and institutes was relegated to second place. Analytical chemistry has experienced a considerable shift from determination of inorganic compounds and small organic molecules towards that of large (bio)molecules. Expansion of the application of analytical chemistry to forensic, environmental and biochemical questions has been observed and the role of atomic spectrometric techniques seemed to fade away. However, sheer use of these high-performance instruments is not always appropriate or cost-effective; the reliability of the results and elimination of interference must be thoroughly explored. However, when publishing such results, there is a risk that our communications will be rejected due to lack of novelty. Nevertheless, carrying out fundamental research cannot be avoided, as it is not possible to offer appropriate decisions to stakeholders based on questionable results. Presently, GFAAS and ICP-MS allow reliable quantitative determination of virtually any element in any sample. Recently, microwave plasma using nitrogen isolated from the air was launched on the market. This device requires significantly lower operating costs compared to the conventional ICP and reliable simultaneous multi-element analysis has also become possible. Another promising direction is single-particle ICP-MS applied for the characterization of inorganic nanoparticles. Most of the articles of the current issue of BrJAC also demonstrate that atomic spectrometry has become indispensable in many areas of our life. Enjoy reading the current issue!

Prof. Santelli, a Tireless Researcher and a Gold-Standard Professor in Analytical Chemistry, kindly spoke to BrJAC

Prof. Dr. Ricardo Erthal Santelli has a degree in Pharmacy from the Federal Fluminense University, Niterói, RJ, BR (1972), a master's degree in Inorganic Analytical Chemistry from the Pontifical Catholic University, Rio de Janeiro, RJ, BR (1978), a doctorate in Inorganic Analytical Chemistry from the same institution (1985), and a postdoctoral degree from the University of Córdoba, Spain (1988). He was a full professor of Environmental Geochemistry at the Federal Fluminense University from 1994 until 2010 when he retired. He is currently Full Professor at the Institute of Chemistry at the Federal University of Rio de Janeiro, BR. He works mainly with the development of spectrometric and chromatographic methods, continuous flow injection analysis, and speciation analysis. He develops research mainly on automation in analytical chemistry, environmental geochemistry, and analytical techniques applied to environmental problems. Prof. Santelli has more than 140 scientific articles published in international journals, with more than 5800 citations and an H-index of 32 in addition to several chapters in international books. He has supervised more than 30 master’s and 15 doctoral students. In the editorial field, Prof. Santelli is currently a member of the Editorial Board of the Brazilian Journal of Analytical Chemistry.

Analytical Challenges for Identification of New Psychoactive Substances: A Literature-Based Study for Seized Drugs

Correct identification of substances is essential to understand drug use and trafficking trends and guide measures for harm reduction and treatment. Two steps are needed to verify the nature of a substance properly: a presumptive test and a confirmatory test. There are presumptive tests which presents deficiencies, such as providing false-positive and false-negative results. Confirmatory tests are more reliable, but they are more expensive. With the appearance of New Psychoactive Substances (NPS), identifying and characterizing illicit substances has become more challenging. This paper focuses on presenting information about NPS characteristics and analysis. For this purpose, we have reviewed the literature to address the main aspects of five groups of NPS: amphetamine-type stimulants, synthetic cannabinoids, N-methoxybenzyl-methoxyphenylethylamine (NBOMe), synthetic opioids, and benzodiazepines. We present the main characteristics of each group and certain aspects of presumptive and confirmatory tests regarding these groups. Our findings show obstacles in developing methodologies that can correctly identify these substances, and problems can increase as new structures appear. This information can be helpful to drive research into identifying NPS and inform law enforcement and law practitioners about the main characteristics of each group and the main questions involving their identification.