Scaling the Analytical Information Given by Several Types of Colorimetric and Spectroscopic Instruments Including Smartphones: Rules for Their Use and Establishing Figures of Merit of Solid Chemosensors

Towards a zero liquid discharge process from brine treatment: Water recovery, nitrate electrochemical elimination and potential valorization of hydrogen and salts

This research addresses the issues related with treatment and valorization of brines and nitrate decontamination of surface and ground waters. The objective was to approximate to zero liquid discharge (ZLD) minimizing the environmental impact of brines of an electrodialysis reversal water treatment plant (EDRWTP) as an example. The innovative in flow process was developed from lab to pre-industrial scale and joined several main concepts: ion-exchange equilibrium for softening or demineralization of brines; reversed osmosis to recover suitable water and to enrich the waste in nitrate for efficient electrochemical reduction of NO3- to N2; valorization of subproducts by direct use or by precipitation; and assessment of the whole process by measuring in-line several parameters. The achieved softening was around 98 % and the recovered water from this current by reversed osmosis was 75 %. The brine of this step (25 %) contained around 1500 mg/L of nitrate and it was treated by electrochemical reduction with a Bi/Sn cathode providing a gas current of 60 % of initial nitrate reduced to N2, O2, H2O, NH3 and at least 97 % of H2. The aqueous current contained around 40 % of initial nitrate as ammonium and nitrite lower than 50 and 5 mg/L, respectively. Hypochlorite was added to this last current for oxidizing ammonium and nitrite to N2 and nitrate, respectively, being nitrate and ammonium lower than 50 and 5 mg/L, respectively. After the obtained water was demineralized and conducted to the EDRWTP inlet. The recovery of insoluble salts as calcium carbonate, reuse of saline solutions for the regeneration of process resins and the potential use of hydrogen generated as a by-product during the electrochemical reduction are other possible utilities.

Portable determinations for legislated dissolved nitrogen forms in several environmental water samples as a study case

In this work, we have studied the main species involved in determining total dissolved nitrogen (TDN) in water samples for accommodating a variety of quantitation methodologies to portable instruments and with the goal to achieve in situ analysis. The rise of water eutrophication is becoming an ecological problem in the world and TDN contributes markedly to this. Traditionally the several forms of DN are measured in the laboratory using conventional instrumentation from grab samples, but their analysis in place and in real time is a current demand. Inorganic nitrogen: NO₃^-, NO₂^- and NH₄⁺, and organic nitrogen, such as amino nitrogen were tested here. For nitrate that presents native UV absorption suitable for direct water analysis, a portable optical fiber probe was compared with benchtop equipment and an in place analyzer. For nitrate, nitrite and ammonium, in situ solid devices that deliver reagents needed were tested and water color was measured by a smartphone coupled with a miniaturized optical fiber spectrometer and a miniaturized spectrometer or from images obtained and their RGB components. Amino nitrogen of some aromatic aminoacids with native fluorescence was followed by a portable optical fiber probe. Organic amino nitrogen and ammonium were determined by a portable luminometer and luminol supported in a measurement tube. Moreover, a portable miniaturized liquid chromatograph was shown suitable for monitoring priority nitrogen environmental pollutants. All options provided suitable results in comparison with lab estimations and were useful for evaluating if the legislation is fulfilled for the variety of tested waters. A discussion about the several portable options proposed for in place analysis, in function of the legislated determinations needed for each type of water was carried out.

Functional Micro-/Nanostructures in Agrofood Science: Precise Inspection, Hazard Elimination, and Potential Health Risks

Nanotechnology, biotechniques, and chemical engineering have arisen as new trends with significant impacts on agrofood science development. Advanced analytical techniques with high sensitivity, specificity, and automation based on micro-/nanomaterials for food hazard elimination have become leading research hotspots in agrofood science. Research progress in micro-/nanomaterials has provided a solid theoretical basis and technical support to solve problems in the industry. However, the rapid development of micro-/nanostructures has also raised concerns regarding potential risks to human health. This review presents the latest advances in the precise inspection and elimination of food hazards from micro-/nanomaterials and discusses the potential threats to human health posed by nanomaterials. The theoretical reference was provided for the application trend of micro-/nanomaterials in the field of agrofood science in the future.

Advances in the Measurement of Polymeric Colorimetric Sensors Using Portable Instrumentation: Testing the Light Influence

Sustainable and green sensors based on polydimethyl siloxane (PDMS) or cellulose polymers, as a case of study of the use of portable instrumentation joined to a smartphone, have been tested. A smartphone camera was used to obtain images and was also coupled to a minispectrometer, without and with an optical fiber probe to register spectra. To study light influence on the analytical signal, light-emitting diode (LED), halogen light and daylight have been assayed. A corrective palette of 24 colors and a set with 45 colors from different color ranges were used as the validation set. The results indicated that halogen light was the best option to obtain the spectra. However, for digital image analysis, it was the LED light that gave a greater approximation of the RGB values of the real colors. Based on these results, the spectra and the RGB components of PDMS solid sensors doped with 1,2-naphtoquinone-4-sulfonate (NQS) for the determination of ammonium in water or urea in urine, PDMS doped with Griess reagent for developing the assay of nitrite in waters and cellulose sensors for the determination of hydrogen sulfide in the atmospheres have been obtained. The results achieved were good in terms of sensitivity and linearity and were comparable to those obtained using a laboratory benchtop instrument. Several rules for selecting the most suitable light source to obtain the spectra and/or images have been established and an image correction method has been introduced.

A Portable Fluorescent Hydrogel-Based Device for On-Site Quantitation of Organophosphorus Pesticides as Low as the Sub-ppb Level

Portable devices possess powerful application prospects in on-site sensing without the limitation of bulky instruments. Given the relevance of pesticides to food safety, we herein fabricated a robust gold nanocluster (AuNC)-based hydrogel test kit for precisely quantified chlorpyrifos by using a three-dimensional (3D) printed subsidiary device. In this work, the fluorescence of AuNC-based hydrogel could be efficiently quenched by cobalt oxyhydroxide nanoflakes (CoOOH NFs) through the Förster resonance energy transfer effect. Chlorpyrifos as an acetylcholinesterase inhibitor controls the enzymatic hydrolysis reaction and further regulates the production of thiocholine that could decompose CoOOH nanoflakes into Co2+, resulting in the fluorescence response of AuNC-based hydrogel. By using a homemade subsidiary device and smartphone, the fluorescence color was transformed into digital information, achieving the on-site quantitative detection of chlorpyrifos with the limit of detection of 0.59 ng ml−1. Owing to specific AuNC signatures and hydrogel encapsulation, the proposed fluorescence hydrogel test kit displayed high sensitivity, good selectivity, and anti-interference capability in a real sample analysis, providing great potential in on-site applications.

Improving Sustainability of the Griess Reaction by Reagent Stabilization on PDMS Membranes and ZnNPs as Reductor of Nitrates: Application to Different Water Samples

A new approach based on the use of polydimethylsiloxane (PDMS) membranes doped with Griess reagents for in situ determination of NO2− and NO3−^- in real samples is proposed. The influence of some doping compounds, on the properties of the PDMS membranes, such as tetraethyl orthosilicate (TEOS), or/and ionic liquids (OMIM PF₆) has been studied. Membrane characterization was performed. To apply the procedure to NO3− determination, dispersed Zn nanoparticles (ZnNPs) were employed. The analytical responses were the absorbance or the RGB components from digital images. Good precision (RSD < 8%) and detection limit of 0.01 and 0.5 mgL⁻¹ for NO2− and NO3−, respectively, were achieved. The approach was satisfactory when applied to the determination of NO2− and NO3− in drinking waters, irrigation and river waters, and waters from canned and fresh vegetables. The results obtained were statistically comparable with those by using nitrate ISE or UV measurement. This approach was transferred satisfactory to 96 wells for multianalysis. This study enables the improvement in the on-site determination of NO2− and NO3− in several matrices. It is a sustainable alternative over the reagent derivatizations in solution and presents several advantages such as being versatile, simplicity, low analysis time, cost, and energy efficiency. The response can be detected visually or by portable instruments such as smartphone.

Combining high performance thin layer chromatography with minispectrometer-fiber optic probe-coupled to smartphone for in place analysis: Lactose quantification in several matrices

An in place colorimetric method has been proposed for estimation of the quantity of lactose in several matrix (milk, water effluents and surfaces). Analyzing the amount of this carbohydrate it can be control the product, the cleanliness of the parts of the dairy companies and it can avoid contamination of milk products produced there. This method combines the use of HPTLC for sugars separation with novel analytical devices as minispectrophotometer with fiber optic coupled to a smartphone. In order to measure the lactose a colorimetric reaction has been used. Variable volumes of samples or stock solutions were deposited in nano-silica gel layer, a mobile phase of acetonitrile:water:acetic acid was used for carbohydrate separation and a solution of thymol (0.05 g Thymol in 95 mL of EtOH and 5 mL H₂SO₄) was used for revealed the carbohydrate spot. Finally, the reflectance of samples and stock solutions were measured. The achieved limits of detection were 0.03 mg mL^-1 and 0.003 mg mL^-1 for the working concentration range and the analysis at traces level respectively.

Integration of personalized drug delivery systems into digital health

Personalized drug delivery systems (PDDS), implying the patient-tailored dose, dosage form, frequency of administration and drug release kinetics, and digital health platforms for diagnosis and treatment monitoring, patient adherence, and traceability of drug products, are emerging scientific areas. Both fields are advancing at a fast pace. However, despite the strong complementary nature of these disciplines, there are only a few successful examples of merging these areas. Therefore, it is important and timely to combine PDDS with an increasing number of high-end digital health solutions to create an interactive feedback loop between the actual needs of each patient and the drug products. This review provides an overview of advanced design solutions for new products such as interactive personalized treatment that would interconnect the pharmaceutical and digital worlds. Furthermore, we discuss the recent advancements in the pharmaceutical supply chain (PSC) management and related limitations of the current mass production model. We summarize the current state of the art and envision future directions and potential development areas.