4-hydrazinobenzoic acid as a derivatizing agent for aldehyde analysis by HPLC-UV and CE-DAD

Applications of Microextraction Technology for the Analysis of Alcoholic Beverages Quality: Current Perspectives and Future Directions

Alcoholic beverages are loved by the majority of consumers because of their diverse characteristics and rich nutritional value; thus, ensuring their quality is necessary for maintaining the rapid development of the alcoholic beverage industry. Due to trace levels of various quality factors and the complexity of the beverage body matrix, pretreatment is usually required before analysis. Among the many pretreatment methods available, microextraction has attracted increasing attention because it aligns with the development direction of green chemistry. This review surveys advancements in microextraction techniques pertaining to three quality aspects in the most frequently consumed alcoholic beverages: baijiu and huangjiu (spirits) and wine and beer (fermented alcoholic drinks). Furthermore, new directions in their development are discussed.

A new derivatizing reagent for the determination of 5-nitro-2-furaldehyde in trout muscle by liquid chromatography-tandem mass spectrometry

The 5-nitro-2-furaldehyde (5-NF) is an aldehyde aromatic organic compound that has been envisaged as an alternative marker for detecting nitrofurazone treatment abuse and to avoid the false positive results induced by the semicarbazide. Analyzing 5-NF presents challenges, and its derivatization reaction with hydrazine reagents is required to enhance the capability of its detection and its identification. This study aims at developping an analytical method for 5-NF determination in trout muscle samples based on chemical derivatization prior to analysis by liquid chromatography-tandem mass spectrometry. Four commercially available hydrazine reagents, namely: N,N-Dimethylhydrazine (DMH), 4-Hydrazinobenzoic acid (HBA), 2,4-Dichlorophenylhydrazine (2,4-DCPH) and 2,6-Dichlorophenylhydrazine (2,6-DCPH) were proposed for the first time as derivatizing reagents in the analysis of 5-NF. The derivatization reaction was simultaneously performed along with the extraction method in acidic condition using ultrasonic assistance and followed by liquid extraction using acetonitrile. The efficiency of the chemical reaction with 5-NF was examined and the reaction conditions including the concentration of hydrochloric acid, pH, temperature, reaction time and the concentration of the derivatizing reagents were optimized. Experiments with fortified samples demonstrated that 2,4-DCPH derivatizing reagent at 20 mM for 20 min of ultrasonic treatment under acidic condition (pH 4) gave an effective sample derivatization method for 5-NF analysis. Under the optimized conditions, the calibration curves were linear from 0.25 to 2 μg kg-1 with coefficient of determination >0.99. The recoveries ranged from 89 % to 116 % and precision was less than 13 %. The limit of detection and quantification were 0.1 and 0.2 μg kg-1, respectively.

Chromatographic Methods and Sample Pretreatment Techniques for Aldehydes, Biogenic Amine, and Carboxylic Acids in Food Samples

This review paper critically examines the current state of research concerning the analysis and derivatization of aldehyde, aromatic hydrocarbons and carboxylic acids components in foods and drinks samples, with a specific focus on the application of Chromatographic techniques. These diverse components, as vital contributors to the sensory attributes of food, necessitate accurate and sensitive analytical methods for their identification and quantification, which is crucial for ensuring food safety and compliance with regulatory standards. In this paper, High-Performance Liquid Chromatography (HPLC) and Gas Chromatographic (GC) methods for the separation, identification, and quantification of aldehydes in complex food matrices were reviewed. In addition, the review explores derivatization strategies employed to enhance the detectability and stability of aldehydes during chromatographic analysis. Derivatization methods, when applied judiciously, improve separation efficiency and increase detection sensitivity, thereby ensuring a more accurate and reliable quantification of aldehyde aromatic hydrocarbons and carboxylic acids species in food samples. Furthermore, methodological aspects encompassing sample preparation, chromatographic separation, and derivatization techniques are discussed. Validation was carried out in term of limit of detections are highlighted as crucial elements in achieving accurate quantification of compounds content. The discussion presented by emphasizing the significance of the combined HPLC and GC chromatography methods, along with derivatization strategies, in advancing the analytical capabilities within the realm of food science.

Selective determination of formaldehyde by high-performance liquid chromatography with porous graphitic carbon column using N,N'-bis(9-anthrylmethyl)propane-1,3-diamine as derivatizing reagent

Aromatic compounds containing two secondary amino groups were designed and prepared as new derivatizing reagents for aldehydes. One of them, N,N'-bis(9-anthrylmethyl)propane-1,3-diamine (APD), could achieve selective determination of formaldehyde (FA) on a porous graphitic carbon (PGC) column using xylenes, chlorobenzene, and 1-chloronaphthalene as mobile phases by high-performance liquid chromatography (HPLC). The APD-FA derivative was eluted from the PGC column, while the other APD-aldehyde derivatives remained on the column during the HPLC measurements. This specific elution was not observed using mobile phases such as acetonitrile, 1,4-dioxane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, chloroform, benzene, toluene, benzyl alcohol, 2-ethyl-1-hexanol, and pyridine. The APD-FA derivative had a six-membered ring of two tertiary amines identified using ¹H NMR spectroscopy. When the π-π interaction of the solvent molecule of the mobile phase with PGC overcame that between the APD-FA derivative and PGC, the APD-FA derivative could be eluted from the column. The best resolution between the peak of the APD-FA derivative and that of free APD was observed when using o-xylene. The optimum derivatization and the HPLC conditions for selective HPLC determination of FA were to conduct the derivatization of FA by heating in an aqueous phase with APD in o-xylene at 100 °C. In this method, FA could be derivatized with APD at a mildly neutral pH of 6.7, unlike the low pH required for the derivatization of aldehydes with 2,4-dinitrophenylhydrazine (DNPH), which is commonly used for the derivatization of aldehydes. The detection and quantification limits of FA were 0.8 and 3.5 ng mL^-1 in this HPLC method with fluorescent detection, respectively. This selective HPLC method could be applied to the determination of FA in various water samples. It was found that only APD among the derivatizing reagents containing two secondary diamines was useful for the selective determination of FA.

Helicene-Hydrazide Encapsulated Ethyl Cellulose as a Potential Fluorescence Sensor for Highly Specific Detection of Nonanal in Aqueous Solutions and a Proof-of-Concept Clinical Study in Lung Fluid

Over the past years, lung cancer has been one of the vital cancer-related mortalities worldwide and has inevitably exhibited the highest death rate with the subsequent need for facile and convenient diagnosis approaches to identify the severity of cancer. Previous research has reported long-chain aldehyde compounds such as hexanal, heptanal, octanal, and nonanal as potential biomarkers of lung cancer. Herein, the helicene dye-encapsulated ethyl cellulose (EC@dye-NH) nanosensors have been applied for the potentially sensitive and specific detection of long-chain aldehydes in aqueous media. The sensors contain the intrinsic hydrazide group of dye-NH, which is capable of reacting an aldehyde group via imine formation and the EC backbone. This offers the synergistic forces of hydrophobic interactions with alkyl long-chain aldehydes, which could induce self-assembly encapsulation of EC@dye-NH nanosensors and strong fluorescence responses. The addition of long-chain aldehyde would induce the complete micellar-like nanoparticle formation within 15 min in acetate buffer pH 5.0. The limit of detection (LOD) values of EC@dye-NH nanosensors toward heptanal, octanal, and nonanal were 40, 100, and 10 μM, respectively, without interference from the lung fluid matrices and short-chain aldehydes. For practical applicability, this sensing platform was developed for quantification of the long-chain aldehydes in lung fluid samples with 98-101% recoveries. This EC@dye-NH nanosensor was applied to quantify nonanal contents in lung fluid samples. The results of this method based on EC@dye-NH nanosensors were then validated using standard gas chromatography-mass spectrometry (GC-MS), which gave results consistent with the proposed method. With intracellular imaging application, the EC@dye-NH nanosensors demonstrated excellent intracellular uptake and strong green fluorescence emission upon introducing the nonanal into the lung cancer cells (A549). Thus, the developed nanosensing approach served as the potential fluorescent probes in medical and biological fields, especially for lung cancer disease diagnosis based on highly selective and sensitive detection of long-chain aldehydes.

Determination of methanol-derivatives in drying oils after metal oxide-based dispersive solid phase extraction/QuEChERS clean-up

The determination of secondary volatile degradation products in drying oil extracts is substantial to prevent formation of undesirable metal formates in paintings and/or other artefacts. This study develops a simple, cost-effective, and reliable, high-performance liquid chromatography with diode array detector (HPLC-DAD) method to determine three secondary volatile degradation products (methanol, formaldehyde, and formic acid) in drying oils, including linseed, poppy-seed, and walnut oil. Extraction of analytes was performed using QuEChERS-based procedure followed by metal oxide-based dispersive solid-phase extraction (d-SPE) clean-up and presented a good performance for all of the volatile analytes of interest with recoveries in the range of 90-120% after application of the nanostructured cerium oxide-based (CeO₂) and zirconia-based (ZrO₂) sorbents prepared by favorable and ecological-friendly methods. With a new clean-up solution for samples with high-fat content, it was possible to achieve higher recoveries than with commercial Z-Sep/C18 sorbent. In all cases, relative standard deviations (RSD) of less than 10% were achieved. No significant matrix interference was observed due to the application of effective sorbents in nanostructured form. The developed method was applied to samples of drying oils, and it was found that after storage for three months, all methanol was most likely oxidized to formaldehyde and formic acid. The concentrations of formaldehyde were in the range of 260 - 304 μg∙g^-1, while formic acid concentrations ranged between 72 - 386 μg∙g^-1. The highest concentration of formaldehyde (304 μg∙g^-1) and formic acid (386 μg∙g^-1) was found in linseed oil.

Evaluation of air quality in indoor and outdoor environments: Impact of anti-COVID-19 measures

This study monitors the presence of 88 volatile organic compounds (VOCs) and semi-volatile organic compounds (semi-VOCs) at the gas phase of seven indoor settings in a school in the city of Tarragona, Spain, and five outdoor locations around the city. The VOCs and semi-VOCs monitored were solvents (∑Solvents), aldehydes (∑Aldehydes), emerging organic compounds (∑EOCs), and other VOCs and semi-VOCs (∑Others). Passive sampling campaigns were performed using Carbopack X tubes followed by thermal desorption coupled to gas chromatography with mass spectrometry (TD-GC-MS). Overall, 70 of the target compounds included in the method were determined in the indoor air samples analysed, and 42 VOCs and semi-VOCs in the outdoor air samples. Our results showed that solvents were ubiquitous throughout the school at concentrations ranging from 272 μg m^-3 to 423 μg m^-3 and representing 68%-83% of total target compounds (∑Total). The values of ∑Total in 2021 were three times as high as those observed at the same indoor settings in 2019, with solvents experiencing the greatest increase. A plausible explanation for these observations is the implementation of anti-COVID-19 measures in the indoor settings, such as the intensification of cleaning activities and the use of hydroalcoholic gels as personal hygiene. The ∑Total values observed in the indoor settings evaluated were twenty times higher than those found outdoors. ∑Solvents were the most representative compounds found indoors (74% of the ∑Total). The concentrations of VOCs and semi-VOCs observed in the outdoors were strictly related to combustion processes from automobile traffic and industrial activities, with ∑Others contributing 58%, ∑Solvents 31%, and ∑Aldehydes 11% of the ∑Total. EOCs, on the other hand, were not detected in any outdoor sample.

Occurrence, detection and ecotoxicity studies of selected pharmaceuticals in aqueous ecosystems- a systematic appraisal

Pharmaceutical compounds (PCs) have globally emerged as a significant group of environmental contaminants due to the constant detection of their residues in the environment. The main scope of this review is to fill the void of information on the knowledge on the African occurrence of selected PCs in environmental matrices in comparison with those outside Africa and their respective toxic actions on both aquatic and non-aquatic biota through ecotoxicity bioassays. To achieve this objective, the study focused on commonly used and detected pharmaceutical drugs (residues). Based on the conducted literature survey, Africa has the highest levels of ciprofloxacin, sulfamethoxazole, lamivudine, acetaminophen, and diclofenac while Europe has the lowest of all these PC residues in her physical environments. For ecotoxicity bioassays, the few data available are mostly on individual groups of pharmaceuticals whereas there is sparsely available data on their combined forms.

Gas-Diffusion Microextraction (GDME) Combined with Derivatization for Assessing Beer Staling Aldehydes: Validation and Application

In this work, a gas-diffusion microextraction (GDME) methodology was optimized and validated for the analysis of selected staling aldehydes (furfural (FURF), 2-methylpropanal (2-MP), 2-methylbutanal (2-MB), 3-methylbutanal (3-MB), and acetaldehyde (ACET)) during natural and forced aging of beer. The methodology was optimized considering time, temperature of extraction, and derivatizing agent. Using 4-hydrazinobenzoic acid (HBA) as a derivatizing agent, the performance of the method was evaluated by assessing several parameters such as detection limits (ranging from 1.2 to 1857.7 µg/L for 2-MB and ACET, respectively), quantification limits (ranging from 3.9 to 6192.4 µg/L for 2-MB and ACET, respectively), recoveries (higher than 96%), intraday and interday precisions (lower than 3.4 and 9.2%, respectively), and linearity (r² ≥ 0.995). During beer aging, higher content of Strecker aldehydes and FURF were found, while no significant variations in ACET levels were observed. In general, the aldehydes content assessed for beers stored at 37 ± 1 °C for 7 and 14 days mimics that observed for beers stored at 20 ± 2 °C for 3 and 6 months, respectively. Lower temperatures of storage (4 ± 1 °C) delayed the development of staling aldehydes. Based on PCA analysis, the content of staling aldehydes and beer color were responsible for 91.39% of the variance among the analyzed samples, and it was demonstrated that these are key parameters to discriminate fresh from aged beers. The results herein presented showed that the proposed analytic methodology is a valuable strategy for the characterization and quantification of important staling aldehydes in beer with a potential application in the quality control of beer during storage.

Disposable and low-cost electrochemical sensor based on the colorless nail polish and graphite composite material for tartrazine detection

A new method to manufacture electrochemical devices based on the graphite and colorless nail polish (N-grap) film was developed for tartrazine (Tz) detection. Scanning Electron Microscopy (SEM) demonstrates that the composite material presents a high porous carbon structure. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were employed to electrochemically characterize the electrode material, which corroborates the porous structure of the N-graph due to the enhanced electroactive area (5.4-fold increase) and presented a heterogeneous electron transfer rate constant (k0) of 5.82 × 10-3 cm s-1 for potassium ferricyanide. The electrochemical determination of the Tz was carried out using square-wave voltammetry (SWV), under the optimized experimental conditions, which showed high sensitivity (0.793 A L mol-1) and a lower limit of detection (LOD) of 2.10 × 10-8 mol L-1 with a linear concentration ranging from 2.0 to 50.0 μmol L-1. The developed sensor was applied for the analysis of Tz in sports drink samples and the result obtained by N-grap device was statistically compared with a spectrophotometric method demonstrating good accordance and the accuracy of the proposed method. Based on these results, we believe that this new fabrication method to produce disposable and low-cost electrochemical devices can be an alternative method for in-field analysis of dye in commercial sport drink samples and other relevant applications.

Production of Aldehydes by Biocatalysis

The production of aldehydes, highly reactive and toxic chemicals, brings specific challenges to biocatalytic processes. Absence of natural accumulation of aldehydes in microorganisms has led to a combination of in vitro and in vivo strategies for both, bulk and fine production. Advances in genetic and metabolic engineering and implementation of computational techniques led to the production of various enzymes with special requirements. Cofactor synthesis, post-translational modifications and structure engineering are applied to prepare active enzymes for one-step or cascade reactions. This review presents the highlights in biocatalytical production of aldehydes with the potential to shape future industrial applications.

The recent advance of organic fluorescent probe rapid detection for common substances in beverages

The beverage industry is confronted with tremendous challenges in terms of quality assurance. The allowed contents of common ingredients such as copper ions, hydrogen sulfide, cysteine and caffeine are stipulated by various governing bodies, and the beverage industry must ensure that it meets these requirements. Due to its unique advantages of high sensitivity, low cost and relatively low toxicity over high-performance liquid chromatography, atomic absorption spectrometry and nanomaterials, the use of organic fluorescent probes for the rapid detection of beverage contents has become a hot research topic. This review summarizes the detection of common substances in wine, tea, mineral water, milk and other beverages. Furthermore, the preparation of test paper and simple colour comparison are discussed to display the rapid qualitative capability of designed probes. To improve the current state of beverage safety, future trends and strategies for fast organic fluorescent probe detection in the beverage industry are also discussed.

Organochlorine pesticide analysis in milk by gas-diffusion microextraction with gas chromatography-electron capture detection and confirmation by mass spectrometry

Organochlorine pesticides (OCPs) are synthetic compounds less used nowadays due to their toxicity combined with slow degradation which leads to accumulation in the environment. Gas-diffusion microextraction (GDME) was employed prior to gas chromatography with electron capture detection (GC-ECD) and mass spectrometry (GC-MS). For the first time, the low-cost, eco-friendly GDME system was used to extract the OCPs directly from milk samples and associated with GC-ECD. Parameters that affect GDME's performance (extract volume, extraction time, and temperature) were optimized. The calibration curves of all OCPs (α- and β-hexachlorocyclohexane, lindane, hexachlorobenzene, p,p'-DDE, aldrin, dieldrin, and α-endosulfan) had coefficients of determination (r²) ranging from 0.991 to 0.995, and limits of detection (LODs) values ranging from 3.7 to 4.8 µg L^-1. This method also provided satisfactory values for precision with relative standard deviations (RSDs) lower than 10% and recoveries above 90%. As a proof-of-concept, several commercial milk samples were analyzed, aldrin was found in one of them but below the maximum residue limits.

A novel LC-MS/MS method for quantification of unstable endogenous 3,4-dihydroxyphenylacetaldehyde in rat brain after chemical derivatization

3,4-dihydroxyphenylacetaldehyde (DOPAL), a toxic intermediary metabolite of dopamine (DA), causes catecholaminergic neurodegeneration via covalent binding with functional proteins or other biomolecules. Accurate quantification of DOPAL is essential to investigate the etiological factors associated with DOPAL and the pathogenetic role of DOPAL in Parkinson's disease (PD). However, no validated quantitative methods are available. Quantification of DOPAL in biosample is challenging since it is a reactive endogenous aldehyde with poor ionization efficiency and chromatographic behavior in the LC-MS system. Here, a sensitive, simple, and robust UPLC-MS/MS method has been established and validated for the determination of DOPAL in rat brain tissue specimens. DOPAL was found to be unstable in biosample due to reactive aldehyde whereas it was stable in acidic condition. The analyte was stabilized by pH and temperature control during the sample preparation and derivatization. Then, a chemical derivatization method that can be readily performed in acidic conditions and at low temperature was employed using 2-hydrazino-4-(trifluoromethyl)-pyrimidine (HTP) to block the reactive aldehyde and improve the detection sensitivity (about 100-fold increase) and chromatographic retention. Bovine serum albumin was used as a surrogate matrix, which was validated by the parallelism assay and post-column infusion experiment. This method was fully validated and the lower limit of quantification (LLOQ) was 0.5 ng/mL. With the method, a significant increase of DOPAL level was found in striatum region of rats received 6-hydroxydopamine (6-OHDA) injection for 12 h, indicating DOPAL may play a pathogenic role in 6-OHDA-induced PD model.

Bioanalytical and Mass Spectrometric Methods for Aldehyde Profiling in Biological Fluids

Human exposure to aldehydes is implicated in multiple diseases including diabetes, cardiovascular diseases, neurodegenerative disorders (i.e., Alzheimer’s and Parkinson’s Diseases), and cancer. Because these compounds are strong electrophiles, they can react with nucleophilic sites in DNA and proteins to form reversible and irreversible modifications. These modifications, if not eliminated or repaired, can lead to alteration in cellular homeostasis, cell death and ultimately contribute to disease pathogenesis. This review provides an overview of the current knowledge of the methods and applications of aldehyde exposure measurements, with a particular focus on bioanalytical and mass spectrometric techniques, including recent advances in mass spectrometry (MS)-based profiling methods for identifying potential biomarkers of aldehyde exposure. We discuss the various derivatization reagents used to capture small polar aldehydes and methods to quantify these compounds in biological matrices. In addition, we present emerging mass spectrometry-based methods, which use high-resolution accurate mass (HR/AM) analysis for characterizing carbonyl compounds and their potential applications in molecular epidemiology studies. With the availability of diverse bioanalytical methods presented here including simple and rapid techniques allowing remote monitoring of aldehydes, real-time imaging of aldehydic load in cells, advances in MS instrumentation, high performance chromatographic separation, and improved bioinformatics tools, the data acquired enable increased sensitivity for identifying specific aldehydes and new biomarkers of aldehyde exposure. Finally, the combination of these techniques with exciting new methods for single cell analysis provides the potential for detection and profiling of aldehydes at a cellular level, opening up the opportunity to minutely dissect their roles and biological consequences in cellular metabolism and diseases pathogenesis.

Organic Analysis of Environmental Samples Using Liquid Chromatography with Diode Array and Fluorescence Detectors: An Overview

This overview is focused to provide an useful guide of the families of organic pollutants that can be determined by liquid chromatography operating in reverse phase and ultraviolet/fluorescence detection. Eight families have been classified as the main groups to be considered: carbonyls, carboxyls, aromatics, phenols, phthalates, isocyanates, pesticides and emerging. The references have been selected based on analytical methods used in the environmental field, including both the well-established procedures and those more recently developed.