The illegal addition of chemically synthesised drugs or their derivatives into foods claiming functionality poses significant public health risks. However, detecting these compounds remains challenging due to structural ambiguity and the lack of standardised comparison substance for emerging synthetic derivatives. This study describes an integrated analytical approach combining sample preparation with ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole-linear ion trap mass spectrometry (UPLC-QTrap/MS) for the screening and detection of oxyphenisatin and phenolphthalein derivatives (OAPs) in functional weight-loss foods. The addition of oxyphenisatin cyclohexanecarboxylate was confirmed in a soft candy product under the brand name "Hai Chi", although in the absence of a commercial standard, the concentration could not be established.Fragmentation patterns of specific oxyphenisatin and phenolphthalein derivatives were analysed based on collision-induced dissociation (CID) pathways in positive electrospray ionisation (ESI) mode. The method employed precursor ion-information dependent acquisition-enhanced product ion (Prec-IDA-EPI) scanning and multiple reaction monitoring (MRM) for screening and quantification. Twelve OAPs were characterised by their CID product ions, with precursor ion scanning targeting diagnostic fragments at m/z 224.1 and m/z 225.1, enabling comprehensive detection of compounds (200-800 m/z). Application of this method to 50 samples of commercial weight-loss foods led to the identification of a novel, illegally added oxyphenisatin analog in soft candy. To confirm the unknown compound, a post-hydrolysis comparison substance verification strategy was implemented, supported by high-resolution mass spectrometry (HRMS) for molecular formula confirmation.

Current society is facing the global surge in obesity rates, making people more aware of the importance of body weight control and increasing the consumption of weight-loss supplements due to their over-the-counter status. However, certain producers have intentionally adulterated supplements with prescription weight-loss drugs without label declaration, necessitating suitable analytical methods for routine analysis of illegal weight-loss compounds in health supplements. In this study, a rapid, effective, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of 11 wt-loss compounds in three supplement forms (i.e., hard capsule, soft capsule, and tea powder). A suitable analytical procedure was selected via the optimization of LC-MS/MS parameters and sample preparation conditions. The samples were ultrasonicated with methanol, and the extracts were cleaned up using dispersive solid-phase extraction with C18 and carbon sorbent. The method was validated for specificity, linearity, method detection and quantification limits, precision, and accuracy, producing good satisfaction. The method was applied to analyze 82 health supplement samples collected from the Vietnamese market, in which seven samples were found to be adulterated with at least one of the target compounds. Sibutramine, phenolphthalein, and benzylsibutramine were detected in 7/82, 5/82, and 2/82 samples with concentration ranges of 0.44-16.4, 0.54-2.14, and 0.14-1.43 mg/g, respectively. These results indicated the method applicability to the quality control of health supplements in developed and emerging countries.

A dual-mode electrical-optical nanocomposite hydrogel is developed by integrating carboxyl-modified upconversion nanoparticles (UCNPs-COOH) and quaternized chitosan (CQAS) into a polyacrylamide (PAAm) covalent network. The hydrogel exhibits high optical transparency (>90% in the visible region), excellent mechanical properties (fracture strain of 1742%, tensile strength of 0.85 MPa, toughness of 6.57 MJ/m[3]), and robust adhesion to various substrates. The synergistic covalent-noncovalent hybrid network enables efficient energy dissipation, while CQAS-enhanced dispersion of UCNPs significantly improves upconversion luminescence intensity and stability, as evidenced by prolonged fluorescence lifetime from 0.564 ms to 0.691 ms at 539 nm. Leveraging distinct electrical and optical signal transduction pathways, the hydrogel functions as a highly sensitive resistive strain sensor with multistage gauge factors up to 13.85 and excellent cyclic stability over 1200 loading-unloading cycles at 100% strain for human motion monitoring. It also serves as a ratiometric optical pH sensor over a broad range (pH 1-13) based on phenolphthalein-sensitized upconversion luminescence, with excellent repeatability. By integrating real-time resistance responses with optical readouts within a single soft material, this work demonstrates a reliable dual-mode sensing strategy for simultaneous mechanical and chemical monitoring, holding promise for wearable electronics, smart healthcare, and environment-responsive sensing systems.

A phenolphthalein-based Schiff base, 3,3-bis-{4-hydroxy-3-[(pyridine-2-ylmethylimino)-methyl]-phenyl}-3H-isobenzofuran-1-one (PAP), has been synthesized and used for selective fluorescence 'turn on' and 'turn off' sensing of Zn[2+] and PO4[3-] respectively. The limit of detection using the 3σ method for Zn[2+] is found to be 19.3 nM and that for PO4[3-] is 8.3 μM. The sensing mechanism of PAP for Zn[2+] ions has been explained by [1]H NMR, [13]C NMR, TRPL, ESI-MS, FT-IR, and DFT based calculations. Taking advantage of this fluorescence 'on-off' behavior of PAP in the sequential presence of Zn[2+] and PO4[3-] a two input fuzzy logic (FL) operation has been constructed. The chemosensor PAP can thus act as a metal ion and anion responsive molecular switch, and its corresponding emission intensity is used to mimic numerous FL functions. To replace various expensive, time-consuming experimental procedures, we implemented machine learning soft computing tools, such as fuzzy-logic, artificial neural networks (ANNs), and adaptive neuro-fuzzy inference systems (ANFIS), to correlate as well as predict the fluorescence intensity in the presence of any equivalent ratio of Zn[2+] and PO4[3-]. The statistical performance measures (MSE and RMSE, for example) show that the projected values of the cation and anion sensing data by the ANFIS network are the best and closer to the experimental values.

A C2-symmetric internally conjugated 1,3-dialkyne system 5, containing phenolphthalein as a fluorophore and ferrocene as a redox moiety, has been synthesized via a microwave-assisted synthetic procedure. Compound 5 was synthesized by Cu-catalyzed Glaser-Hay coupling using a microwave reactor in neat condition for the first time. Compound 5 was found to be highly selective toward Fe3+, Cu2+, and Hg2+ ions via multichannels. Interestingly, Fe3+ and Cu2+ ions simply promote the oxidation of ferrocene unit to ferrocenium ion without binding to the receptor, whereas Hg2+ binds with the receptor 5 (ΔE1/2 = 71 mV). The oxidation and binding phenomena were investigated by optical and electrochemical analyses. Furthermore, the binding site of Hg2+ ion with our designed probe was confirmed by 1H, 13C NMR and IR titrations, which indicated that conjugated dialkyne unit interacts with Hg2+ ion by a favorable soft-soft interaction. Both receptor 5 and its metal complex, [5·2Hg2+], are stable in the physiological pH range (pH = 6-7) and thermally stable up to 78 °C. The experimental results of metal binding have been further supported by quantum chemical calculations (DFT), which explore the favorable geometry of the free ligand as well as its Hg2+ complex.

The ring-opening reaction of phenolphthalein (PP) crystals under hydrostatic pressure provided by using a diamond anvil cell (DAC) is described in this paper for the first time. The color of the crystals changed into red from colorless visibly. The ring-opening threshold pressures could be adjusted by changing the substituent groups. Mechanochromic responses under hydrostatic pressure could also be achieved in polymer blends, which contributes to their practical applications.

Highly alkaline hydrogels that allow the restoration of alkaline buffer in cementitious materials can be obtained from diallyldimethylammonium hydroxide. The latter must be prepared in dilute solutions and polymerised at ambient temperatures in order to avoid decomposition. Using methacrylamide as a neutral co-monomer capable of forming hydrogen bonds, the rheological properties of the gels can be adjusted over a wide range; e.g. the viscosity increases a thousandfold from 0.35 Pa s to >350 Pa s by using 10 mol% methacrylamide. For the proof of principle experiments, gels with 9 mol% methacrylamide were used, which contain approx. 1.6 mol hydroxide ions per kg gel. Ion exchange between this and a neutral chloride containing gel provided an apparent diffusion coefficient of 4.12 × 10-7 m2 s-1 for the hydroxide ions and confirmed the transport of chloride ions into the alkaline gel. The re-alkalisation was tested on fully carbonated mortar prisms made from Portland cement. Re-alkalisation of the mortar was confirmed by the phenolphthalein test according to DIN EN 14630:2007-01 and by a control experiment with pure calcium carbonate using IR spectroscopy.

An automatic sequential injection system, combining monosegmented flow analysis, sequential injection analysis and sequential injection titration is proposed for acidity determination. The system enables controllable sample dilution and generation of standards of required concentration in a monosegmented sequential injection manner, sequential injection titration of the prepared solutions, data collecting, and handling. It has been tested on spectrophotometric determination of acetic, citric and phosphoric acids with sodium hydroxide used as a titrant and phenolphthalein or thymolphthalein (in the case of phosphoric acid determination) as indicators. Accuracy better than |4.4|% (RE) and repeatability better than 2.9% (RSD) have been obtained. It has been applied to the determination of total acidity in vinegars and various soft drinks. The system provides low sample (less than 0.3 mL) consumption. On average, analysis of a sample takes several minutes.