Disposable Stochastic Miniplatforms for Simultaneous Recognition and Determination of Vitamins B5, B7, and B9 in Food and Pharmaceutical Compounds.

Vitamins are essential for supporting daily physiological functions and are crucial for metabolic processes, including preventing vascular events and delaying the progression of diabetic nephropathy. The specific assessment of food and pharmaceutical compound quality requires the highly sensitive evaluation of vitamins B5, B7, and B9. Therefore, it is necessary to have a fast screening method for multivitamin tablets, pharmaceutical tablets, water, food, including raw egg yolk, and biological fluids, including urine, in order to ensure the precise identification and measurement of vitamins B5, B7, and B9. This paper introduces a novel disposable stochastic miniplatform that utilizes an incorporated 2D stochastic sensor to be able to simultaneously assay the three vitamins. Cobalt-phthalocyanine was used to modify the carbon film of the 2D sensor. High sensitivities (of 102-108 s-1 g-1 mL magnitude order) and low detection limits (of pg mL-1 magnitude order) were recorded for the disposable stochastic miniplatforms. The validation procedure involved the utilization of pharmaceutical tablets, supplement tablets, water samples, food samples, including raw egg yolk, and biological samples, specifically urine. The disposable stochastic miniplatforms demonstrate cost-effectiveness and suitability for the fast screening tests, with a time frame of 6 min, across a range of samples, a capacity of over 150 measurements, and an endurance of up to one month. Recovery values higher than 94.00% with RSD (%) values lower than 1.00 were recorded.

Stochastic platform based on calix[6]arene and TiO2-modified reduced graphene oxide electrode for on-site determination of nonivamide in pharmaceutical and water samples.

Using a detection platform based on an integrated sensor constructed by modifying TiO2 and reduced graphene oxide paste with calix[6]arene, a novel stochastic approach for both quantitative and qualitative analysis of nonivamide in pharmaceuticals and water samples has been developed. A wide analytical range of 1.00 × 10-18 to 1.00 × 10-1 mol L-1 was obtained with the stochastic detection platform for nonivamide determination. A very low limit of quantification of 1.00 × 10-18 mol L-1 was reached for this analyte. The platform was successfully tested on real samples, respectively, on topical pharmaceutical dosage form and surface water samples. The samples were analyzed without pretreatment in the case of pharmaceutical ointment or under minimal preliminary processing for surface waters proving a facile, rapid, and reliable method. Moreover, being portable, the developed detection platform is adequate for on-site analysis in various sample matrices.

Electrochemical platform based on molecularly imprinted polymer with zinc oxide nanoparticles and multiwalled carbon nanotubes modified screen-printed carbon electrode for amaranth determination.

A novel electrochemical platform for amaranth determination has been developed using a rapid, easy, inexpensive, and portable molecularly imprinted polymer technique. The MIP platform was fabricated by electropolymerizing melamine as monomer in the presence of amaranth as template on the surface of ZnO-MWCNT/SPCE. Then, amaranth was completely eluted, leaving imprinted cavities in the polymeric film that could effectively recognize amaranth in solution. The electrochemical platform based on a molecularly imprinted polymelamine was analyzed by scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Under optimum conditions, the developed MIP/ZnO-MWCNT/SPCE platform can be properly used for amaranth determination, with high sensitivity of 96.2 µA µM cm-2, two linear concentration ranges (0.01 to 1 µM and 1 to 1000 µM) and a low limit of detection of 0.003 µM. The anodic peak potential of amaranth was found to be 0.73 V. Additionally, the polymelamine MIP films specifically recognize amaranth molecules, making it possible to detect amaranth in a complex solution with high selectivity, excellent repeatability, reproducibility, and stability. The MIP/ZnO-MWCNT modified screen-printed carbon electrode was successfully applied to determine amaranth in pharmaceutical and water samples, with recovery values ranging from 99.7 to 102% and RSD% values less than 3.2%.

Simultaneous determination of anthracene and phenanthrene using a poly-alizarin red S/carbon paste electrode.

A polymer-based carbon paste electrode was constructed by electropolymerized Alizarin Red S (ARS) film on the carbon paste electrode (CPE) surface. The electrochemical properties of poly-ARS/CPE were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy (SEM) was utilized for electrode characterization. The electropolymerization cycles for the construction of the sensor and the supporting electrolyte were optimized. With 0.1 M LiClO4 as a supporting electrolyte, poly-ARS/CPE was able to generate oxidation peaks for anthracene (ANT) and phenanthrene (PHE), that were clearly defined and easily distinguished from one to another when operating in square wave voltammetry (SWV). In the simultaneous detection the linear ranges of ANT and PHE were within 80-1000 µM, with detection limits of 24 µM. The variation of peak parameters with scan rate was investigated to determine the nature of electrooxidation and the number of electrons involved in the electrode process. Poly-ARS/CPE was successfully utilized for the detection of ANT and PHE in different water samples and the obtained results suggested the selectivity, stability and reproducibility of the modified electrode.

N-Methylfulleropyrrolidine-Based Multimode Sensor for Determination of Butoconazole Nitrate.

A multimode sensor (a sensor responding simultaneously to more than one mode, e.g., stochastic mode, amperometric mode, voltammetric mode) based on graphite paste modified with N-methylfulleropyrrolidine was proposed for the determination of butoconazole nitrate in its pharmaceutical formulation. The stochastic mode and square wave voltammetry mode were applied for the determinations. Both the stochastic mode and square wave voltammetry mode were applied for a qualitative and quantitative assay of butoconazole nitrate. The sensor can be used between 1.68 × 10-6 and 1.68 × 104 µmol L-1 when the stochastic mode is used and between 0.168 and 16.80 µmol L-1 when the square wave voltammetry mode is used. The multimode sensor was reliably used for the determination of butoconazole nitrate in its pharmaceutical formulation, Gynofort cream, the recorded recoveries being higher than 99.00%, with RSD (%) values of lower than 2.00%.

Sodium Metabisulfite in Food and Biological Samples: A Rapid and Ultra-Sensitive Electrochemical Detection Method.

The primary benefit of using sulfites as a food additive is their antimicrobial and antioxidant properties, which stop fungi and bacteria from growing in a variety of foods. The application of analytical methods is necessary to ensure food quality control related to the presence of sulfites in a variety of foods. For the detection of sodium metabisulfite in food and urine samples, two sensors based on reduced graphene oxide doped with Pd paste and modified with 5,10,15,20-tetraphenyl-21H,23H-porphyrin and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin were proposed. The new sensors were evaluated and characterized using square wave voltammetry. The response characteristics showed that the detection limits for the sensors were 3.0 × 10-12 mol L-1 for TPP/rGO@Pd0 based sensors and 3.0 × 10-11 mol L-1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors while the quantification limits were 1.0 × 10-11 mol L-1 for TPP/rGO@Pd0 based sensors and 1.0 × 10-10 mol L-1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors. The sensors can be used to determine sodium metabisulfite in a concentration range between 1.0 × 10-11 and 1.0 × 10-7 mol L-1 for TPP/rGO@Pd0 based sensors and between 1.0 × 10-10 mol L-1 and 1.0 × 10-6 mol L-1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors. A comparison between the proposed methods' results and other analytical applications is also presented.

Carbon Nanopowder-Based Stochastic Sensor for Ultrasensitive Assay of CA 15-3, CEA and HER2 in Whole Blood.

Two microsensors obtained by the physical immobilization of 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP) and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin (Fe(TPFPP)Cl) in carbon nanopowder decorated with gold nanoparticles (AuNp) were designed, characterized, validated and used for the molecular recognition and simultaneous ultrasensitive determination of CEA, CA15-3 and HER2 in whole blood. High sensitivities were recorded for both microsensors. Low limits of quantification were recorded for all biomarkers: CEA (12.8 pg mL-1 by using Fe(TPFPP)Cl/AuNp, and 190 fg mL-1 by using TPP/AuNp), CA 15-3 (100 fU mL-1 for both microsensors) and HER2 (3.9 fg mL-1 by using Fe(TPFPP)Cl/AuNp, and 35 fg mL-1 by using TPP/AuNp). A very good correlation between the results obtained using the proposed microsensors and ELISA, certified by the Student t-test, proves that the screening test can be used for ultrasensitive assays of the three biomarkers in whole blood.

Rapid and sensitive electrochemical determination of tartrazine in commercial food samples using IL/AuTiO2/GO composite modified carbon paste electrode.

A novel electrochemical sensor based on the modification of carbon paste electrode with an ionic liquid (1-butyl-2,3-dimethylimidazolium tetrafluoroborate) and AuTiO2/GO composite (IL/AuTiO2/GO/CPE) was developed for rapid and sensitive determination of tartrazine by differential pulse voltammetry. Under the optimum experimental conditions, the peak current was linear to concentration of tartrazine in the ranges of 1-400 µmol L-1 and 400-1000 µmol L-1, with sensitivities of 0.008 µA µmol L-1 and 0.002 µA µmol L-1, respectively, and with a limit of detection of 0.33 µmol L-1 (S/N = 3). To demonstrate the performance of the method, the reproducibility was studied and the obtained values of RSD% were 2.72%. The method was applied to the sensitive determination of tartrazine in isotonic drink, mustard and yellow egg dye samples with recovery rates between 98.55% and 103.62%.

Fast screening method for early diagnostic of gastric cancer based on utilization of a chitosan - S-doped graphene - based needle stochastic sensors.

Needle stochastic sensors were developed for the assay of carbohydrate antigen 19-9 (CA 19-9) and carcinoembryonic antigen (CEA) in different biological samples (e.g., whole blood, tissues, urine, and saliva). Sulfur doped graphene powders were modified with chitosan; paraffin oil was added to form a homogeneous paste that was used as active side of the stochastic sensors. High sensitivities and low limits of determination were achieved for the assay of CA19-9 and CEA in biological samples. The validation of the proposed screening method (which is utilizing the stochastic sensors as screening tools) was made by using real biological samples obtained from confirmed patients with gastric cancer; very good correlations for the concentrations of CEA and CA19-9 were obtained using the needle stochastic sensors.

Recent Trends in Ibuprofen and Ketoprofen Electrochemical Quantification - A Review.

Non-steroidal anti-inflammatory drugs are intensively manufactured, used, and regulated. However, these compounds incur toxic effects on gastrointestinal, cardiovascular, and renal systems when administered in high doses for extended periods. Additionally, once these drugs reach the ecosystems through various pathways, they become environmental contaminants and raise ecological concerns. Traditional detection methods proposed for non-steroidal anti-inflammatory drugs detection encompass certain limitations. In this context, the need for simple, cost-effective, sensitive, and selective detection methods that could improve the quality of analysis led the attention of the scientific community toward electrochemical sensors. The lowest limit of detection of ibuprofen (33.33 × 10-12 µmol L-1) was recorded for a sensor based on ibuprofen specific aptamer bound with nitrogen-doped graphene quantum dots and gold nanoparticles nanocomposite modified glassy carbon electrode using differential pulse voltammetry, while the lowest limit of detection reported for ketoprofen was 0.11 µmol L-1 when differential pulse voltammetry was used. This review focuses on the construction, analytical performances, and applicability of electrochemical sensors developed for ibuprofen and ketoprofen determination. This work covers 24 articles published between 2016 and 2022.

Mini-Review: Electrochemical Sensors Used for the Determination of Water- and Fat-Soluble Vitamins: B, D, K.

Vitamins are one of the most essential organic compounds that are necessary for the human body, in order to develop and grow in a healthy way. The aim of this mini-review is to bring together a series of electrochemical sensors (voltametric and amperometric) developed for the determination of vitamins from the families of B, D and K in biological, pharmaceutical or food-related samples. For this mini-review, 16 articles published between 2016 and 2021 were taken into consideration.

Smart Portable Device Based on the Utilization of a 2D Disposable Paper Stochastic Sensor for Fast Ultrasensitive Screening of Food Samples for Bisphenols.

Since the determination of the high toxicity of bisphenol A, alternative structures for bisphenols have been synthesized, resulting in bisphenols C, E, F, S, and Z. These bisphenols have replaced bisphenol A in plastic bottles, toys, and cans used for preserving food. Later, the toxicity and negative effects of all of these bisphenols on people's health were proven. Therefore, there is a need for a fast ultrasensitive screening method that is able to detect the presence of these bisphenols in any condition directly from food samples. This paper presented a disposable device based on the utilization of a 2D disposable paper stochastic sensor for the fast ultrasensitive screening of food samples for bisphenols A, C, E, F, S, and Z. The 2D disposable sensor was obtained by the deposition of graphene and silver nanolayers on paper using cold plasma. Furthermore, the active side of the sensor was modified using 2,3,7,8,12,13,17,18-octaethyl-21H,23H Mn porphyrin. The limits of quantification of these bisphenols were 1 fmol L-1 for bisphenols C and E, 10 fmol L-1 for bisphenols A and F, 10 pmol L-1 for bisphenol S, and 1 pmol L-1 for bisphenol Z. The recoveries of these bisphenols in milk, canned fruits, vegetables, and fish were higher than 99.00% with RSD (%) values lower than 1.50%.

Gold Nanoparticles/Nanographene-Based 3D Sensors Integrated in Mini-Platforms for Thiamine Detection.

Vitamins are essential for sustaining daily activities and perform crucial roles in metabolism, such as preventing vascular events and delaying the development of diabetic nephropathy. The ultrasensitive assessment of thiamine in foods is required for food quality evaluation. A mini-platform utilizing two 3D sensors based on nanographene and gold nanoparticles paste modified with protoporphyrin IX and protoporphyrin IX cobalt chloride is proposed for the detection of thiamine in blueberry syrup, multivitamin tablets, water, and a biological sample (urine). Differential pulse voltammetry was utilized for the characterization and validation of the suggested sensors. The sensor modified with protoporphyrin IX has a detection limit of 3.0 × 10-13 mol L-1 and a quantification limit of 1.0 × 10-12 mol L-1, whereas the sensor modified with protoporphyrin IX cobalt chloride has detection and quantification limits of 3.0 × 10-12 and 1.0 × 10-11 mol L-1, respectively. High recoveries (values greater than 95.00%) and low RSD (%) values (less than 5.00%) are recorded for both 3D sensors when used for the determination of thiamine in blueberry syrup, multivitamin tablets, water, and urine, demonstrating the 3D sensors' and suggested method's high reliability.

Gold nanoparticle-graphene quantum dots nanozyme for the wide range and sensitive electrochemical determination of quercetin in plasma droplets.

A gold nanoparticle/graphene quantum dots (AuNP/GQD) nanozyme-modified screen-printed carbon electrode (SPCE) was developed for fast and ultrasensitive determination of quercetin by square-wave voltammetry. The nanosensing device was inserted in miniaturized equipment. Under the optimal experimental conditions, a good linear relationship between oxidation peak current and concentration of quercetin within a very wide range of 1.0 × 10-10 to 1.0 × 10-3 mol L-1 was obtained, with a very low limit of detection of 3.3 × 10-11 mol L-1. To prove the performance of the method, the reproducibility was evaluated and the RSD values were lower than 5.3% and 5.1% for the intra-day and inter-day measurements, respectively. The method was applied to the sensitive determination of quercetin in human plasma droplets with recovery rates of 92.6 to 101.7%.Graphical abstract.

Application of phthalocyanines in flow- and sequential-injection analysis and microfluidics systems: A review.

Phthalocyanines and metallophthalocyanines play a very important role in the metabolism of living organisms through biological pigments or biochromes and are therefore also employed in numerous applications in analytical chemistry. In flow-, and sequential-injection analysis and microfluidic systems the role of phthalocyanines and metallophthalocyanines is centered as either that of analyte or that of a reagent or modifier in the determination of other species. This paper covers the attributes of phthalocyanines and metallophthalocyanines complexes as enhancements in chemical analysis in flow- and sequential injection analysis and microfluidic systems and points out the advantages and disadvantages in the implementation thereof.