Analysing samples in their original form is increasingly crucial in analytical chemistry due to the need for efficient and sustainable practices. Analytical chemists face the dual challenge of achieving accuracy while detecting minute analyte quantities in complex matrices, often requiring sample pretreatment. This necessitates the use of advanced techniques with low detection limits, but the emphasis on sensitivity can conflict with efforts to simplify procedures and reduce solvent use.
View Article and Find Full Text PDFThe enhancement of natural radioactivity in groundwater, specifically in natural mineral water, is related to the lithological formations through which water bodies or courses pass. Although natural mineral waters are exempt from monitoring for radioactive substances according to Council Directive 2013/51/EURATOM, this study focuses on the radiological characterization of natural mineral water under Spanish Royal Decree 3/2023. The water studied was taken from Catalan aquifers with different lithological characteristics (sedimentary, metamorphic or granitic) and is sold on local markets.
View Article and Find Full Text PDFNear-infrared (NIR) spectroscopy is a well-established analytical technique that has been used in many applications over the years. Due to the advancements in the semiconductor industry, NIR instruments have evolved from benchtop instruments to miniaturised portable devices. The miniaturised NIR instruments have gained more interest in recent years because of the fast and robust measurements they provide with almost no sample pretreatments.
View Article and Find Full Text PDFThe primary focus of research in food production revolves around ensuring food quality and safety [...
View Article and Find Full Text PDFSeafood plays an important role in diet because of its health benefits. However, the fact that chemical compounds such as high production volume chemicals may be present in seafood means that its consumption can be a potential risk for population. To assess the occurrence of HPVs and estimate the exposure and risk associated with their consumption, specimens of the most consumed seafood species in Catalonia and the Canary Islands, Spain, were collected and analysed.
View Article and Find Full Text PDFInsects have been a food source for humans for millennia, and they are actively consumed in various parts of the world. This paper aims to ascertain the feasibility of portable near-infrared (NIR) spectroscopy as a reliable and fast candidate for the classification of insect powder samples and the prediction of their major components. Commercially-available insect powder samples were analyzed using two miniaturized NIR instruments.
View Article and Find Full Text PDFSystematic errors in the calix [4] pyrrole-based potentiometric detection of creatinine have been observed in heavy smokers. This work further characterizes the interactions between the nicotinium cation and the cavitand as well as the resulting interference produced during the potentiometric detection. It is found that the nicotinium cation binds the electronic rich aromatic cavity defined by the pyrrole rings of the receptor's cone conformation with an estimated binding constant higher than 10 M in methylene chloride.
View Article and Find Full Text PDFMiniaturized NIR instruments have been increasingly used in the last years, and they have become useful tools for many applications on a broad variety of samples. This review focuses on miniaturized NIR instruments from an analytical point of view, to give an overview of the analytical strategies used in order to help the reader to set up their own analytical methods, from the sampling to the data analysis. It highlights the uses of these instruments, providing a critical discussion including current and future trends.
View Article and Find Full Text PDFMiniaturised near-infrared (NIR) instruments have been increasingly used in the last few years, and they have become useful tools for many applications on different types of samples. The market already offers a wide variety of these instruments, each one having specific requirements for the correct acquisition of the instrumental signal. This paper presents the development and optimisation of different measuring strategies for two miniaturised NIR instruments in order to find the best measuring conditions for the rapid and low-cost analysis of olive oils.
View Article and Find Full Text PDFThis work reports the simple and inexpensive fabrication of homemade paper-based carbon-printed electrodes (HP C-PEs), aiming to produce an alternative way to generate electrochemical biosensors to all and promoting their wide use. This is especially important in times of pandemics, considering the excellent features of electrochemical biosensing, which may ensure portability, low-cost and quick responses. HP C-PEs were fabricated using a standard cellulose filter paper that was first modified with wax, to make it hydrophobic.
View Article and Find Full Text PDFThe miniaturisation of analytical devices, reduction of analytical data acquisition time, or the reduction of waste generation throughout the analytical process are important requirements of modern analytical chemistry, and in particular of green analytical chemistry. Green analytical chemistry has fostered the development of a new generation of miniaturized near-infrared spectroscopy (NIR) spectrometric systems. However, one of the drawbacks of these systems is the need for a compromise between the performance parameters (accuracy and sensitivity) and the aforementioned requirements of green analytical chemistry.
View Article and Find Full Text PDFThe role of hydrogen peroxide in a wide range of biological processes has led to a steady increase in research into hydrogen peroxide determination in recent years, and conducting polymers have attracted much interest in electrochemistry as promising materials in this area. We present an overview of electrochemical devices for hydrogen peroxide determination using conducting polymers, either as a target or as a byproduct of redox reactions. We describe different combinations of electrode modifications through the incorporation of conducting polymers as the main component along with other materials or nanomaterials.
View Article and Find Full Text PDFIn this communication we present a potentiometric aptasensor based on chemically modified graphene (transducer layer of the aptasensor) and aptamers (sensing layer). Graphene oxide (GO) and reduced graphene oxide (RGO) are the basis for the construction of two versions of the aptasensor for the detection of a challenging living organism such as Staphylococcus aureus. In these two versions, DNA aptamers are either covalently (in the GO case) or non-covalently (in the RGO case) attached to the transducer layer.
View Article and Find Full Text PDFHydroponics is a water, energy, space, and cost efficient system for growing plants in constrained spaces or land exhausted areas. Precise control of hydroponic nutrients is essential for growing healthy plants and producing high yields. In this article we report for the first time on a new computer-operated analytical platform which can be readily used for the determination of essential nutrients in hydroponic growing systems.
View Article and Find Full Text PDFIn this paper we present a new generation of potentiometric biosensors based on carbon nanotubes (transducer layer of the biosensor) and aptamers (sensing layer of the biosensor) for the ultralow and selective detection of microorganisms. We show that with these aptasensors we were able to detect a few CFU of the target bacteria almost in real-time, both in buffered and in real samples.
View Article and Find Full Text PDFA new paper-based chemiresistor composed of a network of single-wall carbon nanotubes (SWCNTs) and anti-human immunoglobulin G (anti-HIgG) is reported herein. SWCNTs act as outstanding transducers because they provide high sensitivity in terms of resistance changes due to immunoreaction. As a result, the resistance-based biosensor reaches concentration detection as low as picomolar.
View Article and Find Full Text PDFPotentiometric sensing represents the preferred technique in many routine measurements of pH and ions. Unfortunately, the simplicity of the technique has not been exploited so far in high throughput biomolecular sensing. In this work, we demonstrate the capabilities of the hybrid functional material carbon nanotubes/aptamer for the creation of a new generation of nuclease-resistant aptasensors using the potentiometric transduction capabilities of single-walled carbon nanotubes in combination with the recognition capabilities of a protein-specific RNA aptamer.
View Article and Find Full Text PDFThe viability and performance of using a silicon photomultiplier (SiPM) in atmospheric lidar applications is experimentally compared against the well-established use of photomultiplier tubes. By using a modified lidar setup for simultaneous data acquisition of both types of sensors, we demonstrate that a SiPM can offer appropriate qualities for this specific application where the detection of fast, extremely low light pulses and large dynamic range signals are essential capabilities. The experimental results show that the SiPM has an appropriate behaviour offering suitable capabilities for elastic, backscatter aerosol lidars.
View Article and Find Full Text PDFIn this paper we report the first biosensor that is able to detect Staphylococcus aureus in real-time. A network of single-walled carbon nanotubes (SWCNTs) acts as an ion-to-electron potentiometric transducer and anti-S. aureus aptamers are the recognition element.
View Article and Find Full Text PDFIn this study, we developed a potentiometric planar strip cell based on single-walled carbon nanotubes that aims to exploit the attributes of solid-contact ion-selective electrodes for decentralized measurements. That is, the ion-selective and reference electrodes have been simultaneously miniaturized onto a plastic planar substrate by screen-printing and drop-casting techniques, obtaining disposable strip cells with satisfactory performance characteristics (i.e.
View Article and Find Full Text PDFIn this technical note, we report a new all-solid-state planar reference electrode based on single-walled carbon nanotubes and photocured poly(n-butylacrylate) (poly(nBA)) membrane containing the Ag/AgCl/Cl(-) ion system. Single-walled carbon nanotubes functionalized with octadecylamide (SWCNT-ODA) and deposited by drop-casting onto a disposable screen-printed electrode are an excellent all-solid-state transducer. The novel potentiometric planar reference electrode shows low potential variability (calibration slopes inferior to 2 mV/dec) for a wide range of chemical species (i.
View Article and Find Full Text PDFA novel potentiometric solid-state reference electrode containing single-walled carbon nanotubes as the transducer layer between a polyacrylate membrane and the conductor is reported here. Single-walled carbon nanotubes act as an efficient transducer of the constant potentiometric signal originating from the reference membrane containing the Ag/AgCl/Cl(-) ions system, and they are needed to obtain a stable reference potentiometric signal. Furthermore, we have taken advantage of the light insensitivity of single-walled carbon nanotubes to improve the analytical performance characteristics of previously reported solid-state reference electrodes.
View Article and Find Full Text PDFWe present an active null test system adapted to test lenses and wavefronts with complex shapes and strong local deformations. This system provides greater flexibility than conventional static null tests that match only a precisely positioned, individual wavefront. The system is based on a cylindrical Shack-Hartmann wavefront sensor, a commercial liquid crystal programmable phase modulator (PPM), which acts as the active null corrector, enabling the compensation of large strokes with high fidelity in a single iteration, and a spatial filter to remove unmodulated light when steep phase changes are compensated.
View Article and Find Full Text PDFDetecting and identifying pathogen bacteria is essential to ensure quality at all stages of the food chain and to diagnose and control microbial infections. Traditional detection methods, including those based on cell culturing, are tedious and time-consuming, and their further application in real samples generally implies more complex pretreatment steps. Even though state-of-the-art techniques for detecting microorganisms enable the quantification of very low concentrations of bacteria, to date it has been difficult to obtain successful results in real samples in a simple, reliable, and rapid manner.
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