Analysis Method Research Articles

A Newly Validated HPLC-DAD Method for the Determination of Ricinoleic Acid (RA) in PLGA Nanocapsules

The assessment of ricinoleic acid (RA) incorporated into polymeric nanoparticles is a challenge that has not yet been explored. This bioactive compound, the main component of castor oil, has attracted attention in the pharmaceutical field for its valuable anti-inflammatory, antifungal, and antimicrobial properties. This work aims to develop a new and simple analytical method using high-performance liquid chromatography with diode-array detection (HPLC-DAD) for the identification and quantification of ricinoleic acid, with potential applicability in several other complex systems. The method was validated through analytical parameters, such as linearity, limit of detection and quantification, accuracy, precision, selectivity, and robustness. The physicochemical properties of the nanocapsules were characterized by dynamic light scattering (DLS) to determine their hydrodynamic mean diameter, polydispersity index (PDI), and zeta potential (ZP), via transmission electron microscopy (TEM) and quantifying the encapsulation efficiency. The proposed analytical method utilized a mobile phase consisting of a 65:35 ratio of acetonitrile to water, acidified with 1.5% phosphoric acid. It successfully depicted a symmetric peak of ricinoleic acid (retention time of 7.5 min) for both the standard and the RA present in the polymeric nanoparticles, enabling the quantification of the drug loaded into the nanocapsules. The nanocapsules containing ricinoleic acid (RA) exhibited an approximate size ranging from 309 nm to 441 nm, a PDI lower than 0.2, ζ values of approximately −30 mV, and high encapsulation efficiency (~99%). Overall, the developed HPLC-DAD procedure provides adequate confidence for the identification and quantification of ricinoleic acid in PLGA nanocapsules and other complex matrices.

The Role of Social Impact Bond on Utilizing Impact Investment to Develop Asir District in Line with the Kingdom’s Vision 2030: Academics and Economists' Perspectives

The social impact bond (SIB) is a new tool for financing innovative social projects and impact investment. This financial method has since been introduced (Warner,2013) in the whole world. SIBs are a strategically double-edged policy tool and policymakers should be prudent about SIBs because of legitimate convolution and management, responsibility, and precision (Tan, et al., 2021). The current study aims to explore the perspectives of academics and economists on the role played by Social Impact Bond in utilizing impact investment to develop Asir district in line with the Kingdom’s Vision 2030. The descriptive-analytical method was adopted by the researcher in this study to describe the responses of the study sample to its topic. Some indicators of the mean, standard deviation, and relative significance of each item of the study area were employed. This paper is eminently reflective, and the methodology on relies on an analytical research method. In addition, the results of 100 brief investigations collected in the Kingdom of Saudi Arabia are summed up to show the role played by Social Impact Bond in using Impact Investment and the circular economy's principles by businesses at the micro-level is underexplored in the literature. The findings of the study revealed that 82.3% of Academics and Economists perceive that the role played by social impact bond on utilizing impact investment to develop Asir district in line with the Kingdom’s Vision 2030 is effective, and the percentage of approval on the domain was high in terms of the mean of 3.86. Also, the study showed that Academics and Economists perceive Social impact bonds to include a wide range of interested parties such as Saudi governmental bodies, and investors to work together significantly to set up a SIB has many advantages as the mean hits 4.48 with a percentage of97.8 %. In light of the results, the study recommends decision-making bodies assess carefully what is the value added for applying social impact bonds.

Correlating plasma protein profiles with symptomatology and treatment response in acute phase and early remission of major depressive disorder

ObjectivesThis study aimed to explore the relationship between plasma proteome and the clinical features of Major Depressive Disorder (MDD) during treatment of acute episode.MethodsIn this longitudinal observational study, 26 patients hospitalized for moderate to severe MDD were analyzed. The study utilized Liquid Chromatography with Tandem Mass Spectrometry (LC-MS/MS) alongside clinical metrics, including symptomatology derived from the Montgomery-Åsberg Depression Rating Scale (MADRS). Plasma protein analysis was conducted at the onset of acute depression and 6 weeks into treatment. Analytical methods comprised of Linear Models for Microarray Data (LIMMA), Weighted Correlation Network Analysis (WGCNA), Generalized Linear Models, Random Forests, and The Database for Annotation, Visualization and Integrated Discovery (DAVID).ResultsFive distinct plasma protein modules were identified, correlating with specific biological processes, and uniquely associated with symptom presentation, the disorder’s trajectory, and treatment response. A module rich in proteins related to adaptive immunity was correlated with the manifestation of somatic syndrome, treatment response, and inversely associated with achieving remission. A module associated with cell adhesion was linked to affective symptoms and avolition, and played a role in the initial episodes and treatment response. Another module, characterized by proteins involved in blood coagulation and lipid transport, exhibited negative correlations with a variety of MDD symptoms and was predominantly associated with the manifestation of psychotic symptoms.ConclusionThis research points to a complex interplay between the plasma proteome and MDD’s clinical presentation, suggesting that somatic, affective, and psychotic symptoms may represent distinct endophenotypic manifestations of MDD. These insights hold potential for advancing targeted therapeutic strategies and diagnostic tools.LimitationsThe study’s limited sample size and its naturalistic design, encompassing diverse treatment modalities, present methodological constraints. Furthermore, the analysis focused on peripheral blood proteins, with potential implications for interpretability.

The Electrochemistry of Nitro Compounds from a Bibliometric Approach

Abstract The heterocyclic and aromatic nitro compounds are industrially and commercially important chemicals, used in drugs, explosives, pesticides, and dyes. Despite their economic importance, the advent of these chemicals also brought serious human health and environmental problems due to their toxic characteristics as contaminants and pollutants. The nitro group is catalyzed in vivo by nitroreductases promoting a six-electron reduction to form sequentially the nitro radical anion, nitroso-, N-hydroxylamino and amino-functional groups. These reactions can be electrochemically reproduced, involving the development of analytical methods and electrochemical sensors, degradation and removal of organic compounds in effluents, corrosion studies, and studies of action mechanism of drugs on DNA bases. In this sense, a bibliometric analysis has been performed based on the Web of Science Core Collection in conjunction with VOSviewer software for generating network visualizations. This research covered the database until 2023, describing the main research areas and the annual publication trends, the collaborations and contributions among countries and research institutions, in addition to identifying the most cited articles, hotspots, and the analysis of evolution and relevance of keywords. This investigation made it possible to recognize the main research focuses and what is under development, providing a comprehensive overview on electrochemistry of nitro compounds.

In Situ Photoelectrodeposited Polyaniline on Ti‐Doping Hematite For Highly Selective Photoelectrochemical Oxygen Demand Determination

AbstractChemical Oxygen Demand (COD), as a detection indicator of water pollution, is of particular importance in assessing organic pollution in water. Furthermore, accurate and simple measuring COD methods are essential for water quality assessment and pollution control. However, the photoelectrochemical oxygen demand (PECOD) measurement, as one of the measuring COD methods, is affected by the reaction of water splitting, which is one of the hindrances to the commercialization of the analytical method of the PeCOD measurement. Hence, to overcome this challenge, a new PANI/Ti:Fe2O3 photoanode is constructed by hydrothermal and photoelectrochemical (PEC) deposition methods and investigated their optical properties and photoactivity. Under optimization conditions, it is discovered that the oxidation of organic compounds produces a net steady‐state current (inet) is directly proportional to COD concentration, with a detection limit of 1 mM glucose solution and a wide linear detection range of 1–78.125 mM, which is suitable for high concentration of glucose detection. As has been noted, PANI/Ti:Fe2O3 photoanode overcomes the obstacles to the practical application and eventual commercialization of the PECOD technology.

Dispersion compensation design of high-density stacking RFSS absorbers for wideband applications

Abstract A dispersion compensation design absorber realized by high-density stacking resistive frequency selective surface (RFSS) is proposed for wideband applications. Firstly, the quantitative relationship between the equivalent impedance of RFSS and the permittivity of the effective media is constructed with the help of the transmission matrix method. The dispersion regulation of permittivity is achieved by changing the pattern and the square resistance of RFSS. In terms of absorber design, a uniform absorber with dispersion manipulation is developed as a precursor absorber. The uniform absorber has an absorption performance better than −8.5 dB above 2 GHz at normal incidence. The loss mechanism is analyzed in detail by electric field distribution and surface power loss density distribution, indicating that the uniform design cannot achieve thickness saving when extending to low frequency. Therefore, a dispersion compensation design absorber is proposed to extend −10 dB bandwidth to 1.64–28.8 GHz. Experiment results agree well with the simulation results, validating the analytic methods and design principles.

DNA Metabarcoding Approach as a Potential Tool for Supporting Official Food Control Programs: A Case Study

Food authentication significantly impacts consumer health and the credibility of Food Business Operators (FBOs). As European regulations mandate the verification of food authenticity and supply chain integrity, competent authorities require access to innovative analytical methods to identify and prevent food fraud. This study utilizes the DNA metabarcoding approach on meat preparations, sampled during an official control activity. It assesses animal and plant composition by amplifying DNA fragments of the 12S rRNA and trnL (UAA) genes, respectively. The results not only confirmed the declared species but also revealed undeclared and unexpected taxa in products labelled as containing a single animal species and various unspecified plant species. Notable findings such as the presence of Murinae, Sus scrofa, Ovis aries, and Pisum sativum could raise public health concerns, compromise consumer choices made for ethical or religious reasons, and reflect the hygienic conditions of the processing plant. This study demonstrates that the DNA metabarcoding approach looks to be a promising support tool for official control authorities to ensure food authenticity and safety, and to develop risk profiles along the supply chain.

First evidence on the occurrence of multi-mycotoxins and dietary risk exposure to AFB1 along the cassava value chain in Uganda.

This study investigated the occurrence and distribution of multiple mycotoxins (aflatoxin B1, B2, G1, G2, fumonisins B1, B2, ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZEN), and citrinin (CIT)) in cassava products and as assessed the potential risk of aflatoxin B1 (AFB1) exposure among cassava consumers. A total of 192 samples of cassava products (96 flour and 96 chips, each with 48 samples from farmer and 48 from wholesaler) were analysed using LC/MS-MS. All positive samples irrespective of their origin (flour or chips) exhibited AFB1 levels exceeding the EU regulatory threshold of 5µg/kg. The sum of fumonisins (FB1 + FB2), ZEN, and DON were significantly (P < 0.05) higher in cassava flour (14.3µg/kg; 3.71µg/kg; 25.1µg/kg) compared to chips (6.54µg/kg; 1.25µg/kg; 0.25µg/kg), respectively. Aflatoxins G2 was not detected in any of 192 samples. Cassava flour samples from farmers exhibited significantly (P < 0.05) higher mean concentrations of AFB1 (27.1µg/kg), total aflatoxins (78.2µg/kg), and ochratoxin A (79.6µg/kg) in contrast to wholesalers, whose mean levels were notably lower at 8.91, 5.79µg/kg, and 2.44µg/kg, respectively, pointing the likely critical source of mycotoxin contamination. Cassava consumers in Northern Uganda are at a higher risk, with an estimated 2.06 cancer cases per 100,000 individuals per year compared to those in Eastern Uganda at 0.25. This study underscores the urgent need for interventions to manage aflatoxins in cassava flour, particularly at farm level in Northern Uganda. It accentuates a shift market to household-level sampling and the need for analytical methods targeting multiple mycotoxins.

Quantitative Study of Vitamin K in Plants by Pressurized Liquid Extraction and LC-MS/MS

The health-promoting properties of vitamin K stimulate the growing interest in this compound, which translates into the development of new analytical methodologies for its determination. New, more efficient methods of its isolation are sought, paying increasingly more attention to the methods within currently available extraction techniques that, owing to the optimization of the process, not only increase the extraction efficiency but are also economical and environmentally friendly. This article proposes a procedure for the extraction and analysis of one of the vitamin K vitamers, i.e., vitamin K1, using PLE and LC-MS/MS. It has been shown that the PLE technique can be optimized with a mathematical model—accelerating and reducing the costs of the extraction process—which, together with process automation, bodes well for industrial applications. The optimized process was used to extract vitamin K1 from various vegetables, showing very different contents of the test compound ranging from 1.22 to 114.30 µg/g dry weight for avocado and spinach, respectively. In addition, by showing the effect of water within the material subjected to extraction on the variable yield of vitamin K1, attention was drawn to the need to standardize the analytical methods used in assessing the quality of food products.

An Improved Method and Device for Nucleic Acid Isolation Using a High-Salt Gel Electroelution Trap.

The success of DNA analytical methods, including long-read sequencing, depends on the availability of high-quality, purified DNA. Previously, we developed a method and device for isolating high-molecular-weight (HMW) DNA for long-read sequencing using a high-salt gel electroelution trap. Here, we present an improved version of this method for purifying nucleic acids with high yield and purity from even the most challenging biological samples. The proposed method is a significant improvement over the previously published procedure, offering a simple, fast, and efficient solution for isolating HMW DNA and smaller DNA and RNA molecules. The method utilizes vertical gel electrophoresis in two nested, partially overlapping electrophoretic columns. The upper, smaller-diameter column has a thin layer of agarose gel at the bottom, which separates nucleic acids from impurities, and an electrophoresis buffer on top. After the target nucleic acid has been gel-purified on the upper column, a larger-diameter column with a layer of high-salt gel overlaid with electrophoresis buffer is inserted from below. The purified nucleic acid is then electroeluted into the buffer-filled gap between the separating gel and the high-salt gel, where excess counterions from the high-salt gel slow its migration and cause it to accumulate. The proposed vertical purification system outperforms the previously described horizontal system in terms of ease of use, speed, scalability, and compatibility with high-throughput workflows. Furthermore, the vertical system allows for the sequential purification of several nucleic acid species from the same sample using interchangeable salt-gel columns.

Analytical Solutions for a Fully Coupled Hydraulic‐Mechanical‐Chemical Model With Nonlinear Adsorption

ABSTRACTAdsorption characteristics play a crucial role in solute transport processes, serving as a fundamental factor for evaluating the performance of clay liners. Nonlinear adsorption isotherms are commonly found with metal ions and organic compounds, which introduce challenges in obtaining analytical solutions for solute transport models. In this study, analytical solutions are proposed for a fully coupled hydraulic‐mechanical‐chemical (HMC) model that accounts for both the Freundlich and Langmuir isotherms. To mitigate the difficulties arising from the variable coefficients, the system of second‐order partial differential equations involving three variables is linearized. The method of separation of variables, theory of integration, and Fourier series are utilized to derive analytical solutions. The analytical method presented can potentially be extended to a broad spectrum of nonlinear adsorption isotherms. The results reveal a 56.5% reduction in solute breakthrough time under the Freundlich isotherm and a remarkable 2.6‐fold extension under the Langmuir isotherm when compared to the linear isotherm. The adsorption constants of the Freundlich and Langmuir isotherms exhibit a positive correlation with breakthrough time, while the exponent of the Freundlich isotherm and the maximal adsorption capacity in the Langmuir isotherm demonstrate a negative association with breakthrough time. This study enhances the precision of solute transport prediction and provides a more scientific assessment of clay liner performance.

Optical and Catalytic Properties of Nanozymes for Colorimetric Biosensors: Advantages, Limitations, and Perspectives

AbstractDetection of colorimetric signals is commonly used in various analytical methods and for testing in non‐laboratory and resource‐limited settings. The performance of colorimetric assays is largely based on nanoparticles and their unique optical properties. Multifunctional nanoparticles combining optical and enzyme‐like catalytic properties—known as nanozymes—hold great promise for analytical applications as signal‐generating labels. However, the extensive focus on the catalytic properties leaves their unique optical properties overlooked. In this article, the use of the optical and catalytic properties of nanozymes is reviewed for analytical applications relying on the inherent optical properties of nanozymes, the colorimetric detection of a catalytically‐formed product, and colorimetric changes of nanoparticles caused by the catalytically‐formed product. The impact of the extinction coefficient of nanozymes and reaction products, as well as the kinetic parameters of nanozymes on the sensitivity and limit of detection of assays, are quantitatively evaluated. Finally, the existing limitations and prospects of nanozymes for colorimetric biosensors are summarized.

Multivariate HPLC system assessment and optimization for traditional Chinese medicine: a case study of Gastrodia elata.

The development of HPLC analytical methods for traditional Chinese medicine is intricate and time-consuming, influenced by factors such as column wear, solvent purity, and instrumental settings. A comprehensive evaluation of the HPLC system is crucial to mitigate potential variability and ensure the reliability of data. This is especially important given the complex and synergistic nature of the chemical components in traditional Chinese medicine, necessitating a multivariate measurement system analysis (MSA) to assess multiple correlated quality characteristics effectively. This study introduced a multivariate MSA method based on weighted principal components (WPC) to evaluate the HPLC system for the determination of metabolites in Gastrodia elata. By integrating multiple principal components and assigning weights according to their eigenvalues, the WPC method significantly enhanced both accuracy and robustness. It demonstrated a repeatability and reproducibility (% R&R) of 26.43% and a number of distinct categories (ndc) index of 5, confirming the system's acceptability. A full factorial experimental design was employed to identify key performance factors, leading to the recommendation to use five reference solutions for the standard curve and to triple sample preparations for improved precision and accuracy. Monte Carlo simulations confirmed the reliability of the system, showing % R&R and ndc values that follow a normal distribution, ranging from 19% to 22% and 6.07 to 7.38, respectively. Chromatographic conditions were optimized using a Box-Behnken experimental design. Subsequent validation experiments verified the method's high accuracy and reliability, with all relative standard deviation values for analytical precision, repeatability, and stability below 5%. The method also exhibited high recovery rates, exceeding 91% across three concentration levels, with RSD values under 4%. In conclusion, the application of a WPC-based multivariate MSA enabled a detailed evaluation of the HPLC system, ensuring accurate and reliable measurement of quality attributes. This method exemplified a scientifically rigorous approach for developing analytical methods in traditional Chinese medicine, enhancing both precision and reliability.

Postmortem distribution of ropivacaine and its metabolite in human body fluids and solid tissues by GC-MS/MS using standard addition method.

An analytical method was developed for determining ropivacaine and its main metabolite, 3-hydroxyropivacaine in biomedical samples using gas chromatography-tandem mass spectrometry (GC-MS/MS). Then, this established method was applied to investigate the distribution of ropivacaine and its metabolite in human fluids and solid tissues obtained from an authentic case ropivacaine involved. The fluid sample was added acetonitrile, and solid tissue was homogenized using a freezer mill and then added into acetonitrile. Then, an internal standard solution was added to the mixtures. The mixture was centrifuged at 12,000 × g for 5min, and the upper layer of acetonitrile was transferred to magnesium sulfate and octadecyl silica (C18) gel for cleaning up the sample. After centrifugation, the upper layer was then evaporated to dryness with nitrogen, and dissolved with methanol, then injected into the GC-MS/MS system. The coefficients of determination (r2) of constructed calibration curves were all greater than 0.999. The limits of detection for ropivacaine and 3-hydroxyropivacaine in target samples were 15ng/mL and 10ng/mL, respectively. The recovery rates of ropivacaine and 3-hydroxyropivacaine ranged from 97.6% to 103% and from 96.5% to 104%, respectively. The inter-day precision values of ropivacaine and 3-hydroxyropivacaine were not greater than 6.25% and 7.98%, respectively, and the inter-day trueness values were not greater than 6.90% and 8.33%, respectively; the intra-day precision and trueness values of ropivacaine and 3-hydroxyropivacaine were not greater than 3.20%, 6.78%, 7.84% and 8.99%, respectively. GC-MS/MS method for simultaneous detection and quantification of ropivacaine and 3-hydroxyropivacaine in biological samples was successfully developed. The method could also be applied to samples obtained from an authentic case; their distribution among tested fluids and solid tissues were also measured. This is the first report on the distribution of ropivacaine and its major metabolite 3-hydroxyropivacaine in a human case.

Quantifying Sahel Runoff Sensitivity to Climate Variability, Soil Moisture and Vegetation Changes Using Analytical Methods

AbstractWhilst substantial efforts have been deployed to understand the “Sahel hydrological paradox”, most of the studies focused on small experimental watersheds around the central and western Sahel. To our knowledge, there is no study on this issue covering all the watersheds located within the Sahelian belt. The absence of relevant studies may be attributed to a sparsity of in situ data leading to a dearth of knowledge on the Sahel hydrology. To fill this knowledge gap, the present study leverages analytical methods and freely available geospatial datasets to understand the effects of climatic factors, soil moisture and vegetation cover changes on surface runoff in 45 watersheds located within the Sahelian belt over two decades (2000–2021). Analyses show increasing trends in annual precipitation and potential evapotranspiration (PET) in more than 80% of the watersheds. Surface runoff, soil moisture (SM), and vegetation cover measured using the normalised difference vegetation index (NDVI) also show increasing trends in all the watersheds. Multivariable linear regression (MLR) analyses reveal that precipitation, PET, SM, and NDVI contribute about 62% of surface runoff variance. Further analyses using MLR, and the partial least squares regression (PLSR) show that precipitation and NDVI are the main factors influencing surface runoff in the Sahel. Elasticity coefficients reveal that a 10% increase in precipitation, SM and NDVI may lead to about 22%, 26% and 45% increase in surface runoff respectively. In contrast, a 10% increase in PET may lead to a 61% decline in surface runoff in the Sahel. This is the first hydrological study covering all the watersheds located within the Sahelian belt with results showing that surface runoff is influenced by climate, SM and NDVI to varying degrees. Given the unique hydrological characteristics of the Sahel, a better understanding of the different factors influencing surface runoff may be crucial for enhancing climate adaptation and ecological restoration efforts in the region such as the Great Green Wall Initiative.

Impact of green financial funding on improving the financial efficiency of a sample of companies listed on the Iraq stock exchange

The aim of this research is to identify the impact of green financing on financial efficiency by highlighting the importance of financing green activities in supporting the financial efficiency of banks. In this research, the authors adopted the descriptive analytical method and the statistical method, where (75) questionnaires were distributed to a research sample consisting of three banks: Al-Ahli Bank of Iraq, Middle East Bank, and North Bank. The questionnaires were transcribed and analyzed using Microsoft Excel. The research concluded that green financing contributes to financing sustainable activities and protecting the environment. The research also found that the interest in green financing enhances the efficiency of bank management in facing risks, while green financing has a weak impact on the performance and financial efficiency of banks. The research recommends that banks focus on sustainability and renewable energy sectors, increase investors' and customers' awareness of green activities, and emphasize the importance of green financing in achieving sustainable development.

Advances in food fortification: Ensuring a healthier humanity, types, and analytical methods

Food fortification is the practice of improving food products' nutritional value by adding necessary vitamins and minerals. This practice is typically implemented to address widespread deficiencies of these nutrients in the population and improve public health. Fortification can be achieved through various methods, including adding specific micronutrients to staple foods such as flour, oil, or salt, as well as through the addition of micronutrients to processed or packaged foods. The benefits of food fortification include reduced rates of malnutrition and related health problems, improved overall health and cognitive development, and increased productivity. Despite these benefits, there are also potential challenges to the implementation of food fortification programs, including the need for accurate monitoring and assessment to ensure the appropriate use of fortificants and to prevent over-fortification. Despite these challenges, food fortification remains a promising strategy for improving public health and reducing the burden of micronutrient deficiencies globally.

DESIGN AND SIMULATION OF S-BAND MICROWAVE AMPLIFIER FOR SATELLITE COMMUNICATIONS SYSTEM

This paper presents a novel design of S-band monolithic microwave integrated circuit (MMIC) amplifiers based on GaAs MESFET HFET-1102 transistors used in radiofrequency (RF) and microwave communications systems. Based on the Chebyshev gain response, an analytical method is used to design a two-stage lumped microwave amplifier. The matching networks constituted by lumped elements are transformed into T inductive networks, and the resulting amplifier is optimized using RF simulator software. In the following step, the lumped optimized amplifier is transformed into a distributed amplifier and implemented on Rogers TMM3 substrate largely used in microwave circuits. The final MMIC amplifier is stable in the frequency band (2-4 GHz), and excellent performances are obtained in terms of very high gain, reaching a peak of 35 dB, low input (S11) and output reflection (S22) coefficients, and very good output/input isolation (S12). For its RF characteristics, the proposed MMIC amplifier presented in this work is very suitable for space telecommunications in low earth orbit (LEO) satellites onboard receivers.

The Integration of Vietnamese Literature with French Literature in the Early 20th century: The Case of Writer Hồ Biểu Chánh

To demonstrate some manifestations of the integration of Vietnamese literature (in the case of Hồ Biểu Chánh), specifically with French literature, this paper will highlight the intersection of global and national characteristics in Vietnamese literature at that time, particularly in Hồ Biểu Chánh's adaptation of French literary works. Additionally, the paper employs analytical and synthetic methods to break down the research problems, thereby providing a clearer understanding of Hồ Biểu Chánh's unique features. This approach emphasizes the inheritance, development, and originality in certain aspects of Hồ Biểu Chánh's integration with world literature in the early 20th century.

Rapid Analytical Method for Quantification of Gamma-Hydroxybutyrate (GHB) in Hair by UPLC-MS/MS.

Gamma-hydroxybutyrate (GHB), an endogenous compound related to the neurotransmitter gamma-aminobutyric acid (GABA), is used as a therapeutic and recreational drug and as a "weapon" in drug-facilitated crimes. The very short window of detection of GHB in conventional matrices (blood and urine) makes necessary the use of alternative matrices like hair. Hair has a long window of detection and the possibility to perform segmental analysis, which makes it very useful for proving GHB intake. In the present work, a method for quantification of GHB in hair was developed and validated. Hair (10 mg) was washed twice with dichloromethane and then incubated at room temperature with Milli-Q water in an ultrasound bath for 30 min. Analysis was performed by UPLC-MS/MS using a CORTECS UPLC HILIC (1.6 μm), 2.1 × 100-mm column, and a gradient with acetonitrile and ammonium acetate (10 mM) at pH 6.0, with a total run-time of 10 min. For detection, a triple quadrupole mass spectrometer in ESI negative mode was used. The method was validated, following the criteria established in the "AAFS Standard Practices for Method Validation in Forensic Toxicology" guideline, obtaining satisfactory results for linearity (0.5-50 ng/mg), accuracy (95.0%-103.2%), imprecision (< 10.2%), limit of detection (0.1 ng/mg) and quantification (0.5 ng/mg), exogenous selectivity (no interferences), matrix effect (less than -44.2%), extraction efficiency (> 86.4%), process efficiency (> 46.1%), and autosampler stability (< 4.3%). The method was used for the analysis of 26 authentic hair samples, 25 from non-drug users, obtaining values between < LOQ and 6.25 ng/mg of endogenous GHB and 1 from a former GHB chronic user to prove abstinence.