Determination Of Phenolic Compounds Research Articles

Progress in MXenes and Their Composites as Electrode Materials for Electrochemical Sensing and Dye-Sensitized Solar Cells

In the present mini-review article, we have compiled the previously reported literature on the fabrication of MXenes and their hybrid composite materials based electrochemical sensors for the determination of phenolic compounds and counter electrodes for platinum (Pt)-free dye-sensitized solar cells (DSSCs). MXenes are two-dimensional (2D) materials with excellent optoelectronic and physicochemical properties. MXenes and their composite materials have been extensively used in the construction of electrochemical sensors and solar cell applications. In this paper, we have reviewed and compiled the progress in the construction of phenolic sensors based on MXenes and their composite materials. In addition, co1.unter electrodes based on MXenes and their composites have been reviewed for the development of Pt-free DSSCs. We believe that the present review article will be beneficial for the researchers working towards the development of phenolic sensors and DSSCs using MXenes and their composites as electrode materials.

Effects on the antioxidant, physicochemical, microbiological, and sensory properties of bread when supplemented with Umbu flour

Umbu fruit is rich in vitamin C and presents excellent antioxidant activity, yet its industrial processing uses only the pulp, while the residues are discarded. The residues present important nutritional properties, able to fight free radicals in the human body, and in the form of flour, might contribute reduce food insecurity and environmental waste. In view of this, our objective was to develop bread using flour from the husks and seeds of Umbu fruit as a partial replacement for wheat flour, and to assess its physical, physical-chemical, bioactive, microbiological, and sensory properties. For this, flour was prepared from Umbu wastes and used in the production of breads in concentrations of 0, 10, 20, and 30%. Respectively, the control at 0% = PC, 10% = P10, 20% = P20, and 30% = P30. Physical-chemical characterization, determination of total phenolic compounds and vitamin C, instrumental colorimetry, microbiological and sensory analyses were performed. The P20 and P30 breads presented lower humidity and pH, with higher ash, protein, lipids, acidity, total phenolic compounds, and vitamin C than the control. By instrumental color, the P20 and P30 breads were both darker and greener than the controls (PC). For microbiological analysis, all formulations were within norms established for human consumption. By sensory analysis, the breads supplemented with the Umbu residues flour were well received, yet with lower test values than the controls for all attributes and for intentions purchase. Yet in view of the above, flour made from Umbu residues remains a promising ingredient for incorporation into both breads and other bakery industry products.

Chemical characterization and biotechnological potential of Salvia rosmarinus Spenn essential oil nanoemulsions

This study aimed to determine the total phenolic compounds, evaluate the antioxidant and antiinflammatory activities of nanoemulsions (O/W) and essential oils (EOs) from Salvia rosmarinus (rosemary). The plant material was obtained in the city of São Luís (MA). The EO was obtained by the hydrodistillation technique in a modified Clevenger extractor, and the NOE’s by phase inversion. The chemical constituents of EO were determined by GC-MS. The determination of total phenolic compounds (TPC) was performed by the Folin-Ciocalteu method. The anti-inflammatory activity was performed by the method of protein denaturation, and the antioxidant activity was performed by the spectrophotometric method of scavenging hydroxyl radicals. The GC-MS allowed quantifying 1,8-cineol (30.22%), α-pinene (22.14%), camphor (18.33%), and camphene (10.36%) as major components of the EO. The TPC of the EO was quantified at 26.74 mg EAT g-1 and the refractive index at 1.466 nD 25°. In the antioxidant activity test, an EC50 of 80.33 mgL-1 was obtained for the EO and from 19.56 to 408.85 mg L-1 for the nanoemulsions. In the anti-inflammatory activity assay, an EC50 of 62.46 mgL-1 was obtained for EO and 64.96 to 4220.25 mg L-1 for NOE’s. Finally, the pharmacological activities tested showed efficient values for EC50, therefore being considered active. This activity is attributed to the chemical compounds present, thus encouraging studies with this species aiming at its potential application in a formulated bioproduct.

Greener method proposal for the determination of phenolic compounds and coumarins in aged sugarcane spirits using green bio-based solvents in HPLC-DAD-FLD system

High Performance Liquid Chromatography (HPLC) has been the most used analytical technique for analyzing phenolic compounds and coumarins in aged sugarcane spirit samples. It requires a significant amount of organic solvents, often toxic, as the mobile phase. The use of green bio-based solvents is a good alternative in the implementing more eco-friendly methods. Therefore, this work aims to propose a greener chromatographic method for the determination of phenolic compounds and coumarins in sugarcane spirit samples aged in different woods, using bio-based organic solvents (ethanol and acetic acid) in HPLC system with diode array and fluorescence detectors. Different metric tools (AGREE, ComplexMoGAPI, BAGI and Analytical Eco-scale) were used to evaluate the greenness of the analytical method. The proposed method was rigorously validated: linearity (R2 ≥ 0.9901); LOD (0.05 to 0.55 mg l-1); LOQ (0.25 to 5.00 mg l-1); precision (0.13 % ≤ RSD ≤ 18.6 %). The concentrations of total phenolic compounds and coumarins were up to 7.22 mg l-1. The sugarcane spirit aged in umburana presented the highest concentration of total phenolic compounds and coumarins with emphasis on trans-cinnamic acid (4.74 ± 0.01 mg l-1) and catechin (1.22 ± 0.02 mg l-1). All samples presented coumarin concentrations (<5.00 mg l-1) within the limit acceptable by legislation (10 mg l-1). The AGREE score (0.72) showed that the proposed method was greener and sustainable compared to other methods. The application of new mobile phase using green bio-based solvents proved to be advantageous from a Green Analytical Chemistry point of view.

Sustainable approaches to analyzing phenolic compounds: a green chemistry perspective.

Innovative and eco-friendly methodologies for the determination of phenolic compounds, showing a paradigm shift in analytical chemistry toward sustainability. Phenolic compounds, valued for their diverse health benefits, have historically been analyzed using methods that often involve hazardous solvents and energy-intensive processes. This review focuses on green analytical chemistry principles, emphasizing sustainability, reduced environmental impact, and analytical efficiency. The use of DES, specifically Ch: Chl-based DES, emerges as a prominent green alternative for extracting phenolic compounds from various sources. The integration of UAE with DES enhances extraction efficiency, contributing to a more sustainable analytical approach. Furthermore, the review highlights the significance of DLLME and SPME in reducing solvent consumption and simplifying extraction procedures. These techniques exemplify the commitment to making phenolic compound analysis environmentally friendly. The incorporation of portable measurement tools, such as smartphones, into analytical methodologies is a notable aspect discussed in the review. Techniques like UA-DLLME leverage portable devices, making phenolic compound determination more accessible and versatile. Anticipating the future, the review foresees ongoing advancements in sustainable analytical approaches, driven by collaborative efforts across diverse disciplines. Novel solvents, extraction techniques, and portable measurement methods are expected to play pivotal roles in the continuous evolution of green analytical methodologies for the analysis of phenolic compounds. The review encapsulates a transformative journey toward environmentally responsible and efficient analytical practices, paving the way for further research and application in diverse analytical settings.

3-Methyl Thiophene-Modified Boron-Doped Diamond (BDD) Electrodes as Efficient Catalysts for Phenol Detection-A Case Study for the Detection of Gallic Acid in Three Specific Tea Types.

Polymer modification has been established as a cost-effective, simple, in situ method for overcoming some of the inherent disadvantages of boron-doped diamond (BDD) electrodes, and its application has been extended to reliable, low-cost environmental monitoring solutions. The present review focuses on modifying BDD electrodes with semi-conductive polymers acting as redox mediators. This article reports on the development of a 3-methyl thiophene-modified boron-doped diamond (BDD/P3MT) sensor for the electrochemical determination of total phenolic compounds (TPCs) in tea samples, using gallic acid (GA) as a marker. GA is a significant polyphenol with various biological activities, making its quantification crucial. Thus, a simple, fast, and sensitive GA sensor was fabricated using the electroanalytical square wave voltammetry (SWV) technique. The sensor utilizes a semi-conductive polymer, 3-methyl thiophene, as a redox mediator to enhance BDD's sensitivity and selectivity. Electrochemical synthesis was used for polymer deposition, allowing for greater purity and avoiding solubility problems. The BDD/P3MT sensor exhibits good electrochemical properties, including rapid charge transfer and a large electrochemical area, enabling GA detection with a limit of detection of 11 mg/L. The sensor's response was correlated with TPCs measured by the Folin-Ciocalteu method. Square wave voltammetry (SWV) showed a good linear relationship between peak currents and GA concentrations in a wide linear range of 3-71 mg/L under optimal conditions. The BDD/P3MT sensor accurately measured TPCs in green tea, rooibos tea, and black tea samples, with green tea exhibiting the highest TPC levels. The results demonstrate the potential of the modified BDD electrode for the rapid and accurate detection of phenolic compounds in tea, with implications for quality control and antioxidant activity assessments. The prolific publications of the past decade have established BDD electrodes as robust BDD sensors for quantifying polyphenols. Fruits, vegetables, nuts, plant-derived beverages such as tea and wine, traditional Eastern remedies and various herbal nutritional supplements contain phenolic chemicals. The safety concerns of contaminated food intake are significant health concerns worldwide, as there exists a critical nexus between food safety, nutrition, and food security. It has been well established that green tea polyphenol consumption promotes positive health effects. Despite their potential benefits, consuming high amounts of these polyphenols has sparked debate due to concerns over potential negative consequences.

Chemical characterization and biotechnological potential of Salvia rosmarinus Spenn essential oil nanoemulsions

This study aimed to determine the total phenolic compounds, evaluate the antioxidant and anti-inflammatory activities of nanoemulsions (O/W) and essential oils (EOs) from Salvia rosmarinus (rosemary). The plant material was obtained in the city of São Luís (MA). The EO was obtained by the hydrodistillation technique in a modified Clevenger extractor and the NOE's by phase inversion. The chemical constituents of EO were determined by GC-MS. The determination of total phenolic compounds (TPC) was performed by the Folin-Ciocalteu method. The anti-inflammatory activity was performed by the method of protein denaturation and the antioxidant activity by the spectrophotometric method of scavenging hydroxyl radicals. The GC-MS allowed quantifying 1,8-cineol (30.22%), α-pinene (22.14%), camphor (18.33%) and camphene (10.36%) as major components of the EO. The TPC of the EO was quantified at 26.74 mg EAT g-1 and the refractive index at 1.466 nD 25°. In the antioxidant activity test, an EC50 of 80.33 mgL-1 was obtained for the EO and from 19.56 to 408.85 mg L-1 for the nanoemulsions. In the anti-inflammatory activity assay, an EC50 of 62.46 mgL-1 was obtained for EO and 64.96 to 4220.25 mg L-1 for NOE's. Finally, the pharmacological activities tested showed efficient values ​​for EC50, therefore considered active. This activity is attributed to its chemical compounds present, thus encouraging studies with this species aiming at its potential application in a formulated bioproduct.

Enhancing Vascular Health and Lowering Blood Pressure in Spontaneously Hypertensive Rats through Syrah Grape (Vitis vinifera) Pomace: The Role of Phenolic Compounds.

The beneficial properties of wine by-products include actions that help prevent and treat cardiovascular conditions such as hypertension, primarily due to their antioxidant effects. Novel pharmacotherapies are being developed to treat arterial hypertension, including investigations into natural products exhibiting biological activity, necessitating rigorous evaluation of their efficacy and safety. This study aimed to identify and quantify phenolic compounds in Syrah (Vitis vinifera) grapes grown in the Brazilian Cerrado and their presence in winemaking by-products. It also examined the effects of grape pomace on blood pressure. Fresh grapes, pomace, and lees, were subjected to spectrophotometric determination of total phenolic compounds, followed by identification and quantification using HPLC-DAD-ESI-MSn. Normotensive male rats (Wistar) and spontaneously hypertensive rats (SHR) received grape pomace-enriched (150 or 300 mg/kg/day, 14 days) or standard chow. Indirect arterial pressure was assessed, while vascular reactivity was evaluated in mesenteric resistance arteries. Pomace samples exhibited higher total phenolic compound concentrations than grapes or lees. Seven derivatives of hydroxycinnamic acids and twenty-one flavonols were identified. Quercetin-3-glucoside and ethyl caffeate were the most abundant phenolic compounds. Grape pomace-enriched chow demonstrated a dose-dependent hypotensive effect in rats. the abundance of flavonols and hydroxycinnamic acids, combined with their hypotensive effects, underscores the therapeutic potential of fine wine-making by-products produced in the Brazilian Cerrado.

Ultrasound-assisted extraction, optimisation using response surface methodology and HPLC-DAD phenolic compounds quantification from Passiflora edulis S. peels cultivated in Tunisia

A new ultrasound-assisted extraction method was developed for the determination of phenolic compounds extracted from Passiflora edulis Sims peels cultivated in Tunisia. Several extraction variables including: extraction time, temperature, liquid/solid ratio and pH have been studied using response surface methodology. The extraction efficiency was evaluated by measuring the total phenolics; flavonoids and antioxidants content. The highest values of the studied response were observed after 9.78 min at 49.64 °C in a liquid-to-solid ratio 22.07 ml/g and in pH (5.54). The individual phenolic compounds content of the optimum extract peels of the Passiflora edulis Sims have been analysed using HPLC-DAD. The results revealed the presence of gallic followed by caffeic acids, while the apigenin-7-glucoside and rutin have been quantified as the abundant flavonoid compounds (0.653 and 0.488 mg/ml, respectively). This green procedure should be a promising option to guide industrial design for the production of phenolic-rich plant extracts.

Development and validation of a UHPLC-ESI-MS/MS method for the simultaneous determination of organic acids and phenolic compounds in Filipendula vulgaris, Polygonum divaricatum, Hypericum linarioides, and Rheum ribes

This research focused on investigating biologically active and pharmaceutically important phytochemicals using reliable and reproducible analytical techniques specifically designed for traditional medicinal plants. Considering the complex chemical diversity present in plant extracts, reliable identification methods are crucial. The goal of this study was to develop and validate a robust UHPLC-ESI-MS/MS method for the qualitative and quantitative analysis of organic acids (OAs) and phenolic compounds (PCs). With gradient elution of water containing 0.1 % formic acid and acetonitrile containing 0.1 % formic acid as the mobile phase, OAs and PCs were separated chromatographically on a C18 reversed-phase column. Through the use of an electrospray ionization source operating in negative ionization mode, these compounds were identified on a triple quadrupole tandem mass spectrometer. The validation results clearly indicate that the method exhibited linearity with a squared correlation coefficient (R2 ≥ 0.9986), demonstrating sensitivity (LOQ: 1.08 µg/L-10.79 µg/L), precision (RSD%≤2.73), and trueness (RE% ≤ 1.53) for the OAs and PCs found in the plants. The developed UHPLC-ESI-MS/MS method was successfully applied to the qualitative and quantitative analysis of OAs and PCs in Turkish plants, which are commonly used in traditional medicine. Our study identified a total of 12 OAs and PCs in F. vulgaris, 12 in P. divaricatum, 9 in H. linarioides, and 11 in R. ribes. In particular, gallic acid had the highest content in F. vulgaris (925.67 µg/g extract) and R. ribes (1358.78 µg/g extract), while H. linarioides (730.66 µg/g extract) and P. divaricatum (4003.02 µg/g extract) had relatively high levels of quinic acid. In conclusion, the developed UHPLC-ESI-MS/MS method allows the simultaneous analysis and quantification of 2 OAs and 33 PCs in plants and proves to be a valuable tool for evaluating the efficacy of traditional medicinal plants.

An efficient determination of phenolic compounds by HPLC-DAD and their bioactivity assay from aerial parts of Eucalyptus tereticornis plant

An efficient determination of phenolic compounds by HPLC-DAD and their bioactivity assay from aerial parts of Eucalyptus tereticornis plant

Derivative Spectrophotometric Methods for Simultaneous Determination of Quercetin and Gentisic acid in Capparis spinosa L.

الشفلح هو أحدی النباتات الطبية الذي یستخدم في الطب التقليدي و یتضمن المواد الكيميائية النباتية العديدة مثل المركبات بوليفينولیة. تعتبر كلتا المركبتين، كویرستین وحامض الجینتسیك، کمركب فينولية مهمة اللتان توجدان في النباتات ولهما الخصائص الطبية الکثیرة مثل مضاد الالتهابات، مضاد الميكروبات، مضاد الأكسدة ومضاد للسرطان. لم يتم التحقق بعد من تحديد كلا المركبين معًا في مزیج ثنائي باستخدام طرق القياس الطيفي. في هذه الدراسة، تم تطوير طريقتين طيفيتين مشتقتين بسيطتين سريعتين و دقيقتين لاستخدامهما للتقدير الكمي الآنی لمادة كویرستین وحامض الجینتسیك في المزيج الثنائية وخلاصة أوراق الشفلح. الطريقة الأولی تعتمد على استخدام طریق العبور الصفري (المشتق الأول والرابع) ، بينما الطريقة الثانية هي المشتق الأول لأطياف النسبة. الخطية لمنحنيات المعايرة لكلتا الطريقتين الطيفية المشتقة يتراوح تركيزهما بين 2.0-30 ميكروغرام / مل و 4.0-80 ميكروغرام / مل لكویرستین وحامض الجینتسیك، على التوالي، في حين تراوحت نسب الاسترداد من 94.06٪ الی 105.98٪ (كویرستین) و 94.29٪ الی 113.37٪ (حمض الجینتسیك). تم استخدام الطرق المطورة بشكل فعال في التقدیر الكمي لكل من المركبات الفينولية في أوراق الشفلح..

Histidine–cysteine–copper hybrid nanoflowers as active site-inspired laccase mimics for the colorimetric detection of phenolic compounds in PDMS microfluidic devices

Although laccases are essential multicopper oxidases in biosensing and bioremediation, their widespread use is hindered by issues such as instability and high cost. In this study, drawing inspiration from the active site structure of laccase, we developed hybrid nanoflowers through the coordination of copper ions with histidine-cysteine dipeptides (HC–Cu NFs) as highly robust laccase-mimicking nanozymes. The HC–Cu NFs possessed higher laccase-like activity compared to free laccase, yielding an approximately five-fold higher Vmax with a similar Km at the same mass concentration. Additionally, HC–Cu NFs exhibited exceptional stability across diverse environments, including a broad range of pH, temperature, salinity, and extended storage periods. Notably, HC-Cu NFs catalyzed the decolorization of phenolic dyes more rapidly than natural laccase. Utilizing these beneficial features, HC–Cu NFs were incorporated in a polydimethylsiloxane-based microfluidic device, enabling the on-site colorimetric determination of phenolic compounds, such as p-aminophenol, catechol, and hydroquinone, with outstanding sensitivity. By injecting only 20 μL of the sample solution through the inlet of the device, the sample solution rapidly moves to the detection zones where the HC-Cu NFs are retained, followed by catalytic oxidation to further react with 4-aminoantipyrine to produce a colored adduct. Using the microfluidic device, the target phenolic compounds were successfully determined within 20 min at ambient conditions using an image acquired with a smartphone with the ImageJ software. This study unequivocally demonstrates that active site-mimicking dipeptide-incorporated hybrid nanoflowers have the potential to serve as nanozymes, to replace natural laccase. This lays the groundwork for the further advancement of hybrid nanoflower-type nanozymes and their applications, particularly in point-of-care testing environments.

Two-dimensional metal-organic framework nanozyme-mediated portable paper-based analytical device for dichlorophen assay

The metal-organic frameworks (MOFs) nanozyme-mediated paper-based analytical devices (PADs) have shown great potential in portable visual determination of phenolic compounds in the environment. However, most MOF nanozymes suffer from poor dispersibility and block-like structure, which often prompts deposition and results in diminished enzymatic activity, severely hindering their environmental applications. Here, we proposed colorimetric PADs for the visual detection of dichlorophen (Dcp) based on its significant inhibitory effect on the two-dimensional (2D) MOF nanozyme activity. Specifically, we synthesized a 2D Cu TCPP (Fe) (defined as 2D-CTF) MOF nanozyme exhibiting excellent dispersibility and remarkable peroxidase-like (POD-like) activity, which could catalyze the oxidation and subsequent color change of 3,3′,5,5′-tetramethylbenzidine even under neutral conditions. Notably, the POD-like activity of 2D-CTF demonstrated a unique response to Dcp because of the occupation of Fe–N4 active sites on the 2D-CTF. This property enables the use of 2D-CTF as a highly efficient catalyst to develop colorimetric PADs for naked-eye and portable detection of Dcp. We believe that the proposed colorimetric PADs offer an efficient method for Dcp assay and open fresh avenues for the advancement of colorimetric sensors for analyzing of phenolic toxic substances in real samples.

Ultrasound-assisted extraction of shikimic acid and determination of total phenolic compounds in water hyacinth: Grey-based Taguchi optimization

Shikimic acid (SA) is a precursor for formulating the antiviral drug oseltamivir phosphate (Tamiflu®). Ultrasound-assisted extraction was employed to extract shikimic acid using water as a solvent and to determine total phenolic compounds (TPC) from water hyacinth. Grey-based Taguchi optimization was used to optimize the yield of shikimic acid and TPC by varying four distinct parameters. The best results for the yield of SA, i.e., 3.3 % (20 min time, 20 mL water volume, 60 % amplitude, and 40 % pulse ratio) and 3.2 % (30 min time, 20 mL solvent volume, 40 % amplitude, and 40 % pulse ratio) were observed using single and multi-response optimization, respectively for the stem. The best results for TPC, i.e., 12.24 mg GAE/ g biomass (20 min time, 40 mL solvent volume, 40 % amplitude, and 30 % pulse ratio) and 10.53 mg GAE/ g biomass (20 min time, 20 mL solvent volume, 50 % amplitude, 40 % pulse ratio) were obtained using single and multi-response optimization, respectively for leaves. The extraction was also performed for a whole plant (without segregation), and 1.66 % yield of SA (20 min time, 20 mL solvent volume, 50 % amplitude, 40 % pulse ratio) and TPC value of 8.84 mg GAE/ g biomass (40 min time, 30 mL solvent volume, 40 % amplitude, 40 % pulse ratio) were obtained.

Separation and determination of phenolic compounds using novel deep eutectic solvent-in-water microemulsion electrokinetic chromatography

BackgroundMicroemulsion electrokinetic chromatography (MEEKC) is a mode of capillary electrophoresis with a wide range of applications in which microemulsion is utilized as background electrolyte to achieve the separation of analytes. Microemulsions are composed of oil droplets, aqueous buffer, surfactant, and co-surfactant. Currently, conventional organic reagents act as the most commonly used oil phase in microemulsions, which are unfriendly to the environment. Recently, deep eutectic solvent (DES) has become a new type of eco-friendly solvent due to its non-toxicity. Therefore, it is of great value to establish a new MEEKC method by replacing conventional organic reagents as the oil phase with DES. ResultsThe novel DES/W MEEKC method was established for phenolic compounds in Senecio scandens samples. Single-factor experiments and response surface methodology were performed to systematically optimize the crucial parameters for the method, including the type and content of the oil phase, surfactant content, concentration of borax buffer, and pH of the background solution.Under the optimized conditions, satisfactory regression curves were established for all standard analytes with correlation coefficients ≥0.9990. The method featured high sensitivity and favorable accuracy, with the instrumental detection limit in the range of 0.22–1.04 μg/mL, and intraday and interday precision for migration time expressed as relative standard deviations of 0.18–0.82% and 1.25–2.50%, respectively. The DES/W MEEKC method was successfully applied to Senecio scandens with good recoveries of 87.72–106.99%. In conclusion, the newly established DES/W MEEKC method is highly efficient, green and environmentally friendly. SignificanceDES is considered a green and efficient solvent. The DES/W MEEKC method is highly efficient and environmentally friendly. Actually, the method provides a novel and effective analytical tool for the simultaneous separation and determination of multiple phenolic compounds, especially in complex plant matrices. In the future, the DES/W MEEKC method still has the prospect of being widely used in the separation of other complex phytochemicals.

Salt-assisted liquid-liquid extraction and on-column concentration for chromatographic determination of phenolic compounds in beer

Salt-assisted liquid-liquid extraction (SALLE) and on-column concentration were evaluated to simplify the chromatographic determination of phenolic compounds in beer. Resveratrol, flavonoids (quercetin and kaempferol), and phenolic acids (caffeic, p-coumaric, and trans-ferulic acids) were used as model compounds based on their concentrations reported in craft beers. SALLE with acetonitrile was effective for sample cleanup, with recoveries ranging from 84 % to 112 %. The on-column concentration was carried out in high performance liquid chromatography by starting the gradient elution with acidified water (sample carrier stream) in a reversed-phase mode. Consequently, the analytes were retained in a narrow band, and highly polar/ionic potentially interfering species were flushed from the column. The effectiveness of the approach was demonstrated by linear correlations between the peak areas and the injected volumes from 10 to 200 µL (r ≥ 0.999), without significant variations in peak width (< 10 %), retention times (< 0.7 %), and peak symmetry (tailing factors within the range of 0.8–1.1). For all analytes, a linear response was achieved from 100 to 1000 µg L−1 (r > 0.999), with limits of detection within the range of 9–82 µg L−1. The approach was also effective for on-column concentrations of resveratrol, quercetin, and kaempferol in sequential injection chromatography (SIC), with injected volumes up to 750 µL and linear responses within 100–1000 µg L−1 (r > 0.997). The proposal reduced consumption of organic solvents (with only 770 µL required per determination in SIC) and avoided solid-phase extraction cartridges for analyte preconcentration.

Exploring the potential of phenolic and antioxidant compounds in new Rosaceae fruits.

Rosaceae fruits have been used in traditional medicine for the prevention and treatment of diseases. However, these fruits have not extensively been studied regarding their phenolic composition. Thus, this research focuses on the determination of phenolic compounds by high-performance liquid chromatography electrospray ionization time-of-flight mass spectrometry, flavan-3-ols by high-performance liquid chromatography with fluorescence detection, and the antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and ferric reducing antioxidant power of the fruits of five species of genera Crataegus and Sorbus (Rosaceae). We found a total of 71 phenolic compounds from which 30 were identified in these berries for the first time. Crataegus monogyna and Crataegus laciniata revealed higher total phenolic and flavan-3-ol contents than the other species and the highest antioxidant activities. Therefore, the fruits evaluated have demonstrated to be important sources of bioactive compounds with huge potential for being used in nutraceutical or food scopes. Additional studies could be needed to evaluate the influence of the different production areas on the phenolic content. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Disposable biosensor based on nanodiamond particles, ionic liquid and poly-l-lysine for determination of phenolic compounds

This study describes the development of a highly sensitive amperometric biosensor for the analysis of phenolic compounds such as catechol. The biosensor architecture is based on the immobilization of tyrosinase (Tyr) on a screen-printed carbon electrode (SPE) modified with nanodiamond particles (ND), 1-butyl-3-methylimidazolium hexafluorophosphate (IL) and poly-l-lysine (PLL). Surface morphologies of the electrodes during the modification process were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical characteristics of the modified electrodes. Owing to the synergistic effect of the modification materials, the Tyr/PLL/ND−IL/SPE exhibited high sensitivity (328.2 μA mM−1) towards catechol with a wide linear range (5.0 × 10−8 – 1.2 × 10−5 M) and low detection limit (1.1 × 10−8 M). Furthermore, the method demonstrated good reproducibility and stability. The amperometric response of the biosensor towards other phenolic compounds such as bisphenol A, phenol, p-nitrophenol, m-cresol, p-cresol and o-cresol was also investigated. The analytical applicability of the biosensor was tested by the analysis of catechol in tap water. The results of the tap water analysis showed that the Tyr/PLL/ND−IL/SPE can be used as a practical and effective method for catechol determination.

Determination of phenolic compounds in water using a multivariate statistical analysis method combined with three-dimensional fluorescence spectroscopy.

Phenolic compounds are toxic chemical pollutants present in water. Three-dimensional fluorescence spectroscopy analysis is an effective and rapid method for real-time phenol monitoring in aquatic environments. However, similar chemical structures of phenols result in highly overlapping three-dimensional fluorescence spectra. Therefore, it is extremely difficult to analyze and quantify the concentration of components in a mixture system that includes two or more phenolic compounds. In this article, we study the mixed phenol system containing phenol, o-cresol, p-cresol, m-cresol, catechol, and resorcinol combined with excitation-emission matrix (EEM) fluorescence data. A multivariate statistical method called best linear unbiased prediction (BLUP) is proposed to analyze the spectra with the aim to achieve quantitative results and a trilinear decomposition algorithm called parallel factor analysis (PARAFAC) was used for comparison. Two experiments with different calibration samples were set to validate the effectiveness of BLUP through recovery, ARecovery (Average Recovery), AREP (Average Relative Error of Prediction), and RMSE (Root Mean Square Error). Overall, the average recovery of each component in experiment 1 and experiment 2 ranged from 95.91% to 111.62% and 82.91% to 129.02%, respectively. Based on the results of the experiments, the concentration of phenolic compounds in water can be quantitatively determined by combining three-dimensional fluorescence spectroscopy with the BLUP method.