Indirect determination of formaldehyde by square-wave voltammetry based on the electrochemical oxidation of 3,5–diacetyl–1,4–dihydrolutidine using an unmodified glassy-carbon electrode

Simultaneous reflectance and fluorescence measurements for portable formaldehyde determination in milk using a multi-channel spectrometer sensor

This study introduces a novel optical method for formaldehyde determination in milk, based on the hypothesis that simultaneous reflectance and fluorescence measurements can enhance detection sensitivity compared to traditional methods. We aimed to address the challenge of accurately measuring low concentrations of formaldehyde in milk, a crucial issue for food safety. By employing a multi-channel spectrometer sensor and exploiting the reaction of formaldehyde with acetylacetone to form 3,5-diacetyl-1,4-dihydrolutidine (DDL), we measured reflectance of DDL at 415 nm and fluorescence at 515 nm. The method demonstrated linearity (0.1-4 mg L-1 for reflectance, 0.1-3 mg L-1 for fluorescence) with detection limits of 0.027 mg L-1 (reflectance) and 0.030 mg L-1 (fluorescence). We successfully determined formaldehyde in milk samples (46 to 114 μg L-1) and observed a 60 % reduction in formaldehyde concentrations. This research underscores the importance of heat treatment in ensuring food safety.

Trends in pulse voltammetric techniques applied to foodstuffs analysis: The food additives detection

Food additives are chemical compounds intentionally added during foodstuff production to control technological functions, such as pH, viscosity, stability (color, flavor, taste, and odor), homogeneity, and loss of nutritional value. These compounds are fundamental in inhibition the degradation process and prolonging the shelf life of foodstuffs. However, their inadequate employment or overconsumption can adversely affect consumers' health with the development of allergies, hematological, autoimmune, and reproductive disorders, as well as the development of some types of cancer. Thus, the development and application of simple, fast, low-cost, sensitivity, and selectivity analytical methods for identifying and quantifying food additives from various chemical classes and in different foodstuffs are fundamental to quality control and ensuring food safety. This review presents trends in the detection of food additives in foodstuffs using differential pulse voltammetry and square wave voltammetry, the main pulse voltammetric techniques, indicating the advantages, drawbacks, and applicability in food analysis. Are discussed the importance of adequate choices of working electrode materials in the improvements of analytical results, allowing reliable, accurate, and inexpensive voltammetric methods for detecting these compounds in foodstuffs samples.

Recent Advances in Electrochemical Sensors for Formaldehyde

Formaldehyde, a ubiquitous indoor air pollutant, plays a significant role in various biological processes, posing both environmental and health challenges. This comprehensive review delves into the latest advancements in electrochemical methods for detecting formaldehyde, a compound of growing concern due to its widespread use and potential health hazards. This review underscores the inherent advantages of electrochemical techniques, such as high sensitivity, selectivity, and capability for real-time analysis, making them highly effective for formaldehyde monitoring. We explore the fundamental principles, mechanisms, and diverse methodologies employed in electrochemical formaldehyde detection, highlighting the role of innovative sensing materials and electrodes. Special attention is given to recent developments in nanotechnology and sensor design, which significantly enhance the sensitivity and selectivity of these detection systems. Moreover, this review identifies current challenges and discusses future research directions. Our aim is to encourage ongoing research and innovation in this field, ultimately leading to the development of advanced, practical solutions for formaldehyde detection in various environmental and biological contexts.

Fluorimetric determination of aqueous formaldehyde employing heating and ultrasound-assisted approach through its derivatization with a ß-diketone-nickel(2+) complex immobilized in a PMMA flow cell

Formaldehyde (FA) is a highly toxic substance present in many matrices, including freshwater as well as found in natural mechanisms such as rainfall and combustion of organic matter. Consumption of water contaminated with high levels of FA can cause severe short-term or long-term health problems. Due to these health risks, procedures are necessary to determine and quantify FA in aqua sources This paper reports on a study of fluorimetric determination of FA using a nickel(2 + )-diketonate coordination compound immobilized as a solid precursor. The compound was characterized by electronic absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetry (TG), optical microscopy (OM), and scanner electron microscopy (SEM). The methodology was based on the reaction of the synthesized compound with an ammoniacal buffer generating a selective reagent for formaldehyde: fluoral-P. The product of the reaction generates 3,5-diacetyl-1,4-dihydrolutidine (DDL), which is responsible for the fluorescence of the system. Several parameters such as temperature, duration of heating time, and dilution effect with the best effects were studied to carry out FA determination. Under the optimum experimental conditions, a linear response ranging from 1.0 to 10.0 mg/L FA (R = 0.997 and n = 10), and a detection (3σ criterion) and quantification (10 σ criterion) limit estimated at 0.129 and 0.389 mg/L, respectively were achieved. The FA analysis was able to be conducted in 05 min with a relative standard deviation estimated at 1.10 %.

Development of a portable optical device with a multi-channel spectrometer sensor for quantification of glycerol in wine: a maker approach for on-site analysis

In this work we present a novel and environmentally friendly approach for quantifying glycerol in wine samples using a portable optical device based on the maker concept and do-it-yourself (DIY) principles. This method offers significant advantages, including cost-effectiveness, reduced sample and reagent consumption, and the potential for integrating IoT (Internet of Things) technology. The chemical strategy involves the oxidation of glycerol using periodate, followed by the formation of the 3,5-diacetyl-1,4-dihydrolutidine (DDL) compound through a reaction with acetylacetone. The utilization of a cost-effective AS7341 color sensor as a detector enables accurate and sensitive detection of glycerol levels in wine samples. The optimized procedure demonstrates adequate analytical performance for glycerol determination in wine samples, encompassing a wide linear range (0.5 mg L-1 to 40.0 mg L-1), high correlation coefficient (r = 0.998), and low limits of detection (0.050 mg L-1). The method exhibits excellent precision, with the coefficient of variation estimated to be 0.1% for 10 independent measurements of a 20 mg L-1 solution. These features render it suitable not only for routine glycerol analysis in the wine industry, but also for addressing challenges related to wine adulteration and counterfeiting.

Bismuth-coated screen-printed electrodes for the simple voltammetric determination of formaldehyde

For the first time, bismuth modified electrodes have been used for the voltammetric detection of formaldehyde (FM). The well-known method of forming formaldehyde hydrazone (FAH) in the presence of hydrazine sulphate was used to convert the hydrated form of FM into its electrochemically active derivative. Various experimental conditions for differential pulse voltammetry were studied to achieve the best analytical performance. The FAH reduction current (FM response) reaches its maximum value at a pH of a phosphate buffer solution of 5.2 ± 0.1 in the presence of 0.09-0.12 M hydrazine sulfate on a bismuth film preliminarily precipitated for 8-12 min from acidic Bi(III) acetate solutions at an electrolysis potential of -1.0 V on the surface of a screen-printed carbon electrode (SPCE). A dendritic-like film structure was created on the SPCE surface. Under the optimized conditions a linear calibration curve over the range of 0.01-5 mg L^-1 (0.33-167 μM) FM was achieved, with a detection limit of 0.002 mg L^-1 (0.06 μM). The determination of FM in waste water, melt water from snow within the city industrial zone, and a widely used pharmaceutical preparation "Endofalk®" with good results revealed the potential applicability of a bismuth modified SPCE (BiSPCE) for trace analysis.

A new electroanalytical methodology for the determination of formaldehyde in wood-based products

A new electroanalytical methodology was developed for the sensitive and selective determination of formaldehyde in wood-based products (WBPs), featuring an extraction process using a Headspace Liquid Acceptor System (HLAS), and detection by square-wave voltammetry (SWV) on unmodified screen-printed carbon electrodes (SPCEs). HLAS, here presented for the first time, captures and derivatizes formaldehyde released from the sample by using the acetylacetone reagent as acceptor solution. The product of formaldehyde with acetylacetone, in the presence of ammonium salt, is 3,5-diacetyl-1,4-dihydrolutidine (DDL) which we have found to be electrochemically active at unmodified SPCEs, generating a selective oxidation peak at +0.4 V. Detection and quantification limits of 0.57 and 1.89 mg kg^-1 were obtained, together with intra- and inter-day precisions below 10% (as relative standard deviation, RSD). The methodology was used to determine formaldehyde content in seven WBPs, with similar results being obtained by the developed HLAS-SPCE method and the European standard method EN 717-3, with a profound reduction of total analysis time. The developed HLAS-SPCE combines the use of a new sample preparation procedure for volatiles with, as far as we know, the first determination of formaldehyde (as the derivative product, DDL) on unmodified SPCEs, offering a promising alternative for the determination of formaldehyde in WBPs and other samples.

Focusing surface acoustic waves assisted electrochemical detector in microfluidics

This article demonstrates a novel electrochemical detection device. The device is composed by two focusing interdigital transducers for exciting focused surface acoustic waves by applying an AC signal, a three-electrode system for electrochemical measurement, and a liquid pool for holding liquid on a LiNbO₃ wafer. The amperometry current of ferrocenecarboxylic acid and potassium phosphate buffer solution is used to characterize the detection sensitivity. Two experiments are carried out to optimize the device design. The result shows that the two focusing interdigital transducers with arc degree 30° and distance 5 mm can remarkably enhance the liquid mixing rate. Under this condition, the oxidation current is about 27 times larger than that without surface acoustic wave stirring.

Voltammetric sensing of formaldehyde by using a nanocomposite prepared by reductive deposition of palladium and platinum on polypyrrole-coated nitrogen-doped reduced graphene oxide

The study presents the synthesis of polypyrrole-coated palladium platinum/nitrogen-doped reduced graphene oxide nanocomposites (PdPt-PPy/N-rGO NC) via direct the reduction of Pd(II) and Pt(II) in the presence of pyrrole monomer, N-rGO and L-cysteine as the reducing agent. X-ray diffraction confirmed the presence of metallic Pd and Pt from the reduction of Pd and Pt cations. Transmission electron microscopy images revealed the presence of Pd, Pt and PPy deposition on N-rGO. Impedance spectroscopy results gave a decreased charge transfer resistance due to the presence of N-rGO. The nanocomposites were synthesized with different Pd/Pt ratios (2:1, 1:1 and 1:2). A glassy carbon electrode (GCE) modified with the nanocomposite showed enhanced electrochemical sensing capability for formaldehyde in 0.1 M sulfuric acid solution. Cyclic voltammetry showed an increase in the formaldehyde oxidation peak current at the GCE modified with Pd₂Pt₁ PPy N-rGO. At a typical potential of 0.45 V (vs. SCE), the sensitivity in the linear segment was 345.8 μA.mM ^-1. cm^-2. The voltammetric response was linear between 0.01 and 0.9 mM formaldehyde concentration range, with a 27 µM detection limit (at S/N = 3). Graphical abstract Schematic presentation of formaldehyde detection by Pd₂Pt₁-PPy/nitrogen-doped reduced Graphene Oxide Nanocomposite (Pd₂Pt₁-PPy /N-Gr NC). The decrease of charge transfer resistance and the agglomeration of deposited metals in the presence of N-rGO enhance the current response of the electrochemical sensor.