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Aspartame is an artificial sweetener used in drinks and many foods. International Agency for Research on Cancer classified aspartame as possibly carcinogenic to humans (IARC Group 2B). In this study, a sensitive and selective spectrofluorimetric method was developed to detect aspartame. The method is based on switching on the fluorescence activity of aspartame upon its condensation with O‐phthalaldehyde (Roth's reaction) in the presence of 2‐mercaptoethanol. The reaction product was detected fluorometrically at λem of 438 nm after λex of 340 nm. All reaction conditions required to yield the optimal fluorescence intensity were observed and investigated. Furthermore, the approach was validated according to ICH guidelines. Upon plotting the concentrations of aspartame against their associated fluorescence intensity values, the relationship between the two variables was linear within the range of 0.5–3.0 μg/mL. Furthermore, the method was employed to analyze the quantity of aspartame in commercial packages and soft drinks with an acceptable level of recovery. In addition, the Green Solvents Selecting Tool, Complementary Green Analytical Procedure Index, and the Analytical Greenness Metric tool were used to evaluate the sustainability and the greenness of the developed methodology. [ABSTRACT FROM AUTHOR]

Dopamine is an important hormone and neurotransmitter, and its levels in human fluids can indicate stress, depression, and various mental disorders. Food products, as well as medications, affect its level in the human body greatly. Therefore, dopamine monitoring is crucial, and necessary for improving the quality of life. The priority is to search for simple and environmentally friendly sensor systems for the in vitro detection of dopamine, enabling mass utilization.In this study, we explored the use of o-phthalaldehyde (OPA) as an indicator for the detection of dopamine, with fluorescence in the visible range (λex/λem = 390/455 nm), while direct dopamine fluorescence measurement was in the UV range (λex/λem = 280/320 nm). The longer excitation/emission wavelengths of dopamine-OPA complex, as well as lower detection limits, are useful for developing a simple detection method using LEDs. Three types of poloxamers were tested as additives to improve the fluorescence signal from the reaction between dopamine and OPA. Pluronic F127 led to a 16-fold increase in the fluorescence. Utilizing 4% Pluronic F127 with OPA at pH 7 resulted in a linear response within concentration ranges of dopamine (0.5–3 µM), achieving a limit of detection of 0.015 µM. In contrast, a direct detection of dopamine within the same range exhibited a detection limit of 0.13 µM.

In this study, netilmicin (NTM) was selectively assessed in its dosage forms after a facile derivatization reaction. The proposed approach was based on the interaction between NTM and o‐phthalaldehyde/2‐mercaptoethanol (Roth's reagent). The reaction product was fluorometrically measured at λemission of 434 nm after λexcitation of 338 nm. All reaction conditions for achieving the optimum fluorescence switch‐on activity were visualized and monitored. Moreover, the method was validated under ICH guidelines, and was linear over the range 30–210 ng/ml after plotting netilmicin concentrations against the corresponding fluorescence intensity values. In addition, the selectivity of the developed method was investigated against either the co‐formulated drug (dexamethasone) or a common ophthalmic drop excipient (benzalkonium chloride) without interference from either of them. Furthermore, the developed method was applied to assay netilmicin in various samples of pharmaceutical eye drops with good recovery. Finally, multicriteria greenness and whiteness metrics were used to evaluate the sustainability, greenness, and whiteness of the approach. The applied tools were the AGREE algorithm, the RGB 12 algorithm, and HEXAGON. [ABSTRACT FROM AUTHOR]

This study reports a stepwise formation method of a chitosan membrane cross-linked with o-phthalaldehyde and its use as a polymer matrix in a quasi-solid-state-electrolyte- based supercapacitor. The proposed method of cross-linking in chitosan solution and evaporation of the solvent yielded a homogeneous and durable chitosan-o-phthalaldehyde membrane, which, after dipping in an aqueous 2 M lithium sulfate solution, formed a quasi-solid-state-electrolyte (CS/OPAQSSE). The prepared CS/OPA-QSSE was then used in an electric double layer capacitor (EDLC) cell to study its electrochemical properties. The electrochemical performance of the EDLC cell was determined by using the electrochemical impedance spectroscopy, cyclic voltammetry andgalvanostatic charging/discharging techniques. The results showed that the EDLC cell with the CS/OPA-QSSE is a fully functional and efficient device. The specific capacitance values calculated for the CS/OPA-QSSE EDLC (up to 115 F g~l) always surpassed the reference cell based on a commercial glass fibre separator Therefore, the proposed chitosan modification can be considered as a future alternative to produce other polysaccharide-based materials for electrochemical use. [ABSTRACT FROM AUTHOR]

In this manuscript, we describe the synthesis of low molar mass polycarbonate diols by acid cleavage of labile acetal linkages included in high molar mass poly(ether-co-carbonate-co-acetal) terpolymers. These copolymers were prepared by terpolymerization of propylene oxide (PO) with o-phthalaldehyde (OPA) and carbon dioxide (CO2), using triethyl borane (TEB) as activator and an onium salt as initiator. The advantage of this strategy of synthesis of poly(propylene carbonate) diols (PPC-diols) lies in the minute amounts of TEB and initiator required. Moreover, OPA could be isolated through post-hydrolysis of the terpolymers and recycled for subsequent use. We also demonstrated that this strategy works for the synthesis of low molar mass poly(ethylene carbonate) diols (PEC-diols). The structural integrity of the terpolymers before and after acid treatment, the characterization of low molar mass PPC-diols, and recycling process of OPA were carried out by 1H NMR spectroscopy, gel permeation chromatography, and matrix-assisted laser desorption ionization time of flight (MALDI-TOF) MS.

The Schiff bases and their complexes have an observed biological efficacy, so in the current study it has been prepared, characterized and evaluated the biological activity of some Schiff bases and their metal complexes with copper and nickel and based on ortho-phathaldehyde as a primary compound. A new Schiff bases ligands and metal complexes {[Cu(L)n(H2O)2]Cl2.mH2O and [Ni(L)n].mH2O, where L=N',N"'-((1E,1'E)-1,2-phenylenebis(methanylylidene)) di(benzohydrazide) L1, N',N"'-((1E,1'E)-1,2-phenylenebis (methanylylidene)) di(isonicotinohydrazide) L2, 1,2-bis((E)-(2-(2,4,6-trichlorophenyl)hydrazono)methyl) benzene L3; n = 1, 2; m = 0, 1, 3/2, 5/2} have been synthesized and elucidated by mass, FT-IR, 13C and 1HNMR, molar conductivity, flame-atomic absorption, magnetic susceptibility, Powder-XRD and TG analysis. The results showed that the L1 and L2 ligands behave as a tetra-dentate donor and were associated with metal ions in a molar ratio of 1:1, while L3 ligand was bidentate donor and associated with metal ions in 1:2 molar ratio. In addition, the geometric shapes of the prepared complexes were tetrahedral and square planar for Ni2+ and Zn2+ complexes, and octahedral for Cu2+ complexes. The effect of cellular toxicity in the laboratory has been examined by MTT assay for all compounds against the MCF-7 cancer breast cell line and found to have low efficacy except [Cu(L3)2(H2O)2] Cl2.H2O (5). The copper complex's molecular docking has been performed with breast cancer proteins using the MOE program, and found to target ERa, CDK6 and EGFR proteins by binding to hydrogen bonds and pi-interactions. [ABSTRACT FROM AUTHOR]

Dipeptidyl peptidase‐4 enzyme suppressant is a unique category of oral antidiabetic medication. Sitagliptin (STG) is a perfect member of this category and is pharmaceutically marketed alone or in combination with metformin. Here, the ideal application of an isoindole derivative for STG assay was developed using a feasible, easy‐to‐use, economic, and affordable method. STG as an amino group donor can form a luminescent derivative: isoindole on interaction with o‐phthalaldehyde and the existence of (2‐mercaptoethanol) 0.02% (v/v) as a thiol group donor. Excitation (339.7 nm) and emission (434.6 nm) wavelengths were used to monitor the isoindole fluorophore yield; moreover, each experimental variable was carefully investigated and adjusted. The calibration graph was constructed by plotting fluorescence intensities against STG concentrations, and controlled linearity was observed at concentrations ranging from 50 to 1000 ng/ml. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines were analyzed in depth to prove the technique validation. The implementation of the present technique was extended successfully to the evaluation of various types of STG dose forms and spiking samples of human plasma and urine. The developed technique was shown to be an effective, simple, and quick replacement for quality control and clinical study evaluation of STG. [ABSTRACT FROM AUTHOR]

Fluorescent probes have supplanted more conventional techniques in many experiments due to their versatility, sensitivity, and measurability. Topiramate, the objective compound lacks fluorogenic or chromophoric moieties rendering its direct analysis impractical. Without these groups, the molecule lacks the ability to fluoresce or absorb light in its natural state when subjected to a source of ultraviolet radiation. Tagging with a tracking reagent or fluorescent probing can overcome this phenomenon. Under the specific conditions In this study, a new, eco-friendly, practically applicable, and specific fluorometric approach to the assay of none fluorescent drug, topiramate was proposed. The planned analytical approach is dependent on the integration of fluorescence probes through the use of the o-phthalaldehyde reagent to yield a potent fluorescent product that can be measured fluorimetrically. Topiramate's unsubstituted amine moiety can condense with o-phthalaldehyde and thiol moiety in a buffered solution. After being excited at 339 nm. the product was measured at em 440 nm. This technique provides linearity within a concentration scale of 0.1–0.9 µg mL−1. The system quantum yield was evaluated by a comparative method. Also, the probe validation was analyzed in accordance with the standards set by the International Council for Harmonization (ICH). Excipients had no appreciable impact on the proposed probe's performance when testing topiramate in both batch powder and commercially available products. The results show remarkable consistency with the documented reference method with no obvious discrepancies between the two. Finally, the planned system was evaluated from the environmental side through different ecological metrics such as National Environmental Methods Index (NEMI), Eco-Scale Assessment (ESA), Green Analytical Procedure Index (GAPI), and Analytical GREEnness measure (AGREE) and showed a high degree of greenness (ES: 93/100; AGREE 0.75/1 and full green NEMI pictograms).

Treating large bone defects remains a considerable challenge for clinicians: bone repair requires scaffolds with mechanical properties and bioactivities. Herein, based on crosslinking o-phthalaldehyde (OPA) with amine groups, 4-arm polyethylene glycol (4armPEG)-OPA/Gelatin hydrogel loaded with bone morphogenetic protein 2 (BMP2) is prepared and a three dimensional (3D)-printed poly (lactic-co-glycolic acid) (PLGA) porous scaffold is filled with the hydrogel solution. The composite scaffold, with a compression modulus of 0.68 ± 0.097 GPa similar to the cancellous bone, has a porosity of 56.67 ± 4.72% and a pore size of about 380 µm, promoting bone growth. The hydrogel forms a porous network at low concentrations, aiding protein release and cell migration. The hydrogel degrades in approximately three weeks, and the scaffold takes five months, matching bone repair timelines. BMP2 release experiment shows a sustained BMP2 release with a 72.4 ± 0.53% release ratio. The ALP activity test and alizarin red staining shows effective osteogenic promotion, while RT-PCR confirms BMP2@Gel enhanced COL-1 and OPN expression. Animal experiments further validate the composite scaffold's bone repair efficacy. This study demonstrates the effectiveness of the hydrogel in releasing BMP2 and the mechanical support of the 3D-printed PLGA porous scaffold, providing a new treatment for bone defects., (© 2024 Wiley‐VCH GmbH.)

Aspartame is an artificial sweetener used in drinks and many foods. International Agency for Research on Cancer classified aspartame as possibly carcinogenic to humans (IARC Group 2B). In this study, a sensitive and selective spectrofluorimetric method was developed to detect aspartame. The method is based on switching on the fluorescence activity of aspartame upon its condensation with O-phthalaldehyde (Roth's reaction) in the presence of 2-mercaptoethanol. The reaction product was detected fluorometrically at λ em of 438 nm after λ ex of 340 nm. All reaction conditions required to yield the optimal fluorescence intensity were observed and investigated. Furthermore, the approach was validated according to ICH guidelines. Upon plotting the concentrations of aspartame against their associated fluorescence intensity values, the relationship between the two variables was linear within the range of 0.5-3.0 μg/mL. Furthermore, the method was employed to analyze the quantity of aspartame in commercial packages and soft drinks with an acceptable level of recovery. In addition, the Green Solvents Selecting Tool, Complementary Green Analytical Procedure Index, and the Analytical Greenness Metric tool were used to evaluate the sustainability and the greenness of the developed methodology., (© 2024 John Wiley & Sons Ltd.)

As the foremost category of carbon materials, carbon dots (CDs) have been extensively applied in many domains because of their special fluorescence features and outstanding biocompatibility. However, in early studies of fluorescent CDs, as the fluorescence wavelength of most CDs was restricted to the blue or green region and was excitation dependent, the application of CDs was limited. In this study, three representative CDs, fluorescing yellow, green, and blue, were synthesized under alkaline, neutral, and acidic circumstances, respectively, while using a hydrothermal method in which catechol and phthalaldehyde acted as carbon sources and methanol functioned as the reaction solvent. The carbon nuclei of the three fluorescent CDs all had comparable graphite structures. The diversity of photoluminescence (PL) emission from these three CDs was attributed mainly to the different sizes of the sp2 conjugated structures among them. Mixing synthesized CDs with epoxy resin, three colors (yellow, green, and blue) of LED using CIE coordinates (0.40, 0.44), (0.33, 0.46), and (0.21, 0.22), respectively, were successfully prepared.

The present work was to synthesis Schiff base ligand and its Mn(II) metal complex from the condensation of ophthalaldehyde and p-nitroaniline. The synthesized Schiff base ligand and metal complex were characterized by elemental analysis, FT-IR, 1H NMR, UV spectral studies. From the observed data, the complex is octahedral geometry for the Mn(II) complex. The biological activity involves antibacterial, antioxidant screening and DNA cleavage showed better activity. [ABSTRACT FROM AUTHOR]

This research aimed to develop a desolvation and 1,2-benzenedialdehyde crosslinking method to prepare crosslinked gelatin substances for emulsion stabilization. The oligo-gelatin conjugates and poly-gelatin nanoparticles could be formed at the 1,2-benzenedialdehyde concentration of 50 g/L and ≥ 150 g/L, respectively. The formation mechanism involved intra/inter-molecular amine-benzenedialdehyde-thiol and amine-benzenedialdehyde-amine crosslinking reactions. With increasing 1,2-benzenedialdehyde preparation concentrations (50–450 g/L), the crosslinked gelatin substance sizes increased from 81.5 ± 20.1 nm to 105.5 ± 20.8 nm in the dried state, and increased (from 35 ± 8 nm to 220 ± 36 nm) then decreased to 115 ± 28 nm in the water. Furthermore, the fish oil emulsions stabilized by the crosslinked gelatin substances showed different creaming stability: 250 g/L (43.5 ± 1.5 %) > 350 g/L (41.4 ± 1.0 %) > 450 g/L (37.5 ± 2.2 %) > 150 g/L (11.2 ± 0.4 %) > 50 g/L (0.0 ± 0.0 %). The results suggested this method was useful for preparing oligo-gelatin conjugates and poly-gelatin nanoparticles to stabilize traditional and Pickering emulsions, respectively. • 1,2-Benzenedialdehyde (BDA) was applied to prepare crosslinked gelatin substances. • Oligo-gelatin conjugates were formed at the 1,2-BDA concentration of 50 g/L. • Poly-gelatin nanoparticles were formed at the 1,2-BDA concentration of ≥150 g/L. • Expansion rates in water decreased with the increasing 1,2-BDA concentrations. • 1,2-BDA concentration of 50 g/L induced no emulsion creaming even at day 28. [ABSTRACT FROM AUTHOR]

Histidine (His) is an essential amino acid that plays an important biological role and associated with various pathological conditions. A simple and reliable method for the determination of endogenous histidine in human saliva was optimized and validated. The analyte was separated from the saliva matrix by cation exchange chromatography and detected fluorimetrically (λex/λem = 360/440 nm) after online, specific post-column derivatization (PCD) reaction with o-phthalaldehyde. The chemical and instrumental variables of the post-column reaction were optimized using Box–Behnken experimental design to achieve maximum sensitivity. Method validation was carried out employing the total-error concept. Histidine could be analyzed reliably in the range of 0.5–5.0 μΜ, with an LOD (S/N = 3) of 50 nM. Monte Carlo simulations and capability analysis were used to investigate the ruggedness of the PCD reaction. The sampling strategy, sample preparation and stability were also investigated. Seventeen saliva samples were successfully analyzed with histidine levels being in the range of 2.7–19.5 μΜ. [ABSTRACT FROM AUTHOR]

The measurement of phenylalanine in biological fluids for the diagnosis of phenylketonuria (PKU) in newborns and the monitoring/therapeutic drug monitoring of individuals with PKU are especially important. Owing to the importance of PKU monitoring in clinical medicine, a new fluorometric method was developed for the determination of L-phenylalanine in serum samples. This method is based on the relationship between phenylalanine ammonia-lyase (PAL) and o-phthalaldehyde (OPA). PAL catalyzes the conversion of phenylalanine to ammonia and trans-cinnamic acid. The formed ammonia reacts with OPA in the presence of sodium sulfite, giving a fluorescent product. The presence of sulfide in an alkaline environment prevents OPA from reacting with other amino acids while allowing it to react only with ammonia. Method characterization and optimization studies, such as the effects of pH, temperature, and interferents, were carried out. The amount of L-phenylalanine in a human serum sample was successfully determined by using the fluorescence emission intensity of the fluorescent product formed as a result of the reaction between OPA and ammonia. The linear range of the method is between 10 μM and 10 mM. The obtained result showed good agreement with the results of the biochemistry analysis laboratory. Recoveries of 95.41% and 73.39% were obtained for phenylalanine and ammonia, respectively. This PAL–OPA–based fluorometric method for phenylalanine is practical, easy to operate, low cost, highly sensitive, and selective and can also be used for the simultaneous determination of ammonia in human serum samples. [ABSTRACT FROM AUTHOR]

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In the present study, we report an automated fluorescence sensor for the determination of hydrazine in various water samples based on the concept of zone fluidics. Hydrazine and O-phthalaldehyde react through a unique mechanism in acidic medium (pH = 1.5) and without the presence of additional nucleophilic compounds. Another interesting feature of the proposed reaction is that it is not based on the Red/Ox properties of hydrazine, enhancing further the selectivity of the analytical procedure. The produced hydrazone exhibits high fluorescence at Ex = 318/Em = 376 nm. Using 120 s as a stopped flow step and temperature of 70 °C, we achieved satisfactory sensitivity for the determination of the analyte at a microgram per liter level with a limit of detection of 1.4 μg L−1 and an analysis rate of 12 h−1. The absence of matrix effect enabled the direct analysis of drinking (tap, mineral, table) and boiler feedwater samples with percent recoveries in the range of 91–111%. [ABSTRACT FROM AUTHOR]

A simple and cost effective method was developed for enantiomeric separation of levetiracetam (LEV) and chiral impurity R-enantiomer in raw material and tablets. The method based on derivatization of racemate using o-phthalaldehyde and N-acetyl-L-cysteine in basic borate buffer. The diastereomeric isoindole derivatives were separated by HPLC efficiently using C18 column and ammonium acetate (20 mM, pH: 7.3): methanol (55:45) as mobile phase, and isocratic elution at a flow rate of 1.0 mL/min. The optimal fluorescence detection parameters were λex = 330 nm, and λem = 450 nm. The method was validated and applied to raw material and tablet samples. Enatiomeric resolution was achieved within 9 minutes, and the resolution factor was more than 2. Calibration curves were linear over the range 1-50 and 0.06-8.0 (µg/mL) for LEV and R-enantiomer, respectively. LOD and LOQ of R-enantiomer were 0.02, and 0.06 (µg/mL), respectively. The method was sensitive, accurate, and precise. The developed method had been applied successfully to determine R-enantiomer in LEV raw material and tablets and can be used in quality control laboratories. [ABSTRACT FROM AUTHOR]

A facile and sensible spectrofluorimetric approach for the measurement of two antipsychotic medications, aripiperazole (ARP) and clozapine (CLZ), was devised and validated. The approach involves reacting the examined medicines with o-phthalaldehyde in the presence of β-mercaptoethanol in a borate buffer of pH 9.0 and pH 10 for ARP and CLZ, respectively, to produce a robustly fluorescent compound that is detected at 450 nm following excitation at 340 nm. The experimental variables influencing the performance and product stability were thoroughly investigated and optimized. Under optimal conditions, the intensity of the fluorescence was linear during a concentration range of 0.1–0.5 μg/mL, with a limit of detection (0.0391 and 0.0400 μg/mL) and limit of quantitation (0.1035 and 0.1332 μg/mL), respectively, for ARP and CLZ. The suggested approach was successful in analyzing commercialized tablets. A statistical investigation of the results produced by the suggested and standard methods showed no remarkable variation in the precision and accuracy of the two approaches. A chemical mechanism using o-phthalaldehyde was proposed.

Biomass carbon dots (CDs) have the characteristics of being green, nontoxic, inexpensive, and simple to prepare, and they can be used in luminescence-related fields. In this study, red, green, and blue luminescent CDs were synthesised by a simple hydrothermal method under alkaline, neutral, and acidic conditions using TA as carbon source and o-phthalaldehyde as blend. The unique optical properties of these CDs are due to the differences in their degrees of conjugation, which can be controlled by the pH value of the reaction system. These three kinds of biomass CDs have good applications in light-emitting diodes (LEDs). By mixing biomass CDs with epoxy resin, warm, and cold white LEDs with Commission Internationale de l’Elcairage (CIE) coordinates (0.35, 0.36) were successfully constructed on extremely stable multicolour CDs. This study shows that these biomass CDs are a promising material for white LED lighting.

Emerging evidence suggests that amino acid (AA) neurotransmitters play important roles in the pathophysiological processes of cerebral ischemia. In this work, an HPLC with fluorescence detection (HPLC‐FLR) method was developed for the simultaneous determination of 18 AAs in the cortex and plasma after cerebral ischemia in mice. The ischemia model was prepared by bilateral common carotid artery occlusion, and then the cortex and plasma of the sham, ischemia, and naringenin groups were collected. Based on the protein precipitation method, a simple and effective sample preparation method was developed. The treated sample contained minimal proteins and lipids. The analysis of the sample was performed by the proposed HPLC‐FLR method in combination with o‐phthalaldehyde. The results showed a statistically significant increase in excitatory AAs (aspartic acid and glutamic acid), inhibitory AAs (glycine and 4‐aminobutyric acid), phenylalanine, citrulline, isoleucine, and leucine levels, and a decrease of glutathione and phenylalanine levels when compared with the sham group in the cortex. Besides, the administration of naringenin had significant effects on excitatory AAs, inhibitory AA (glycine), glutamine, tyrosine, phenylalanine, and leucine levels when compared with the sham group in the cortex. These findings could be utilized in studying and clarifying the mechanisms of ischemia. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two spectrofluorimetric methods were developed for determination of natamycin. • Hantzsch condensation reaction is the principle of the first method. • Second approach relied on fluorogenic derivatization with o -phthalaldehyde. • The variables were studied and optimized using full factorial design. • Natamycin determination in bread, water and eye drops was accomplished. Natamycin (NATA) is a widely used food preservative. It is a non-fluorescent compound; hence, a derivatization reaction to produce a fluorescent derivative was necessary for its analysis. In this context, two derivatization reactions were applied to develop two spectrofluorimetric methods for determining NATA. Method I relies on Hantzsch condensation reaction between the primary amine group of NATA and acetylacetone-formaldehyde (AAF) reagent to produce a highly fluorescent dihydropyridine derivative that is measured at λ em /λ ex of 481/415 nm, while Method II based on the reaction of the primary amine group of NATA with o -phthalaldehyde in the presence of N-acetylcysteine which resulted in isoindole fluorophore derivative that can be monitored at λ em /λ ex of 433/338 nm. The experimental variables of both methods were optimized using full-factorial designs. Under the optimum conditions, the proposed methods enabled the determination of NATA over concentration ranges of 50.0–500.0 ng mL−1 (LOD = 13 ng mL−1) for Method I and 0.50–10.0 μg mL−1 (LOD = 0.16 μg mL−1) for Method II. Both methods were efficiently applied to assay NATA in ophthalmic eye drops. The application was extended to include bread and environmental water samples based on the nano-scale sensitivity of Method I. [ABSTRACT FROM AUTHOR]

In this manuscript, we describe the synthesis of low molar mass polycarbonate diols by acid cleavage of labile acetal linkages included in high molar mass poly(ether- co -carbonate- co -acetal) terpolymers. These copolymers were prepared by terpolymerization of propylene oxide (PO) with o-phthalaldehyde (OPA) and carbon dioxide (CO 2), using triethyl borane (TEB) as activator and an onium salt as initiator. The advantage of this strategy of synthesis of poly(propylene carbonate) diols (PPC-diols) lies in the minute amounts of TEB and initiator required. Moreover, OPA could be isolated through post-hydrolysis of the terpolymers and recycled for subsequent use. We also demonstrated that this strategy works for the synthesis of low molar mass poly(ethylene carbonate) diols (PEC-diols). The structural integrity of the terpolymers before and after acid treatment, the characterization of low molar mass PPC-diols, and recycling process of OPA were carried out by 1H NMR spectroscopy, gel permeation chromatography, and matrix-assisted laser desorption ionization time of flight (MALDI-TOF) MS. [ABSTRACT FROM AUTHOR]

Immobilized enzymes have been widely used for their efficiency, economy, and environment friendly. In this case, a simpler and effective immobilization method has been developed. In this study, the enzyme immobilized by magnetic beads with genipin (MGE) was prepared by mixing genipin-modified nano-Fe 3 O 4 with (R)− 1-phenylethanol dehydrogenase ((R)-PEDH) and recombinant glucose dehydrogenase (rGDH), and the magnetic cross-linked enzyme aggregates (MCLEAs) was prepared by stirring a mixture of the sulfur precipitate of the (R)-PEDH and rGDH, poly-L-lysine, and cross-linkers. When o-phthalaldehyde (o-PA) was used as a cross-linking agent for the MCLEAs preparation, a protein loading of 99.9% and 62.93% recovery activity of (R)-PEDH and 70.12% of rGDH were obtained. Compared to the MGE, the MCLEAs possessed better enzyme activity recovery. Furthermore, this study tried the synthesis of (R)− 1-(furan-2-yl) ethanol by the immobilized enzymes and obtained a concentration of 1.10 mM for the MCLEAs and 0.24 mM for the MGE at 48 h. This study explored a facile method for co-immobilization of (R)-PEDH and rGDH to synthesize (R)− 1-(furan-2-yl) ethanol. [Display omitted] • A comparison of the enzyme activity of MCLEAs and MGE. • The process of the preparation of MCLEAs using o-phthalaldehyde as the cross-linker was explored. • The MCLEAs was applied for the synthesis of (R)− 1-(furan-2-yl) ethanol. [ABSTRACT FROM AUTHOR]

Herein, we report a new automated flow method based on zone fluidics for the simultaneous determination of homocysteine and homocysteine thiolactone using fluorimetric detection (λext = 370 nm/λem = 480 nm). Homocysteine thiolactone is hydrolyzed on-line in alkaline medium (1 mol L−1 NaOH) to yield homocysteine, followed by reaction with o-phthalaldehyde in a single step. Derivatization is rapid without the need of elevated temperatures and stopped-flow steps, while specificity is achieved through a unique reaction mechanism in the absence of nucleophilic compounds. Mixtures of the analytes can be analyzed quantitatively after specific separation with fluorosurfactant-capped gold nanoparticles that are selectively aggregated by homocysteine, leaving the thiolactone analogue in solution. As low as 100 nmol L−1 of the analyte(s) can be quantified in aqueous solutions, while concentrations > 2 μmol L−1 can be analyzed in artificial and real urine matrix following 20-fold dilution. The percent recoveries ranged between 87 and 119%.

Polysaccharide-based vaccines cannot stimulate long-lasting immune response in infants due to their inability to elicit a T-cell-dependent immune response. This has been addressed using conjugation technology, where conjugates were produced by coupling a carrier protein to polysaccharides using different conjugation chemistries, such as cyanylation, reductive amination, ethylene diamine reaction, and others. Many glycoconjugate vaccines that are manufactured using different conjugation technologies are already in the market for neonates, infants and young children (e.g., Haemophilus influenzae type-b, Streptococcus pneumoniae and Neisseria meningitidis vaccines), and all of them elicit a T-cell dependent immune response. To manufacture glycoconjugate vaccines, the capsular polysaccharide is first activated by converting its hydroxyl groups to aldehyde-, cyanyl-, or cyanate ester groups, depending on the conjugation chemistry selected. The oxidized and reduced aldehyde functional groups of the polysaccharides are subsequently reacted with the amino groups of carrier protein by reductive amination to form a stable amide bond. In CDAP-based conjugation, the polysaccharide -OH groups are activated to form cyanyl-, or cyanate ester groups to react with the amino groups of carrier protein and forms an isourea bond. Understanding the extent of polysaccharide activation/modification is essential since it directly influences the molar mass of the conjugate, its stability, and the immunogenicity of the product. Reported methods are available to estimate the aldehyde groups of polysaccharides generated by reductive amination. However, no method is available to quantify the cyanyl or cyanate ester (-OCN) groups generated by cyanylation with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP). We report a novel strategy using an O-phthalaldehyde (OPA) derivatization process followed by size-exclusion chromatography (SEC) high-performance liquid chromatography (HPLC) separation and UV detection. The cyanate ester groups on the activated polysaccharide directly reveal the extent of polysaccharide activation/modification and the residual activated groups in the purified conjugates. This method would be useful for conjugate vaccine manufacturing using CDAP chemistry., Competing Interests: Declaration of Competing Interest Authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Rapid methods for amino acid determination are desired to reduce running times, and the main factors involved in the rapid separation of these compounds in HPLC are the columns, solvents, and gradient. The present study refers to a method optimization to rapidly analyze 19 amino acids in RP-HPLC/DAD with pre-column derivatization using o-phthalaldehyde. To evaluate the method's robustness, Indian Pale Ale-IPA beers and wines from the San Francisco Valley-SFV and Chapada Diamantina-CHD, Brazil, were analyzed. The method showed acceptable linearity (R 2  > 0.992), precision (CV < 3.96%), recovery (74.2-113%), detection limits (<0.56 mg/L), and quantification limits (<3.62 mg/L) and separation gradient in 18.5 min. IPA beers were discriminated from wines by arginine, asparagine, tryptophan, alanine, phenylalanine, and tyrosine contents. Furthermore, CHD wines were discriminated from SFV wines by asparagine, glutamine, arginine, cystine, tyrosine, and leucine. In conclusion, a rapid method for amino acid determination was optimized and validated for wines and beers., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In the present study we report the reaction between homocysteine and o‐phthalaldehyde under flow conditions. Homocysteine reacts on‐line with the derivatization reagent in a strong alkaline medium and in the absence of nucleophilic reagents to yield a fluorescent derivative (λex/λem = 370/480 nm). The reaction variables were investigated using the concept of zone fluidics. Selectivity factors against other compounds were calculated at 10‐fold excess. The findings formed the basis of an automated proposed method that was found to be linear in the range 0.1–1.5 μmol L−1, with a limit of detection of 20 nmol L−1 and relative standard deviation < 0.5% (within‐day) and 3.2% (between‐day). The method proved to be rapid, offering a practical sampling rate of 24 h−1 and accurate following application to an artificial urine matrix with minimum dilution. [ABSTRACT FROM AUTHOR]

Abstract o-Phthalaldehyde (OPA) reacts with O-protected tris(hydroxyalkyl)aminomethanes in the presence of 1-propanethiol to afford a novel class of stable isoindoles. Steric protection provided by the bulkiness of C 3-symmetric primary amines derived from tris(hydroxymethyl)aminomethane could be significant for the stabilization of 1-alkylthio-2-alkyl-substituted isoindoles derived from OPA. A plausible reaction mechanism is proposed to explain the formation of the isoindole and an isoindolin-1-one by-product.

Fermented vegetables and fruits are a good source of selected vitamins, antioxidants, microelements and revealed immune-boosting properties. The appropriate content of health-promoting compounds and probiotics allows you to qualify juices from fermented vegetables or fruits as better-for-you food. Notwithstanding, biogenic amines in this type of food are also detected due to the fermentation process, which may negatively affect their health-promoting properties. In this study, various biogenic amines were determined in juices obtained during the pressing of fermented vegetables (white and red cabbage, cucumbers, tomatoes, cauliflowers, celery, celery leaves, broccoli, and beetroots). The level of monamines (histamine, tyramine, tryptamine, and phenylethylamine), diamines (putrescine, cadaverine), and polyamines (spermidine and spermine) was discussed. The significant discrepancies between all the tested determined compounds as well as the sums of the BAs in tested samples, were observed. The calculated values of BAs sum varied from 6.36 mg L−1 (fermented tomato juice) to 116.52 mg L−1 (fermented cucumber juice). Among the determined amines, the majority were histamine, tyramine, putrescine, and cadaverine (from 66% to 97–98% of total biogenic amines level). Moreover, depending on the type of tested juice, the amount of histamine and tyramine in the full content of BAs was between 0.44% (for fermented red cabbage juice) and 68% (for fermented broccoli juice). According to our knowledge, this is the first time that the determination of biogenic amines in fermented vegetable juices has been studied. • Biogenic amines were determined in fermented vegetable juices. • The minimal sample preparation and derivatization of BAs with OPA were applied. • The chromatographic determination procedure was used. • Obtained results provide new knowledge about BAs amount in healthy food. • Observed level of BAs indicates fermented juices as not undesirable for consumers. [ABSTRACT FROM AUTHOR]

Objectives: The American Conference of Governmental Industrial Hygienists recommends a threshold limit value-ceiling (TLV-C) of 0.1 ppb for occupational exposure to ortho-phthalaldehyde (OPA) used in washing endoscope probes. To adhere to this extremely low exposure limit, this case study aimed to reduce OPA exposure concentrations of workers during immersion washing of an endoscope probe body. This was achieved by attaching a new duct and hood to the existing ceiling exhaust system., Methods: The type of hood was determined by calculating and comparing the capture velocity obtained by assuming either an exterior or an enclosing hood. Additionally, the effect on improving the working environment was tested before and after the installation of the hood by measuring the OPA vapor concentration., Results: The calculated capture velocities of the exterior and enclosing hoods were 0.05 m/s and 0.19 m/s, respectively. Considering the operability, the exterior hood was more appropriate; however, the calculated capture velocity indicated potential inadequacy in meeting the TLV-C requirement, leading to the adoption of the enclosing hood. The OPA vapor concentration in ceiling value measurements taken after the enclosing hood was fitted was reduced to 0.2 ppb, that is, 1/10 of the original concentration., Conclusions: Although the environmental concentration after the improvement still exceeded the TLV-C of 0.1 ppb, this study's findings indicate that even substances with extremely low occupational exposure limits can be managed with appropriate local exhaust ventilation., (© The Author(s) [2024]. Published by Oxford University Press on behalf of Journal of Occupational Health.)

Gizzerosine [2-amino-9-(4-imidazolyl)-7-azanonanoic acid] is a toxic amino acid formed from histamine and lysine at high temperatures, and may be present in foodstuffs (e.g., fishmeal and meat-bone meal) for animals including cats and dogs. Here we developed a simple, rapid, sensitive, specific, and automated method for the analysis of gizzerosine in foodstuffs by high-performance liquid chromatography (HPLC) involving pre-column derivatization with o-phthaldialdehyde (OPA) in the presence of N-acetylcysteine (instead of the usual 2-mercaptoethanol or ethanethiol reagent). OPA reacted immediately (within 1 min) with gizzerosine in an autosampler at room temperatures (e.g., 20-25 °C), and their derivative was directly injected into the HPLC column. The highly fluorescent gizzerosine-OPA derivative was well separated from the OPA derivatives of all natural amino acids known to be present in physiological fluids (e.g., plasma), proteins and foodstuffs, and was detected at an excitation wavelength of 340 nm and an emission wavelength of 450 nm. The total time for chromatographic separation (including column regeneration) was 20 min per sample rather than 40 min and longer in previous HPLC methods. The detection limit for gizzerosine was at least 6 pmol/ml in an assay solution (HPLC vial) or at least 0.09 pmol per injection into the HPLC column. The analysis of gizzerosine was linear between 1 and 100 pmol per injection. When gizzerosine was extracted from foodstuffs, its detection limit was at least 875 pmol/g foodstuff or at least 0.21 mg/kg foodstuff. Our routine HPLC technique does not require any cleanup of samples or the OPA derivatization products (including the OPA-gizzerosine adduct), and is applicable for the analysis of gizzerosine in both foodstuffs and animal tissues., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

In this study, netilmicin (NTM) was selectively assessed in its dosage forms after a facile derivatization reaction. The proposed approach was based on the interaction between NTM and o-phthalaldehyde/2-mercaptoethanol (Roth's reagent). The reaction product was fluorometrically measured at λ emission of 434 nm after λ excitation of 338 nm. All reaction conditions for achieving the optimum fluorescence switch-on activity were visualized and monitored. Moreover, the method was validated under ICH guidelines, and was linear over the range 30-210 ng/ml after plotting netilmicin concentrations against the corresponding fluorescence intensity values. In addition, the selectivity of the developed method was investigated against either the co-formulated drug (dexamethasone) or a common ophthalmic drop excipient (benzalkonium chloride) without interference from either of them. Furthermore, the developed method was applied to assay netilmicin in various samples of pharmaceutical eye drops with good recovery. Finally, multicriteria greenness and whiteness metrics were used to evaluate the sustainability, greenness, and whiteness of the approach. The applied tools were the AGREE algorithm, the RGB 12 algorithm, and HEXAGON., (© 2023 John Wiley & Sons Ltd.)

Objective: To compare the effectiveness of disinfection protocols utilizing a ultraviolet (UV) Smart D60 light system with Impelux™ technology with a standard Cidex ortho-phthalaldehyde (OPA) disinfection protocol for cleaning flexible fiberoptic laryngoscopes (FFLs)., Methods: Two hundred FFLs were tested for bacterial contamination after routine use, and another 200 FFLs were tested after disinfection with one of four methods: enzymatic detergent plus Cidex OPA (standard), enzymatic detergent plus UV Smart D60, microfiber cloth plus UV Smart D60, and nonsterile wipe plus UV Smart D60. Pre- and post-disinfection microbial burden levels and positive culture rates were compared using Kruskal-Wallis ANOVA and Fisher's two-sided exact, respectively., Results: After routine use, approximately 56% (112/200) of FFLs were contaminated, with an average contamination level of 9,973.7 ± 70,136.3 CFU/mL. The standard reprocessing method showed no positive cultures. The enzymatic plus UV, microfiber plus UV, and nonsterile wipe plus UV methods yielded contamination rates of 4% (2/50), 6% (3/50), and 12% (6/50), respectively, with no significant differences among the treatment groups (p > 0.05). The pre-disinfection microbial burden levels decreased significantly after each disinfection technique (p < 0.001). The average microbial burden recovered after enzymatic plus UV, microfiber plus UV, and nonsterile wipe plus UV were 0.40 CFU/mL ± 2, 0.60 CFU/mL ± 2.4, and 12.2 CFU/mL ± 69.5, respectively, with no significant difference among the treatment groups (p > 0.05). Micrococcus species (53.8%) were most frequently isolated, and no high-concern organisms were recovered., Conclusion: Disinfection protocols utilizing UV Smart D60 were as effective as the standard chemical disinfection protocol using Cidex OPA., Level of Evidence: NA Laryngoscope, 133:3512-3519, 2023., (© 2023 The Authors. The Laryngoscope published by Wiley Periodicals LLC on behalf of The American Laryngological, Rhinological and Otological Society, Inc.)

A new, simple, and rapid photochemical reaction of o‐phthalaldehyde with C60 has been disclosed. This reaction afforded exclusively the unanticipated C60‐phthalide derivative 11 in good yield. The formation of this product is consistent with the intervention of a key free‐radical intermediate –a benzylic radical– in the course of the reaction. The structure of 11 has been determined by the combined use of experimental and theoretical NMR studies. In the course of this study we further disclosed a new mode of radical reactivity of C60 with a series of substituted phthalides (2, 15–17) catalyzed by tetrabutylammonium decatungstate. [ABSTRACT FROM AUTHOR]

A new, simple, and rapid photochemical reaction of o‐phthalaldehyde with C60 has been disclosed. This reaction afforded exclusively the unanticipated C60‐phthalide derivative 11 in good yield. The formation of this product is consistent with the intervention of a key free‐radical intermediate –a benzylic radical– in the course of the reaction. The structure of 11 has been determined by the combined use of experimental and theoretical NMR studies. In the course of this study we further disclosed a new mode of radical reactivity of C60 with a series of substituted phthalides (2, 15–17) catalyzed by tetrabutylammonium decatungstate. [ABSTRACT FROM AUTHOR]

A completely new voltammetric method has been developed for quantitative determination of food additive Taurine (Tau) in energy drinks. This electroanalytical method is based on voltammetric oxidation of o -phthalaldehyde-ethanthiol derivative of Tau at glassy carbon electrode in 95% methanol containing 0.1 mol L−1 lithium perchlorate. Working conditions necessary for quantitative Tau derivatization reaction and electrochemical detection using square wave voltammetry were optimized. Linear range from 1.0 × 10−5 to 1.0 × 10−4 mol L−1 characterized by coefficient of determination 0.9998, limits of quantification 6.8 × 10−6 mol L−1 and detection 2.1 × 10−6 mol L−1 were obtained at pulse amplitude 50 mV and frequency 80 Hz. Analytical method of calibration curve was used for evaluation of Tau content in several commercially available energy drinks. The procedure was validated using standard reference high performance liquid chromatography (HPLC) method. Both methods showed nearly identical Tau content, around 0.35% (w/w). Besides its reliability to the Tau determination, that is totally comparable to reference method used, present voltammetric approach is more advantageous on the economic and simplicity basis. Finally, developed voltammetric method could find employment in food quality control. Image 1 • The first scientific work focusing on reliable voltammetric determination of taurine. • Electroanalytical method based on anodic oxidation of isoindole derivative. • Fully comparable with the standard reference chromatographic method. • Suitable method for analysis of foodstuffs containing dominantly one amino acid. [ABSTRACT FROM AUTHOR]

We have developed an indirect fluorescence method for the determination of nitrite based on two reactions. The S-nitrosocaptopril produced by the first reaction between nitrite and excess captopril is not fluorescent. The fluorescent product produced by the residual captopril with glycine and o-phthalaldehyde is then measured and related to the nitrite concentration. We have optimized comprehensively the reaction condition parameters, including the thiol regent for the two reactions, reaction temperature and pH value for the first reaction, and the choice of amino acid, pH value, the ratio of reactants, buffer concentration, reaction temperature, and time for the second fluorescence reaction. Potential interferences by 8 cations and 10 anions on the fluorescence intensity were slight except for iodate and periodate which could likely be removed by addition of a reducing agent. For the analytical figures of merit, the limits of detection and quantitation of nitrite are 0.8 and 2.5 nM, respectively. The fluorescence intensity is found to linearly decrease with increasing nitrite from 0 to 140 nM. The method has shown to have good interday (<8%) and intraday precision (1-4%). The formation of nitrite from nitrate due to microbial degradation of spinach can be easily followed. Although the method requires a two-step reaction sequence that takes a significant analysis time, the safety and cost of the reagents (no carcinogenic amino naphthalene compounds) as well as excellent analytical figures of merit are significant advantages. [ABSTRACT FROM AUTHOR]

A thermochemically-induced fluorescence derivatization (TIFD) method for the determination of metolachlor (MET) based on the o-phthalaldehyde thermo product complex of MET (OPA-MET) enhanced with either hydroxypropyl-γ-CD (HP-γ-CD) or dimethyl-β-CD (DM-β-CD) was investigated. The analytical conditions of the TIFD method were the same for the complexes, except for the solvent. The fluorescence enhancement was highlighted for the OPA-MET complex in the presence of cyclodextrins (CDs). Besides the stability of the OPA-MET:CD inclusion complexes, which corroborates the reproductibility of the TIFD method, a 1:1 stoichiometric ratio between OPA-MET was obtained in both of the organized environments (CDs). The binding constants (K1) of the inclusion complexes OPA-MET: HP-γ-CD and OPA-MET: DM-β-CD of 1:1 type are (264 ± 36) L·mol−1 and (173 ± 17) L·mol−1, respectively. Under the optimal conditions, the linear dynamic range of the TIFD method is 10–580 ng·mL−1 and correlation coefficients obtained through calibration curves were close to unity. Limits of detection (LODs) and quantification (LOQs) are in the ranges 0.06–0.09 ng·mL−1 and 0.2–0.3 ng·mL−1, respectively. A solid phase extraction (SPE) procedure successfully combined with the TIFD method in the presence of cyclodextrins, for quantitative analysis of samples spiked with metolachlor, led to satisfactorly accurate values (recovery: 92.2–121% and RSD: 1.1–1.3%). [ABSTRACT FROM AUTHOR]

• Application of NDA as a post column reagent. • The Pulsed-Post Column concept minimized NDA consumption. • Parallel development of OPA and OPA-NAC based methods. • Determination of histamine in food samples. • Comparison of the results and methods. In the present study, naphthalene-2,3-dicarboxaldehyde (NDA) was used in on-line post column derivatization (PCD) coupled to liquid chromatography under the new concept of Pulsed-PCD. In Pulsed-PCD, the reagents are introduced into the flowing stream of the mobile phase under precise timing overlapping the eluted analyte. The consumption of the reagents is minimized to a few microliters, resulting in a significant advantage, that is the use of expensive reagents in PCD. For this reason, NDA-CN chemistry was used for the determination of histamine in food samples, such as eggplant and spinach. Two additional methods were developed based on the reaction of histamine with o-phthalaldehyde (OPA), namely the classic OPA – nucleophilic compound reaction and the specific OPA – histamine reaction in alkaline medium. The chromatographic conditions and the Pulsed-PCD conditions were investigated, while the analytical figures of merit were satisfactory. In all three methods, a pulse of 50 μL was used (OPA/NDA + Buffer), reducing dramatically the consumption of PCD reagents. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first HPLC-PCD method for the determination of GSH and its disulfide in flour samples. • Both analytes are determined in a single run, avoiding extra reduction/subtraction steps. • Chromatographic separation and extraction are accomplished in the absence of organic solvents. • Quantification is possible at the nmol g−1 levels for GSH/GSSG. • There is absence of matrix effects and interferences from the flour samples. In the present report we propose an HPLC method coupled to on-line post column derivatization for the simultaneous determination of glutathione and its disulfide in flour samples. The extraction of the analytes from the sample matrix was investigated in terms of efficiency, stability and compatibility with the analytical method. The selection of o-phthalaldehyde at high alkaline medium as post column reaction system enabled the determination of both analytes in a single run at reasonable separation times (<10 min). Fluorimetric detection allowed determination at the low nmol g−1 (5–75 nmol g−1) levels in the absence of matrix interferences from endogenous compounds. The LOD values were 1.2–1.3 nmol g−1 and the precision better than 7.2% in all cases. Various commercially available flour samples (wheat, corn, rice) were analyzed and were found to contain glutathione and its disulfide in the ranges of 29–243 and 8–84 nmol g−1 respectively. Only in one rice flour sample the levels of GSH were < LOQ of the method. [ABSTRACT FROM AUTHOR]

In the present study, the determination of histidine (HIS) by an on-line flow method based on the concept of zone fluidics is reported. HIS reacts fast with o-phthalaldehyde at a mildly basic medium (pH 7.5) and in the absence of additional nucleophilic compounds to yield a highly fluorescent derivative (λex/λem = 360/440 nm). The flow procedure was optimized and validated, paying special attention to its selectivity and sensitivity. The LOD was 31 nmol·L−1, while the within-day and day-to-day precisions were better than 1.0% and 5.0%, respectively (n = 6). Random urine samples from adult volunteers (n = 7) were successfully analyzed without matrix effect (−1 with percentage recoveries in the range of 87.6%–95.4%.

Introduction: Alendronate sodium enhances bone formation and increases osteoblast proliferation and maturation and leads to the inhibition of osteoblast apoptosis. Therefore, a rapid and simple spectrofluorometric method has been developed and validated for the quantitative determination of it. Methods: The procedure is based on the reaction of primary amino group of alendronate with o-phthalaldehyde (OPA) in sodium hydroxide solution. Results: The calibration graph was linear over the concentration range of 0.0-2.4 μM and limit of detection and limit of quantification of the method was 8.89 and 29 nanomolar, respectively.The enthalpy and entropy of the reaction between alendronate sodium and OPA showed that the reaction is endothermic and entropy favored (ΔH = 154.08 kJ/mol; ΔS = 567.36 J/mol K) which indicates that OPA interaction with alendronate is increased at elevated temperature. Conclusion: This simple method can be used as a practical technique for the analysis of alendronate in various samples.

A zone-fluidics (ZF) based automated fluorimetric sensor for the determination of pharmaceutically active adamantine derivatives, i.e., amantadine (AMA), memantine (MEM) and rimantadine (RIM) is reported. Discrete zones of the analytes and reagents (o-phthalaldehyde and N-acetylcysteine) mix and react under stopped-flow conditions to yield fluorescent iso-indole derivatives (λex/ λem = 340/455 nm). The proposed ZF sensor was developed and validated to prove suitable for quality control tests (assay and content uniformity) of commercially available formulations purchased from the Greek market (EU licensed) and from non-EU web-pharmacies at a sampling rate of 16 h−1. Interestingly, a formulation obtained through the internet and produced in a third—non-EU—country (AMA capsules, 100 mg per cap), was found to be out of specifications (mean assay of 85.3%); a validated HPLC method was also applied for confirmatory purposes.