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.

Sequential Injection System for Analysis of Degree Brix, Orthophosphate and pH in Raw Sugarcane Juice Applicable to Sugar Industry

This work presents, for the first time, a new sequential injection analysis (SIA) method to simultaneously analyze degree Brix, orthophosphate and pH in raw cane juice. These key parameters relate to price of harvested sugarcane and quality of cane juice for sugar production. The SIA system employed two detectors: the first detector is a diode-array spectrophotometer, equipped with a regular flow cell, for measurements of degree Brix and orthophosphate. Quantitative of degree Brix (°Bx; ca. % (w/w) sucrose) was based on manipulation of the schlieren effect at the interface between plugs of sample and water. Orthophosphate analysis was carried out based on the molybdenum blue method with significant reduction in consumption of the reagents. Compensation of the schlieren effect from sucrose for determination of orthophosphate was achieved by using a dual-wavelength spectrometric detection. Second detector is a pH-sensing device, called ion-selective field-effect transistors (ISFET). The ISFET is based on the current through the ISFET arising according to the H+ concentration in solution. Our developed SIA system provides linear calibration graphs fitting for purpose in analysis of sugarcane juice (pH: 0–14, °Bx: 1.0–7.0 and P2O5: 20–200 mg L−1). Simultaneous analysis of sugarcane juice for pH, °Bx and P2O5 is carried out within 5 min (12 sample per h). Precision of SIA system is acceptable (RSD < 3%). Our SIA system gave quantitative results insignificantly different, as compared with conventional methods for analysis of pH, °Bx and P2O5 in sugarcane juice.

Sequential Injection Analysis for Automation and Evaluation of Drug Liberation Profiles: Clotrimazole Liberation Monitoring

A fully automated sequential injection system was tested in terms of its application in liberation testing, and capabilities and limitations were discussed for clotrimazole liberation from three semisolid formulations. An evaluation based on kinetic profiles obtained in short and longer sampling intervals and steady-state flux values were applied as traditional methods. The obtained clotrimazole liberation profile was faster in the case of Delcore and slower for Clotrimazol AL and Canesten cream commercial formulations. The steady-state flux values for the tested formulations were 52 µg cm−2 h−1 for Canesten, 35 µg cm−2 h−1 for Clotrimazol AL, and 7.2 µg cm−2 h−1 for Delcore measured in 4 min sampling intervals. A simplified approach for the evaluation of the initial rate based on the gradient between the second and third sampling points was used for the first time and was found to correspond well with the results of the conventional methods. A comparison based on the ratio of the steady-state flux and the initial rate values for Canesten and Clotrimazol AL proved the similarity of the obtained results. The proposed alternative was successfully implemented for the comparison of short-term kinetic profiles. Consequently, a faster and simpler approach for dissolution/liberation testing can be used.

Sequential electrodeposition of Cu–Pt bimetallic nanocatalysts on boron-doped diamond electrodes for the simple and rapid detection of methanol

In this work, a novel electrochemical sensor for methanol determination was established by developing a bimetallic catalyst with superiority to a monometallic catalyst. A Cu–Pt nanocatalyst was proposed and easily synthesized by sequential electrodeposition onto a boron-doped diamond (BDD) electrode. The successful deposition of this nanocatalyst was then verified by scanning electron microscopy and energy dispersive spectroscopy. The electrodeposition technique and sequence of metal deposition significantly affected the surface morphology and electrocatalytic properties of the Cu–Pt nanocatalyst. The presence of Cu atoms reduced the adsorption of other species on the Pt surface, consequently enhancing the long-term stability and poisoning tolerance of Pt nanocatalysts during the methanol oxidation process. This advanced sensor was also integrated with sequential injection analysis to achieve automated and high-throughput analysis. This combination can significantly improve the detection limit of the developed sensor by approximately 100 times compared with that of the cyclic voltammetric technique. The limit of detection of this sensor was 83 µM (S/N = 3), and wide linearity of the standard curve for methanol concentrations ranging from 0.1 to 1000 mM was achieved. Finally, this proposed sensor was successfully applied to detect methanol in fruit and vegetable beverage samples.

Recently Developed Adsorbing Materials for Fluoride Removal from Water and Fluoride Analytical Determination Techniques: A Review

In recent years, there has been an increase in public perception of the detrimental side-effects of fluoride to human health due to its effects on teeth and bones. Today, there is a plethora of techniques available for the removal of fluoride from drinking water. Among them, adsorption is a very prospective method because of its handy operation, cost efficiency, and high selectivity. Along with efforts to assist fluoride removal from drinking waters, extensive attention has been also paid to the accurate measurement of fluoride in water. Currently, the analytical methods that are used for fluoride determination can be classified into chromatographic methods (e.g., ionic chromatography), electrochemical methods (e.g., voltammetry, potentiometry, and polarography), spectroscopic methods (e.g., molecular absorption spectrometry), microfluidic analysis (e.g., flow injection analysis and sequential injection analysis), titration, and sensors. In this review article, we discuss the available techniques and the ongoing effort for achieving enhanced fluoride removal by applying novel adsorbents such as carbon-based materials (i.e., activated carbon, graphene oxide, and carbon nanotubes) and nanostructured materials, combining metals and their oxides or hydroxides as well as natural materials. Emphasis has been given to the use of lanthanum (La) in the modification of materials, both activated carbon and hybrid materials (i.e., La/Mg/Si-AC, La/MA, LaFeO3 NPs), and in the use of MgO nanostructures, which are found to exhibit an adsorption capacity of up to 29,131 mg g−1. The existing analytical methodologies and the current trends in analytical chemistry for fluoride determination in drinking water are also discussed.

LabVIEW virtual instrument for zone penetration studies in flow-based analytical systems

In the flow method development, zone penetration studies are usually conducted as a part of initial screening phase. A lack of an appropriate tool can keep these studies on the level of rough estimations. The developed LabVIEW virtual instrument (VI) which processes peak signals and calculates the overlapping area and fundamental peak-related parameters was used for calculations in experiments that are modelling sample and reagent plug interaction within liquid conduits. The reliability of the predictions was initially confirmed on the artificial data set based on thirty-six files covering all the different types of cases that can be foreseen. In the continuation, volumes of model solutions, propelling flow rate, and coil length in the sequential injection analysis system, were varied by following Box-Behnken response surface design. In three examples, it is demonstrated how the VI can help us plan further experiments in the range which ensures efficient zone overlapping, economic exploitation of reagent plug and adequate dispersion. The application of the VI is not limited just to flow-based chemistry, it can also be useful in spectroscopy and chromatography. To utilize the graphical user interface, it is not necessary to have the LabVIEW program installed.