The widespread application of enzymes in industrial chemical synthesis requires efficient process control to maintain high yields and purity. Flow injection analysis-electrospray ionization-mass spectrometry (FIA-ESI-MS) offers a promising solution for real-time monitoring of these enzymatic processes, particularly when handling challenging compounds like sugars and glycans, which are difficult to quickly analyze using liquid chromatography-mass spectrometry due to their physical properties or the requirement for a derivatization step beforehand. This study compares the performance of FIA-MS with traditional hydrophilic interaction liquid chromatography (HILIC)-ultra high-performance liquid chromatography (UHPLC)-mass spectrometry (MS) setups for the monitoring of the enzymatic synthesis of N-acetyllactosamine (LacNAc) using beta-1,4-galactosyltransferase. Our results show that FIA-MS, without prior chromatographic separation or derivatization, can quickly generate accurate mass spectrometric data within minutes, contrasting with the lengthy separations required by LC-MS methods. The rapid data acquisition of FIA-MS enables effective real-time monitoring and adjustment of the enzymatic reactions. Furthermore, by eliminating the derivatization step, this method offers the possibility of being directly coupled to a continuously operated reactor, thus providing a rapid on-line methodology for glycan synthesis as well.

A novel antipsychotic medication named brexpiprazole (BRX) is currently employed for the treatment of schizophrenia and other psychotic disorders. Because BRX\'s molecular structure includes a benzothiophene ring, it natively fluoresces. To detect BRX with precision and speed, a flow injection-fluorometric method, which is both sensitive and selective, is recommended. The fluorescence detection was conducted at 364 nm following excitation at 326 nm to capture the strong intrinsic fluorescence of BRX. The carrier solution employed was a mixture of phosphate buffer (pH 4, 10 mM) and acetonitrile (50: 50, v/v), with a flow rate of 0.5 mL min- 1. The calibration curve, based on peak areas, exhibited linearity within the concentration range of 20-350 ng mL- 1, with a remarkable correlation coefficient (r2) of 0.9999. The limit of quantitation was 9.7 ng mL- 1, and the limit of detection was found to be 3.2 ng mL- 1. This method was applied to quantify BRX in Neopression® tablets, achieving recovery within an acceptable range without interference from the tablet\'s additives. Additionally, the proposed approach was successfully utilised to quantify the drug in spiked human plasma. The approach underwent validation following ICH requirements.

A specific feature of mushrooms (including those of the genus Pleurotus) is their natural ability to absorb and accumulate many chemical substances present in their immediate environment, which makes them an excellent natural sorption material. Hence, fruiting bodies of mushrooms have been recognized for years as excellent indicators of the environment, reflecting its current state. Nevertheless, mushrooms can accumulate both health-promoting substances, such as bioelements, and toxic substances, such as heavy metals and organic compounds, including bisphenol A® (BPA). This organic chemical compound in the phenol group, although it has been withdrawn in the EU since 2010, is widely present in the environment around us. In the present experiment, we aimed to determine the effect of adding BPA to liquid media for in vitro cultures of Pleurotus spp. The biomass increases were determined. Moreover, the degrees of adsorption and desorption of BPA from the obtained freeze-dried biomass in two different environments (neutral and acidic) were determined as a function of time. This is the first study to determine the bioavailability of adsorbed BPA in obtained biomass by extracting the mycelium into artificial digestive juices in a model digestive system. BPA was added to the liquid Oddoux medium in the following amounts: 0.01, 0.5, and 0.5 g/250 mL of medium. The amounts of adsorbed and desorbed BPA were determined by flow injection analysis (FIA) with amperometric detection. The addition of BPA to the substrate reduced the biomass growth in each of the discussed cases. BPA adsorption by the mycelium occurred at over 90% and depended on the morphology of the mushroom (structure, surface development, and pore size). BPA desorption depended on the pH of the environment and the desorption time. Mushrooms are an excellent natural remedial material, but BPA is extracted into artificial digestive juices; therefore, consuming mushrooms from industrialized areas may have health consequences for our bodies.

This study presents a modified screen-printed carbon electrode (SPCE) to determine glucose in a custom-built flow injection system. The biosensor was constructed by immobilizing glucose oxidase on porous platinum nanoparticles decorated on multi-walled carbon nanotubes (GOx@PPtNPs@MWCTNs). The fabrication of the biosensor was completed by coating the GOx@PPtNPs@MWCTNs nanocomposite on an SPCE modified with a nanocomposite of poly(3,4-ethylenedioxythiophene) and Prussian blue (GOx@PPtNPs@MWCTNs/PEDOT@PB/SPCE). The fabricated electrode accurately measured hydrogen peroxide (H2O2), the byproduct of the GOx-catalyzed oxidation of glucose, and was then applied as a glucose biosensor. The glucose response was amperometrically determined from the PB-mediated reduction of H2O2 at an applied potential of -0.10 V in a flow injection system. Under optimal conditions, the developed biosensor produced a linear range from 2.50 μM to 1.250 mM, a limit of detection of 2.50 μM, operational stability over 500 sample injections, and good selectivity. The proposed biosensor determined glucose in human plasma samples, achieving recoveries and results that agreed with the hexokinase-spectrophotometric method (P > 0.05). Combining the proposed biosensor with the custom-built sample feed, a portable potentiostat and a smartphone, enabled on-site glucose monitoring.

Carmoisine dye, a red azo food colorant commonly utilized to impart a red color to synthetic food products, is the subject of this study. Here, we present a novel reversed flow injection analysis with a chemiluminescence detection (FIA-CL) method employing a newly developed homemade flow cell to determine carmoisine dye. This developed method is based on the inhibition effect of the dye on the chemiluminescence light (CL) emission generated from a luminal-hypochlorite system, whereby the reduction in CL intensity correlates directly with the concentration of carmoisine dye. Investigations into various analytical parameters were conducted to enhance method efficiency and applicability. A linear calibration graph of 4.0 to 100.0 µg mL-1 was established (R² = 0.9993), with a detection limit of LOD = 2.93 µg mL-1. Subsequent application of the proposed method to analyze gelatine dessert samples yielded results in reasonable agreement with those obtained using the reported HPLC method, as evidenced by student t-test and F-test analyses.

Converting solid iron oxide nanoparticles into a \"pseudo-water-soluble\" form before applying them to chemiluminescent reactions leads to enhance the chemiluminescence intensity. Using 8-hydroxyquinoline as a colloidal agent, a new, fast, and simple method of synthesizing pseudo-water-soluble Fe2O3 nanoparticles was developed. SEM, VSM, SAED, HRTEM, XRD, FTIR, and EDS techniques were used to characterize the synthesized Fe2O3 nanoparticles. Fe2O3 nanoparticles synthesized in this study have superior peroxidase-like activity (POD-like) and are stable under a wide range of pH and temperature. The chemiluminescence reaction of luminol-H2O2 is intensified and accelerated by a colloidal solution of Fe-nanoparticles/8-hydroxyquinoline. Reverse-flow injection analysis was employed to determine brilliant blue. A chemiluminescent sensing method based on iron oxide nanozymes was utilized for sensitive detection of the brilliant blue synthetic dye, achieving a limit of detection of 0.06 mg/L and a dynamic linear range of 0.1 to 50 mg/L. The recovery and relative standard deviations of real samples were found to be 97.83-99.93% and 0.09-3.07%, respectively. An analysis of a sample, from injection to obtaining the maximum peak, could be performed in less than one minute.

The spreading awareness of the health benefits associated with the consumption of plant-based foods is fueling the market of innovative vegetable products, including microgreens, recognized as a promising source of bioactive compounds. To evaluate the potential of oleaginous plant microgreens as a source of bioactive fatty acids, gas chromatography-mass spectrometry was exploited to characterize the total fatty acid content of five microgreens, namely, chia, flax, soy, sunflower, and rapeseed (canola). Chia and flax microgreens appeared as interesting sources of α-linolenic acid (ALA), with total concentrations of 2.6 and 2.9 g/100 g of dried weight (DW), respectively. Based on these amounts, approximately 15% of the ALA daily intake recommended by the European Food Safety Authority can be provided by 100 g of the corresponding fresh products. Flow injection analysis with high-resolution Fourier transform single and tandem mass spectrometry enabled a semi-quantitative profiling of triacylglycerols (TGs) and sterol esters (SEs) in the examined microgreen crops, confirming their role as additional sources of fatty acids like ALA and linoleic acid (LA), along with glycerophospholipids. The highest amounts of TGs and SEs were observed in rapeseed and sunflower microgreens (ca. 50 and 4-5 μmol/g of DW, respectively), followed by flax (ca. 20 and 3 μmol/g DW). TG 54:9, 54:8, and 54:7 prevailed in the case of flax and chia, whereas TG 54:3, 54:4, and 54:5 were the most abundant TGs in the case of rapeseed. β-Sitosteryl linoleate and linolenate were generally prevailing in the SE profiles, although campesteryl oleate, linoleate, and linolenate exhibited a comparable amount in the case of rapeseed microgreens.

An enzymatic amperometric uric acid (UA) biosensor was successfully developed by modifying a screen-printed carbon electrode (SPCE) with Prussian blue-poly(3,4-ethylene dioxythiophene) polystyrene sulfonate composite (PB-PEDOT:PSS). The modified SPCE was coated with gold nanoparticles-graphene oxide-chitosan composite cryogel (AuNPs-GO-CS cry). Uricase (UOx) was directly immobilized via chemisorption on AuNPs. The nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy. The electrochemical characterization of the modified electrode was performed by cyclic voltammetry and electrochemical impedance spectroscopy. UA was determined using amperometric detection based on the reduction current of PB which was correlated with the amount of H2O2 produced during the enzymatic reaction. Under optimal conditions, the fabricated UA biosensor in a flow injection analysis (FIA) system produced a linear range from 5.0 to 300 μmol L-1 with a detection limit of 1.88 μmol L-1. The proposed sensor was stable for up to 221 cycles of detection and analysis was rapid (2 min), with good reproducibility (RSDs < 2.90 %, n = 6), negligible interferences, and recoveries from 94.0 ± 3.9 to 101.1 ± 2.6 %. The results of UA detection in blood plasma were in agreement with the enzymatic colorimetric method (P > 0.05).

Bisphenol A (BPA) has been classified as an endocrine-disrupting substance that may cause adverse effects on human health and the environment. The development of simple and sensitive electrochemical biosensors is crucial for the rapid and effective quantitative determination of BPA. This work presents a study on electrochemical sensors utilizing gold nanoparticle-modified multi-walled carbon nanotubes (CNT/AuNPs). Glassy carbon electrodes (GCEs) and screen-printed electrodes (SPEs) were conveniently modified and used for BPA detection. AuNPs were electrodeposited onto the CNT-modified electrodes using the galvanostatic method. The electrodes were properly modified and characterized by using Raman spectroscopy, cyclic voltammetry (CV), and electrochemical impedance analysis (EIS). The electrochemical response of the sensors was studied using differential pulse voltammetry (DPV) and constant potential amperometry (CPA) for modified GCE and SPE electrodes, respectively, and the main analytical parameters were studied and optimized. Problems encountered with the use of GCEs, such as sensor degradation and high limit of detection (LOD), were overcome by using modified SPEs and a flow injection device for the measurements. Under this approach, an LOD as low as 5 nM (S/N = 3) was achieved and presented a linear range up to 20 μM. Finally, our investigation addressed interference, reproducibility, and reusability aspects, successfully identifying BPA in both spiked and authentic samples, including commercial and tap waters. These findings underscore the practical applicability of our method for accurate BPA detection in real-world scenarios. Notably, the integration of SPEs and a flow injection device facilitated simplified automation, offering an exceptionally efficient and reliable solution for precise BPA detection in water analysis laboratories.

This work introduces an innovative gold-leaf flow cell for electrochemical detection in flow injection (FI) analysis. The flow cell incorporates a hammered custom gold leaf electrochemical sensor. Hammered gold leaves consist of pure gold and are readily available in Thailand at affordable prices (approximately $0.085 for a sheet measuring 40 mm × 40 mm). Four sensing devices can be made from a single sheet of this gold leaf, resulting in a production cost of approximately $0.19 per sensor. Each electrochemical sensor has the gold leaf as the working electrode, together with a printed carbon strip, and a printed silver/silver chloride strip as the counter and reference electrodes, respectively. Initial investigations using cyclic voltammetry of a standard 1000 μmol L⁻1 iodide solution in 60 mmol L⁻1 phosphate buffer (PB) solution at pH 5, demonstrated performance comparable to that of a commercial screen-printed gold electrode. The hammered gold leaf electrode was then installed in a commercial flow cell as part of an FI system. A sample or standard iodide solution (100 μL) is injected into the first carrier stream of phosphate buffer (PB) solution, which then merges to mix with the second stream of the same buffer solution before flowing into the flow cell for amperometric detection of iodide. The optimized operating conditions include a fixed potential of +0.39 V (vs Ag/AgCl), and a total flow rate of 3 mL min⁻1. A linear calibration is obtained in the concentration range of 1 to 1000 μmol L⁻1 I- with a typical equation of μA = (0.00299 ± 0.00004) × (μmol L-1 I-) + (0.021 ± 0.020), and R2 = 0.9994. Analysis of iodide using this gold leaf-FI system is rapid with sample throughput of 86 samples h⁻1 and %RSD of a sample of 100 μmol L⁻1 I⁻ of 1.2 (n = 29). The limit of detection, (calculated as 2.78 × SD of regression line/slope), is 27 μmol L⁻1 I-. This method was successfully applied to determine iodide in nuclear emergency tablets.