Abstract: This study introduces a novel method for detecting free glycidol and total free monochloropropanediol (MCPD) in fish and krill oil. Before analysis on high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS), p-(dimethylamino)phenol was used for derivatization of these compounds, enabling the sensitive determination of these contaminants. The sample preparation procedure includes a simple, efficient pretreatment using NaCl aqueous solution extraction and C18 sorbent cleanup (for demulsification), distinguishing glycidol from MCPD under varied reaction conditions for derivatization (weak acidic and strong alkaline aqueous environments). This approach shows broad linearity from 1 to at least 256 ng·mL−1, improved sensitivity compared to standard GC-MS methods, with the limit of detection (LOD) and limit of quantification (LOQ) for MCPD and glycidol in both oil samples verified at 0.5 ng·mL−1 and 1 ng·mL−1, respectively. Different from previous HPLC-MS methods for direct detection of glycidol esters or MCPD esters, this is the first HPLC-MS method used for the detection of free glycidol and total free MCPD in edible oil. Furthermore, this method can be potentially developed for glycidol or monochloropropane diol esters, which is similar to the current official methods adopted for indirect detection of these contaminants in different food matrices. Application of this detection method to real dietary supplements (fish oil and krill oil) revealed MCPD residues in fish oil (maximum detected: 32.78 ng·mL−1) and both MCPD (maximum detected: 2767.3 ng·mL−1) and glycidol (maximum detected: 22.2 ng·mL−1) in krill oil, emphasizing its effectiveness and accuracy for assessing contamination in these supplements.

Abstract: High performance liquid chromatography coupled with post-column derivatization is used for increasing the sensitivity and selectivity of the desirable analytes after the chromatographic separation. The transformation of the analytes can be conducted through the addition of a suitable reagent in the eluted stream or the ultraviolet irradiation of the eluted analytes, forming detectable derivatives for ultraviolet or fluorescence detectors. This review focuses on the developed methods using high performance liquid chromatography coupled with post-column derivatization for the determination of substances in food samples during the last two decades. The significance of the determination of each analyte in foods and the existing guidelines in each case are discussed. Preparation of the samples and the analytical methods are commented. For each analyte, official methods and commercially available systems and reagents are mentioned, as well.

Abstract: Mass spectrometry (MS) imaging of lipids in tissues with high structure specificity is challenging in the effective fragmentation of position-selective structures and the sensitive detection of multiple lipid isomers. Herein, we develop an MS3 imaging method for the simultaneous analysis of phospholipid C═C and sn-position isomers by on-tissue photochemical derivatization, nanospray desorption electrospray ionization (nano-DESI), and a dual-linear ion trap MS system. A novel laser-based sensing probe is developed for the real-time adjustment of the probe-to-surface distance for nano-DESI. This method is validated in mouse brain and kidney sections, showing its capability of sensitive resolving and imaging of the fatty acyl chain composition, the sn-position, and the C═C location of phospholipids in an MS3 scan. MS3 imaging of phospholipids has shown the capability of differentiation of cancerous, fibrosis, and adjacent normal regions in liver cancer tissues.

Abstract: Over the years, monitoring the quality of the environment, food, and human health has emerged as a fundamental objective of scientific investigation. Various analytical techniques have been devised and continually refined to ensure a high standard of living. Among these methods, dispersive liquid–liquid microextraction (DLLME) stands out as a widely used approach to conduct analytical evaluations and pre-concentrations of chemical compounds. This review provides an account of the evolution of DLLME over the past five years (2018–2023). The Scopus search engine was used to search for scientific articles. The selection of relevant articles was carried out according to the criteria described below. Emphasis was placed on the evolution that DLLME has undergone over the years by integrating it with other pre-concentration methods in order to amplify the concentration factor and improve analytical precision. Factors such as solvent dispersion and extraction, dispersion formation, and the recovery of the solvent containing the extracted analytes were examined. Additionally, derivatization systems were evaluated to refine both qualitative and quantitative analysis. These efforts aim to introduce methods that are safe for operators, environmentally friendly, and economical. This review evaluates the advantages and disadvantages displayed by the evolution of this technique in the phases before, during, and after its application.

Abstract: Abstract Protein kinase C is a family of kinases that play important roles in carcinogenesis. Medicinal plants from Plectranthus spp. (Lamiaceae) are a well-known source of interesting abietanes, such as 7α-acetoxy-6β-hydroxyroyleanone ( Roy ). This study aimed to extract and isolate Roy from P. grandidentatus Gürke, comparing two extraction methods (CO 2 supercritical and ultrasound-assisted acetonic extraction), and design new royleanone derivatives for PKC modulation focusing on breast cancer therapy. The concentration of Roy in the extracts was determined by HPLC–DAD. The supercritical extraction method yielded 3.6% w/w, with the presence of 42.7 μg mg −1 of Roy (yield of 0.13%), while ultrasound-assisted acetonic extraction yielded 2.3% w/w, with the presence of 55.2 μg mg −1 of Roy (yield of 0.15%). The reactivity of Roy was investigated aiming at synthetizing new ester derivatives through standard benzoylation and esterification reactions. The benzoylated ( Roy-12-Bz ) and acetylated ( Roy-12-Ac ) derivatives in the C12 position were consistently prepared with overall good yields (33–86%). These results indicate the 12-OH position as the most reactive for esterification, affording derivatives under mild conditions. The reported di-benzoylated ( RoyBz ) and di-acetylated ( RoyAc ) derivatives were also synthesized after increasing the temperature (50 °C), reaction time, and using an excess of reagents. The cytotoxic potential of Roy and its derivatives was assessed against breast cancer cell lines, with RoyBz emerging as the most promising compound. Derivatization at position C-12 did not offer advantages over di-esterification at positions C-12 and C-6 or over the parent compound Roy and the presence of aromatic groups favored cytotoxicity. Evaluation of royleanones as PKC-α, βI, δ, ε, and ζ activators revealed DeRoy ’s efficacy across all isoforms, while RoyPr showed promising activation of PKC-δ but not PKC-ζ, highlighting the influence of slight structural changes on isoform selectivity. Molecular docking analysis emphasized the importance of microenvironmental factors in isoform specificity, underscoring the complexity of PKC modulation and the need for further exploration.

Abstract: A simple, economical, green, and sensitive spectrofluorimetric method was developed for the determination of the cyclic lipopeptide antibiotic daptomycin (DPT). The method is based on the sensitizing effect of the cationic surfactant cetyltrimethylammonium bromide (CTAB) on the weak fluorescent signal of DPT. After excitation at 373 nm, DPT-CTAB fluoresces at a maximum intensity of 458 nm. Under the optimized conditions, the method exhibits linearity over the concentration range of 0.50–10.0 μg/mL with a detection limit down to 0.11 μg/mL. The study revealed excellent selectivity towards DPT in the presence of the co-administered drugs. The proposed method was able to determine DPT in its commercial vials, and the results were comparable to those obtained by the reported method. The high sensitivity of the developed method allowed its estimation in water and biological fluids (spiked plasma and urine samples) with high % recoveries (95.89–105.99%). DPT was successfully determined in rat plasma after intra-peritoneal administration, and the method was applied for the calculation of its pharmacokinetic parameters (Cmax, t1/2, tmax, and AUC) in rat plasma. Comparison with the reported methods reveals many benefits of the proposed spectrofluorimetric method, such as greenness, simplicity, sensitivity, and reliability. Finally, different recent assessment tools confirmed the greenness and whiteness of the proposed method.

Abstract: Hyaluronic acid (HA) possesses unique biological properties that bring many biomedical applications. Nanocomposite of HA has the potential to release the drug at the overexpression of CD44 receptor for tumor growth inhibition. Properties of HA and different forms of CD44 receptor with their effect in drug delivery have discussed in this article. This article briefly discusses preparation, purification, characterization and commercial production of HA derivatives. Number of preparation methods of HA nanocomposites with their advantages and disadvantages and similarities and dissimilarities among them also included broadly in this article. Various HA nanoforms like HA nanogels, HA nanoparticles, carbon based HA nanostructures and HA nano-fibers also added to give the elaborated dimensions to the readers. Most importantly the inclusion of HA based nanocomposites as drug delivery vehicle for tumor treatment will give the future course of research plan for the researchers. The whole manuscript majorly focuses on the role of HA in its anti-tumor activity.

Abstract: Enantioselective three-component difunctionalization of alkenes with boron reagents represents an attractive strategy for assembling three-dimensional chiral organoboron compounds. However, regio- and enantiocontrol comprise the pivot challenges in these transformations, which predominantly require the use of activated conjugated alkenes. Herein, by utilizing various carbonyl directing groups, including amides, sulfinamides, ketones, and esters, we succeed in realizing a nickel-catalyzed 1,2-borylalkynylation of unactivated alkenes to enable the simultaneous incorporation of a boron entity and an sp-fragment across the double bond. The products contain boryl, alkynyl, and carbonyl functional groups with orthogonal synthetic reactivities, offering three handles for further derivatization to access valuable intermediates. The utility of this ligand-enabled asymmetric protocol has been highlighted through the late-stage decoration of drug-relevant molecules.

Abstract: The biologically important thiols (cysteine, homocysteine, N-acetyl cysteine, and glutathione) are key species in redox homeostasis, and there is a clinical need to measure them rapidly, accurately, and simultaneously at low levels in complex biofluids. The solution to the challenge presented here is based on a new derivatizing reagent that combines a thiol-selective unit to optimize the chemical transformation and a precharged pyridinium unit chosen to maximize sensitivity in mass spectrometry. Derivatization is performed simultaneously with ionization ("reactive ionization"), and mass spectrometry is used to record and characterize the thiol reaction products. The method is applicable over the concentration range from 1 μM to 10 mM and is demonstrated for 25 blood serum, 1 plasma, and 3 types of tissue samples. The experiment is characterized by limited sample preparation (<4 min) and short analysis time (<1 min). High precision and accuracy (both better than 8%) are validated using independent HPLC-MS analysis. Cystine-cysteine redox homeostasis can be monitored by introducing an additional reduction step, and the accuracy and precision of these results are also validated by HPLC-MS.

Abstract: Abstract 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.

Abstract: Fingolimod is the immune-suppressive medication, that largely used for multiple sclerosis treatment, thought to be the most prevalent inflammatory condition affecting the central nervous system (CNS). Here in, a second spectrofluorimetric method was advanced for quantifying of fingolimod in pharmaceutical formulation and spiked human plasma. That method depends on fluorescence derivatization of fingolimod with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) at 75°C in a (pH 9) of borate buffer to produce a fluorescent derivative which can be detected at 540 nm afterwards excitation at 475 nm. The method has been validated using international conference of harmonization (ICH criteria), and it demonstrated linearity in a range of 1–100 ngmL−1. The proposed method was applied precisely and accurately for quantifying fingolimod within pharmaceutical formulation and spiking human plasma without any interferences. The proposed method was more sensitive, about six folds of intensity of the reported spectrofluorometric method and greenness comparison was done only on the proposed method . Moreover, the method's sustainability was evaluated and compared to the published method using two greenness assessment tools termed analytical eco-scale and Analytical GREENness (AGREE). That findings suggest that the method is more sustainable than the published method.

Abstract: In neuroscience research, chiral metabolomics is an emerging field, in which D-amino acids play an important role as potential biomarkers for neurological diseases. The targeted chiral analysis of the brain metabolome, employing liquid chromatography (LC) coupled to mass spectrometry (MS), is a pivotal approach for the identification of biomarkers for neurological diseases. This review provides an overview of D-amino acids in neurological diseases and of the state-of-the-art strategies for the enantioselective analysis of chiral amino acids (AAs) in biological samples to investigate their putative role as biomarkers for neurological diseases. Fluctuations in D-amino acids (D-AAs) levels can be related to the pathology of neurological diseases, for example, through their role in the modulation of N-methyl-D-aspartate receptors and neurotransmission. Because of the trace presence of these biomolecules in mammals and the complex nature of biological matrices, highly sensitive and selective analytical methods are essential. Derivatization strategies with chiral reagents are highlighted as critical tools for enhancing detection capabilities. The latest advances in chiral derivatization reactions, coupled to LC-MS/MS analysis, have improved the enantioselective quantification of these AAs and allow the separation of several chiral metabolites in a single analytical run. The enhanced performances of these methods can provide an accurate correlation between specific D-AA profiles and disease states, allowing for a better understanding of neurological diseases and drug effects on the brain.

Abstract: The performance of cellulose-based materials is highly dependent on the choice of solvent systems. Exceptionally, cellulose dissolution and derivatization by efficient solvent have been considered as a key factor for large-scale industrial applications of cellulose. However, cellulose dissolution and derivatization often requires harsh reaction conditions, high energy consumption, and complex solubilizing, resulting in environmental impacts and low practical value. Here we address these limitations by using a low-temperature oxalic acid/sulfuric acid solvent to enable cellulose dissolution and derivatization for high-performance cellulose films. The dissolution and derivatization mechanism of the mixed acid is studied, demonstrating that cellulose is firstly socked by oxalic acid, then more hydrogen bonds ionized by sulfuric acid break cellulose chain, and finally the esterification reaction between oxalic acid and cellulose is catalyzed by sulfuric acid. Solutions containing 8 %-10 % cellulose are obtained and can be stored for a long time at -18 °C without significant degradation. Moreover, the cellulose film exhibits a higher tensile strength of up to 66.1 MPa, thermal stability, and degree of polymerization compared to that fabricated by sulfuric acid. These unique advantages provide new paths to utilize renewable resources for alternative food packaging materials at an industrial scale.

Abstract: A novel analytical method for the simultaneous gas chromatography-mass spectrometry (GC-MS) determination of methionine and selenomethionine in food samples is described. Samples were digested with methanesulfonic acid in a closed vessel without the need for reflux. A single step derivatization using triethyloxonium tetrafluoroborate was optimized for the conversion of the analytes into their ethyl derivatives, followed by their extraction with hexane and GC-MS analysis.. This derivatization approach was simpler and/or safer with respect to current methods based on alkyl chloroformate or silylating reagents and it yielded very clean chromatography. A design of experiment approach, based on an open source chemometric software, was used to optimize the experimental conditions. When analysis of a 1 mL volume of aqueous standard was performed, detection limits of 1 ng/g methionine and 10 ng/g for selenomethionine were obtained. The method was validated by analysis of a selenized yeast Certified Reference Material NRC SELM-1.

Abstract: BACKGROUND Personalized medicine is a rapidly revolving field that offers new opportunities for tailoring disease treatment to individual patients. The main idea behind this approach is to carefully select safe and effective medications and treatment plant based on each patient's unique pharmacokinetic profile. Isoniazid is a first-line anti-tuberculosis drug that has interindividual variability in its metabolic processing, leading to significant differences in plasma concentrations among patients receiving equivalent doses. This variability necessitates the creation of individualized treatment regimens as part of personalized medicine to achieve more effective therapy. RESULTS In this work, a deep eutectic solvent-based liquid-liquid microextraction approach for the separation and determination of isoniazid in human plasma by high-performance liquid chromatography with UV-Vis detection was developed for the first time. A new natural deep eutectic solvent based on thymol as a hydrogen bond donor and 4-methoxybenzaldehyde as a hydrogen bond acceptor was proposed as the extraction solvent. The developed microextraction procedure assumed two simultaneous processes during the mixing of the sample and extraction solvent: the derivatization of the polar analyte in the presence of 4-methoxybenzaldehyde (component of the natural deep eutectic solvent) with the formation of a hydrophobic Schiff base (1); mass transfer of the Schiff base from the sample phase to the extraction solvent phase (2). Under optimal conditions, the limits of detection and quantification were 20 and 60 μg L-1, respectively. The RSD value was <10 %, the extraction recovery was 95 %. SIGNIFICANCE In this work, the possibility of isoniazid derivatization in the natural deep eutectic solvent phase with the formation of the Schiff base was presented for the first time. The approach provided the separation and preconcentration of polar isoniazid without the use of expensive derivatization agents and solid-phase extraction cartridges. The formation of the Schiff base was confirmed by mass spectrometry.

Abstract: Detection of acrylamide in processed foods has been an intensive area of research after the discovery of acrylamide in thermally processed foods. The methods developed so far are mainly based on mass spectrometry as the determinative technique for better identification of acrylamide, coupled with a chromatographic step either by liquid chromatography or gas chromatography after derivatization, or in a few cases analysis of the compound directly. Various sample preparation procedures have been applied so far due to the diversity of sample matrices. In the analysis of acrylamide, the first step is to obtain a well-represented homogeneous sample. Acrylamide is not distributed homogeneously in foods, but it is concentrated on the surface. Because of its high polarity, water and polar organic solvents are commonly used to extract acrylamide from foods. Extraction conditions appear to be the most critical parameter in sample preparation. Single-stage extraction has been extensively applied to extract acrylamide from solid food matrices using slight differences in solvent type, solvent-to-sample ratio, extraction time, and temperature. Multiple-stage extraction using water or methanol has been shown to improve the extraction yield of acrylamide for different matrices. Most cleanup procedures consist of the combination of several solid-phase extractions to limit matrix effects, and to achieve low limits of detection. Bromination has been the most widely applied derivatization procedure for the determination of acrylamide using gas chromatography techniques. However, care should be taken during bromination because of the handling of hazardous chemicals such as bromine.

Abstract: Per- and polyfluoroalkyl substances (PFAS) have caused widespread environmental concern in recent years. Among them, the levels of perfluoroalkane sulfonyl fluorides (PFASFs) in the environment have rarely been reported due to the lack of sensitive analytical methods. Herein, a novel liquid chromatography-microwave plasma torch ionization-mass spectrometry (LC-MPTI-MS) technique was designed for the direct analysis of PFASFs in the environment. The collaborative action of reactive oxygen species (such as hydroxyl radicals) and the elevated temperature within the ambient MPTI environment results in the replacement of the fluorine atom in sulfonyl fluoride by oxygen, leading to the detection of perfluoroalkanesulfonic acid (PFSA) ions by MS. Concurrently, LC was employed to separate other PFSAs that are present in the environment. Three PFASFs exhibited good linearity within the range of 1-500 μg/L with R2 > 0.994. The limit of detections (LODs) and the limit of quantifications (LOQs) were measured at 39.32-87.87 and 131.07-292.90 ng/L, respectively. The method was utilized for the direct detection of spiked perfluorooctane sulfonyl fluoride (PFOSF) in wastewater with recoveries of 77.16 to 124.81%. Our approach circumvents the laborious process of chemical derivatization and is anticipated to serve as a robust tool for determining the levels and behaviors of PFASFs in the environment.

Abstract: This work highlights stellane's cage stability and derivatization opportunities. Using modern synthesis protocols, a di-verse range of building blocks were synthesized. Stellane's reactivity and chemical tolerance were rigorously evaluated across different reaction systems, demonstrating its promise as a bio-isosteric scaffold. It can be utilized in scaffold-based molecular design and offers topological precision superiority over existing ortho-isosteres, as well as mono-substituted benzene mimetics, holding the potential to become a robust platform for future medicinal chemistry studies.

Abstract: Saccharides are a sort of ubiquitous and vital molecules within the whole life. However, the application of saccharides analysis with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is restricted by their low ionization efficiency and the instability of the sialic acid fraction. Derivatization strategy based on nonreductive amination provides a good solution, however, this is often time consuming and may result in sample loss due to removal of excessive derivatization reagents. Herein, hydralazine (HZN) was utilized as a reactive matrix for labeling reducing saccharides directly on MALDI target which eliminated tedious sample preparation and avoided sample loss. After optimization, effective and reproducible on-MALDI-target derivatization of neutral and acidic saccharides was achieved in both positive and negative modes. Compared with 2,5-dihydroxybenzoic acid (DHB) and 9-aminoacridine (9-AA), HZN improved the detection sensitivity of reducing saccharides and provided more abundant fragment ions in MS/MS analysis. Moreover, 26 kinds of neutral glycans and 5 kinds of sialic glycans were identified from ovalbumin (OVA) and bovine fetuin, respectively. Combined with the statistical models, this strategy could be used to distinguish and predict samples of 6 brands of beer, and discriminate 2 kinds of beer fermentation modes. In addition, HZN was applied for quantitative analysis of glucose in urine samples, and the obtained urine glucose concentrations of diabetic patients were consistent with the clinical test results, showing the potential of qualitative and quantitative analysis of reducing saccharides in complex samples.

Abstract: Estrogens and their analogues can cause harm to human health through the food chain. Ten estrogens in different milk samples were directly extracted by amphiphilic divinylbenzene/N-vinyl-2-pyrrolidone (DVB/NVP)-Fe

Abstract: This review paper critically examines the current state of research concerning the analysis and derivatization of aldehyde, aromatic hydrocarbons and carboxylic acids components in foods and drinks samples, with a specific focus on the application of Chromatographic techniques. These diverse components, as vital contributors to the sensory attributes of food, necessitate accurate and sensitive analytical methods for their identification and quantification, which is crucial for ensuring food safety and compliance with regulatory standards. In this paper, High-Performance Liquid Chromatography (HPLC) and Gas Chromatographic (GC) methods for the separation, identification, and quantification of aldehydes in complex food matrices were reviewed. In addition, the review explores derivatization strategies employed to enhance the detectability and stability of aldehydes during chromatographic analysis. Derivatization methods, when applied judiciously, improve separation efficiency and increase detection sensitivity, thereby ensuring a more accurate and reliable quantification of aldehyde aromatic hydrocarbons and carboxylic acids species in food samples. Furthermore, methodological aspects encompassing sample preparation, chromatographic separation, and derivatization techniques are discussed. Validation was carried out in term of limit of detections are highlighted as crucial elements in achieving accurate quantification of compounds content. The discussion presented by emphasizing the significance of the combined HPLC and GC chromatography methods, along with derivatization strategies, in advancing the analytical capabilities within the realm of food science.

Abstract: The identification and quantitation of plasmalogen glycerophospholipids is challenging due to their isobaric overlap with plasmanyl ether-linked glycerophospholipids, susceptibility to acid degradation, and their typically low abundance in biological samples. Trimethylation enhancement using diazomethane (TrEnDi) can be used to significantly enhance the signal of glycerophospholipids through the creation of quaternary ammonium groups producing fixed positive charges using 13C-diazomethane in complex lipid extracts. Although TrEnDi requires a strong acid for complete methylation, we report an optimized protocol using 9.6 mM HBF4 with the subsequent addition of a buffer solution that prevents acidic hydrolysis of plasmalogen species and enables the benefits of TrEnDi to be realized for this class of lipids. These optimized conditions were applied to aliquots of bovine liver extract (BLE) to achieve permethylation of plasmalogen lipids within a complex mixture. Treating aliquots of unmodified and TrEnDi-derivatized BLE samples with 80% formic acid and comparing their liquid chromatography mass spectrometry (LCMS) results to analogous samples not treated with formic acid, enabled the identification of 29 plasmalogen species. On average, methylated plasmalogen species from BLE demonstrated 2.81-fold and 28.1-fold sensitivity gains over unmodified counterparts for phosphatidylcholine and phosphatidylethanolamine plasmalogen species, respectively. Furthermore, the compatibility of employing 13C-TrEnDi and a previously reported iodoacetalization strategy was demonstrated to effectively identify plasmenyl-ether lipids in complex biological extracts at greater levels of sensitivity. Overall, we detail an optimized 13C-TrEnDi derivatization strategy that enables the analysis of plasmalogen glycerophospholipids with no undesired cleavage of radyl groups, boosting their sensitivity in LCMS and LCMS/MS analyses.

Abstract: The combination of post-column derivatization (PCD) and liquid chromatography (LC) has become a promising technique for enhancing detection sensitivity and selectivity, while simultaneously facilitating rapid and automated analysis. This paper presents a comprehensive review of PCD techniques spanning from 2013 to 2023, focusing on LC-UV-Vis/fluorescence spectrometry and LC-mass spectrometry detection methods. It encompasses an array of PCD methods, including chemical, photochemical, and electrochemical derivatization, as well as post-column complexation. This review delves deeply into key areas, exploring the underlying principles of derivatization, examining the current applications of classical PCD methods, and shedding light on emerging derivatization reactions. The review also provides remarks and insights into future directions, offering a perspective on the evolving landscape of the field. The overarching goal is to equip researchers with innovative ideas and strategies for PCD, thereby enhancing the practical application and utility of this technology in scientific research.

Abstract: Abstract This study describes the development of a reliable and linear analytical method for precisely determining dimethylamine impurity in N , N ‐dimethylformamide solvent utilizing a benzoyl chloride derivatization reagent and a gas chromatography mass spectrometer. Benzoyl chloride was used to derivatize dimethylamine. At normal temperature, benzoyl chloride combined with dimethylamine, producing N , N ‐dimethylbenzamide. This method separated N , N ‐dimethylbenzamide using Rtx‐5 amine (30 m × 0.32 mm × 1.50 μm) as the stationary phase, helium as the carrier gas, argon as the collision gas, and methanol as the diluent. The column flow rate was 2 mL/min. The retention time of N , N ‐dimethylbenzamide was determined to be 8.5 min. Precision, linearity, and accuracy were tested using ICH Q2 (R2) and USP<1225> guidelines. The percentage coefficient of variation (CV) for N , N ‐dimethylbenzamide in the system suitability parameter was 1.1%. The correlation coefficient of N , N ‐dimethylbenzamide was found to be >0.99. In the method precision parameter, the % CV for N , N ‐dimethylbenzamide was found to be 1.9%, whereas the % CV for N , N ‐dimethylbenzamide was 1.2% in intermediate precision. The percentage recovery of N , N ‐dimethylbenzamide was determined to be between 80% and 98%.

Abstract: Soy sauce has a rich base of non-volatile substances, but existing studies are insufficient. This study analyzed the metabolites of 19 Chinese commercial soy sauces by UPLC-Orbitrap-MS/MS and GC-Tof-MS derivatization, and detected 674 and 230 kinds of substances, respectively, that could be grouped into 12 different classes of compounds, such as peptides, amino acid derivatives, organic acids, sugars, sugar alcohols, amino acids and so on. For the first time, 215 dipeptides and 91 amino acid derivatives in soy sauce were analyzed in detail and systematically from the perspective of composition and amino acid structure. The flavor profile of soy sauce was obtained by electronic tongue analysis, and orthogonal projections to latent structures (OPLS), random forest (RF), correlation were used to screen potential compounds associated with umami. The intersection of the three methods yielded 9 substances, including 4 reported umami-taste compounds, i.e., Glu, Fru-Glu, Inosine 5'prime-monophosphate (IMP) and Arg-Ser, as well as 5 others that may potentially contribute to umami or be associated with umami-taste producing microorganisms, including His-Asn and Homoserine lactone. This study will advance the understanding of soy sauce metabolites, and provide an in-depth reference for dipeptides and amino acid derivatives in soy sauce.

Abstract: Abstract The continuous introduction of micropollutants into the environment through livestock farming, agricultural practices, and wastewater treatment is a major concern. Among these pollutants are synthetic sulfonamide antibiotics such as sulfamethoxazole, which are not always fully degraded and pose a risk of fostering antimicrobial resistance. It is challenging to assess the degradation of sulfonamides with conventional concentration measurements. This study introduces compound-specific isotope analysis of nitrogen isotope ratios at natural abundances by derivatization-gas chromatography hyphenated with isotope ratio mass spectrometry (derivatization-GC-IRMS) as a new and more precise method for tracing the origin and degradation of sulfonamides. Here, sulfamethoxazole was used as a model compound to develop and optimize the derivatization conditions using (trimethylsilyl)diazomethane as a derivatization reagent. With the optimized conditions, accurate and reproducible δ 15 N analysis of sulfamethoxazole by derivatization-GC-IRMS was achieved in two different laboratories with a limit for precise isotope analysis of 3 nmol N on column, corresponding to 0.253 µg non-derivatized SMX. Application of the method to four further sulfonamides, sulfadiazine, sulfadimethoxine, sulfadimidine, and sulfathiazole, shows the versatility of the developed method. Its benefit was demonstrated in a first application, highlighting the possibility of distinguishing sulfamethoxazole from different suppliers and pharmaceutical products. Graphical Abstract

Abstract: Herein, a new, direct paper-based fluorimetric method is described for the quantitative determination of glutathione (GSH) molecules in nutritional supplements. Briefly, the proposed analytical method is based on the fluorescence emission resulting from the direct and selective chemical reaction of GSH molecules with the derivatization reagent that is o-phthalaldehyde (OPA) in acidic conditions at room temperature. The intensity of the emitted fluorescence on the surface of the analytical paper devices after irradiation with a lamp at 365 nm is proportional to the concentration of GSH and is measured using a smartphone as the detector. This methodology, which is suitable for measurements in laboratories with limited resources, does not require specialized instrumentation or trained personnel. The protocol governing the proposed method is simple and easily applicable. Essentially, the chemical analyst should adjust the value of pH on the surface of the paper by adding a minimal amount of buffer solution; then, after adding a few microliters of the derivatization reagent, wait for the surface of the paper to dry and, finally, add the analyte. Subsequently, the irradiation of the sensor and the measurement of the emitted fluorescence can be recorded with a mobile phone. In the present study, several parameters affecting the chemical reaction and the emitted fluorescence were optimized, the effect of interfering compounds that may be present in dietary supplements was examined, and the stability of these paper sensors under different storage conditions was evaluated. Additionally, the chemical stability of these paper devices in various maintenance conditions was studied, with satisfactory results. The detection limit calculated as 3.3 S/N was 20.5 μmol L