High-performance Liquid Chromatography System Research Articles

Construction of continuous flow catalytic reactor-HPLC system with ultrahigh catalytic activity using 2D nanoflower MOF-derived Cu2O/Cu/PDA/CF catalyst

Currently, metal-organic frameworks (MOFs) derived materials have been widely concerned for the reduction of 4-nitrophenol (4-NP). However, complex recovery of powder catalysts and low utilization ratio of active sites make their application challenging. Herein, a novel Cu2O/Cu/PDA/CF catalyst has been developed for the rapid reduction of 4-NP to 4-aminophenol (4-AP). The catalyst was constructed by compositing a two-dimensional nanoflower MOF-derived nanoporous Cu2O/Cu network on a polydopamine (PDA)-modified porous copper foam by a mild and controllable in-situ reduction synthesis. Notably, an enhanced catalytic performance of Cu2O/Cu/PDA/CF was obtained for 4-NP reduction with a rate constant (k) of 0.8001 min−1, outperforming Cu/PDA/CF-X (X = 400, 500 and 600 ℃ pyrolysis temperature) catalysts (2.3–6.4 folds), and even many reported catalysts (2.3–46.5 folds). The ultrafast degradation of 4-NP was completed in 70 s. Moreover, an ingenious online continuous flow catalytic reactor (CFCR)-high performance liquid chromatography (HPLC) system was constructed for automatic and real-time monitoring of the reduction reaction. System stability experiments over 300 min revealed a surprisingly high reaction k value of 76.68 min−1 at low NaBH4 usage, significant increasing by 2–3 orders of magnitude compared with Cu2O/Cu/PDA/CF batch catalysis, due to the high aspect ratio of 2D nanoflower MOF and convection-accelerated mass transfer. This work offers new insights for the rational design of catalytic reactor and its potential application in wastewater treatment.

Metal-organic framework functionalized with deep eutectic solvent for solid-phase extraction of Rhodamine 6G in water and cosmetic products.

An NH2 -MIL-53(Al)-DES(ChCl-Urea) nanocomposite was synthesized for extraction and determination of Rhodamine (Rh) 6G from environmental and cosmetic samples. The deep eutectic solvent (DES) was prepared by mixing choline chloride and urea in a mole ratio of 1:2. NH2 -MIL-53(Al)-DES(ChCl-Urea) nanocomposite was synthesized using the impregnation method at a ratio of 60:40 (w/w). The optimum conditions were determined after NH2 -MIL-53(Al)-DES(ChCl-Urea) characterization was performed. The optimum conditions were determined as pH 8, adsorbent amount of 15mg, total adsorption-desorption time of 6min, and enrichment factor of 20. The recovery values of the solid-phase extraction method for water and cosmetic samples under optimum conditions were between 95% and 106%. NH2 -MIL-53(Al)-DES(ChCl-Urea) nanocomposite was an economically advantageous adsorbent because of its reusability of 15 times. All analyses were performed using the ultraviolet-visible spectrophotometer. The linear range, limit of detection, and limit of quantification of the method were 100-1000, 9.80, and 32.68μg/L, respectively. The obtained results showed that the synthesized nanocomposite is a suitable adsorbent for the determination of Rh 6G in water and cosmetic samples. The real sample applications were verified with the high-performance liquid chromatography system.

Insecticidal and residual effect of chlorfenapyr on different surfaces for the control of Sitophilusoryzae

The immediate and residual insecticidal effects of chlorfenapyr applied on concrete and metal surfaces were evaluated against Sitophilus oryzae adults in laboratory bioassays. The dose used was 0.016 mg active ingredient (a.i.)/cm2 which refers to the highest label dose in case of severe infestation. Treated surfaces were either kept in continuous darkness or exposed to light. A series of subsequent bioassays were conducted in the treated surfaces, starting from the day of application and continued for three consecutive months, with new insects each time. For each bioassay, mortality levels were recorded after exposure for 3, 7 and 14 days. At the same time, the dissipation of chlorfenapyr residues on the treated surfaces was estimated at different time intervals (0, 3, 7, 15, 30, 60, 90 and 120 days) after application using a high-performance liquid chromatography system with a UV-detector (HPLC-UV). According to the results, mortality rates of S. oryzae adults after direct exposure to chlorfenapyr-treated concrete surfaces were high, reaching 100% at the end of the first bioassay. However, we observed a gradual reduction in mortality with the increase of the storage (post application) interval. On the contrary, mortality on metal surfaces was high and reached in all cases 100% after 7 days of exposure, regardless of the storage interval. Regarding the residues of chlorfenapyr on the surfaces, they remained relatively constant on metal surfaces for the entire 120-day period in both illuminated and non-illuminated surfaces. On concrete, an initial 20–35% reduction was observed over the first 3 days, whereas chlorfenapyr residues remained constant for the rest of the period regardless of the presence of illumination. Our results indicate that chlorfenapyr is effective for the control of S. oryzae, but its residual efficacy is moderated by the time after application, the surface type and partially by the presence of illumination.

Quantification of orally administered chondroitin sulfate oligosaccharides in human plasma and urine.

Chondroitin sulfate (CS) has been widely administered orally to improve knee osteoarthritis (OA). CS also has various biological properties, such as anti-inflammatory, immunomodulatory, anti-oxidative, and anti-tumour activity. However, CS absorption in the digestive system and bioavailability remain controversial owing to its large molecular weight (MW). In this study, we aimed to evaluate the absorption of CS oligosaccharides (CSOS), depolymerized CS with low MW, in oral administration to humans. Four types of CS with varying MW [CS tetrasaccharide (MW. 980), CSOS-1 (MW. 1500), CSOS-2 (MW. 2800), and HMWCS (MW. 70,000)] were orally administered and quantified in plasma and urine. Exogenous CS (Exo-CS) in these samples was quantified using a high-performance liquid chromatography system equipped with a fluorescence detector. Quantitative changes of administered CS tetrasaccharide showed similar patterns in plasma and urine, therefore it was presumed that the amount of Exo-CS excreted in urine reflects its quantitative profile in blood. Considering urinary Exo-CS as a parameter of intestinal CS absorption, urinary contents of orally administered CS with varying MW were compared. Consequently, the amount of urinary Exo-CS in 24hours after administration was higher in the CSOS group than that in the HMWCS group. Additionally, in the MW distribution, urinary Exo-CS after CSOS administration showed a lower content of CSOS with a higher MW than that observed before administration. In summary, our results demonstrated for the first time that lower MW of CS is more efficiently absorbed through the digestive tract in human, and the improvement of its bioavailability is expected.

Identification and Quantification of the Component Composition of the Active Substance Gentamicin Sulfate by <sup>1</sup>Н and <sup>13</sup>С NMR Spectroscopy

Gentamicin sulfate is a broad-spectrum bactericidal aminoglycoside antibiotic produced by Micromonospora purpurea and used in clinical practice as an active substance containing a mixture of gentamicins C1 and C2. Gentamicin content is a standardised parameter controlled as part of a pharmaceutical product review. Currently, the quality control of the active substance gentamicin sulfate involves the use of high-performance liquid chromatography (HPLC) for the indirect identification of the component composition by comparison with a reference standard and for its quantification by calibration against the reference standard.The aim of the study was to develop a procedure for identifying and quantifying the components of the active substance gentamicin sulfate using nuclear magnetic resonance (NMR) spectroscopy that would not require reference standards.Materials and methods. The authors studied a sample of the active substance gentamicin sulfate using an Agilent DD2 NMR spectrometer operating at 600 MHz to record NMR spectra and an Agilent 1200 HPLC system equipped with a multiple wavelength detector (MWD) to obtain chromatograms.Results. Having determined the spectral properties of the C1, C1A, C2, C2A and C2B gentamicins comprising the active substance, the authors observed characteristic signals of the same type that corresponded to each of the gentamicins and did not overlap with other signals in the 1H and 13C spectra. These characteristic signals provided spectral markers indicative of the gentamicins of interest in the sample, with normalised integrated intensities equal to the mole fractions of the analytes. The authors compared NMR and HPLC measurements of the active substance composition.Conclusions. The authors developed a procedure for identifying and quantifying the constituents of the active substance gentamicin sulfate by 1H and 13C NMR spectroscopy, which requires less effort than HPLC procedures and no reference standards for the intended applications.

The profile of key gut microbiota members and short-chain fatty acids in patients with sepsis

Sepsis is a complex clinical disorder with heterogeneous etiological factors. Given its high mortality rate, it is considered a global health issue. Recently, the link between gut microbiota and their metabolites, especially short-chain fatty acids, in the pathophysiology of sepsis has been reported. However, there are few findings to confirm this relationship. This study aimed to evaluate some key gut microbiota members, pathogenic bacteria, and short-chain fatty acids in non-ICU patients with sepsis caused by bacteremia compared to a control group. In this case-control study, 45 stool samples from patients with sepsis and 15 healthy persons were collected from October 2021 to August 2022 in Tabriz, Iran. The position of some gut microbiota members and the main short-chain fatty acids concentration were assessed in the two groups by the Q-PCR and the high-performance liquid chromatography system. Faecalibacterium prausnitzii and Bifidobacterium sp. As bacterial with protective features in non-ICU patients with sepsis decreased significantly. Moreover, the concentrations of acetic acid and propionic acid significantly decreased in this group compared to the healthy volunteers. In contrast, the pathogenic bacteria members such as Enterobacteriaceae and Bacteroides sp. Increased significantly in the patients compared to the healthy individuals. The concentration of butyric acid decreased in the patients, but this change was not significant in the two groups. Protective and immune functions of F. prausnitzii and Bifidobacterium sp., as well as acetate and propionate, are evident. In this investigation, this profile was significantly reduced in non-ICU patients with sepsis compared to the control group.

Ultrasensitive and highly selective determination of iodate by reversed-phase ion pair HPLC–amperometric detector after online electrochemical reduction to iodide

We developed an ultrasensitive and highly selective method to quantify iodate (IO3–) in iodized salt and biological samples. In the high-performance liquid chromatography (HPLC) system, IO3– was injected with sampler and reduced to iodide (I–) online using a Coulomb detector (CD) as a pre-column reactor, retained by C18 column with the help of ion pairs, and then determined by an amperometric detector (AD). For analysis of IO3–, several parameters and reactive conditions of Coulomb detector, including applied potential, pH value, and salt concentration, were optimized to obtain the best reduction efficiency. The optimized HPLC–CD-AD method was found to be linear over a wide range of IO3– concentration (0.05–0.25 μg/mL) with appreciable recovery rates (86.90– 94.70%) of quality controls at excellent detection limits (100 pg) and acceptable variability. The analysis of IO3– in actual samples, such as urine of volunteers, iodized salt, and seawater, discovered that the method has high selectivity and little interference. It can be concluded that the proposed method was ultrasensitive and highly selective in the trace detection of IO3.

Composition and chronic toxicity of dry methanol-aqueous extract of wild-growing Satureja montana.

Saturejamontana is a wild growing medicinal plant, part of the Lamiaceae family. This herb is well known as a source of phenolic compounds, which can vary in a broad range depending on different factors and exert many pharmacological activities.

BIOCHEMICAL CHARACTERIZATION OF STEVIA ESSENTIAL OIL THROUGH DIFFERENT DRYING METHODS AND SOLVENTS

Essential extracts from plants have been used as a food and medicinal cure since ancient times. Some plants have a good portion of carbohydrates e.g., stevia is being used as an excellent alternative to synthetic compounds i.e., sugar. Therefore, it is important to chemically characterize these nutrients and study their various biological properties. This research aimed to extract essential oil from stevia plant by using Soxhlet apparatus and analysis of nutrients present in the oil were performed by high performance liquid chromatography system i.e., HPLC. Two extraction solvents i.e., hexane (60/40; v/v) and ethanol (70/30; v/v) were used to compare the concentration of bioactive compounds. The plant material was subjected to two drying methods i.e., air dry and oven dry. 10 major compounds were identified as a result of the chemical characterization, in which steviol bioside i.e., 317.01615 (m/z) and stevioside (803.2189 m/z) that is obtained from oven drying using ethanol as extraction solvent were slightly greater than steviol bioside i.e., 315.2183 (m/z) and stevioside i.e., 802.8531 (m/z) obtained from oven drying using hexane as extraction solvent. Likewise, plant material subjected to air dry with ethanol as extraction solvent resulted in greater yield of steviol bioside i.e., 317.0717 (m/z) and stevioside i.e., 803. 3179 (m/z) as compared to steviol bioside i.e., 315.1104 (m/z) and stevioside (802.3185 m/z) that is obtained by air dry using hexane as a solvent. While using fresh leaves the concentrations of compounds i.e., stevioside (799.2187 m/z), dulcoside A (787.3759 m/z) and steviol (639.4189 m/z) obtained by using ethanol were greater than concentration of compounds obtained by hexane. While Rebaudioside A (965.3213 m/z), Rebaudioside B (803.3717 m/z), Rebaudioside C (940.4276 m/z), Rebaudioside D (1066.4763 m/z), Rebaudioside E (964.4273 m/z) and Rebaudioside F (789.3857 m/z) obtained by using hexane as extraction solvent were greater as compared to concentration of compounds obtained by using ethanol. Based on these results, we can suggest that Stevia rebaudiana Bertoni can be a natural source of antioxidant, anti-inflammation and antimicrobial properties. It can also be considerd as a potential source of essential oil. These results suggest that the leaves of S. rebaudiana Bertoni can serve as therapeutic agents or in prevention of certain inflammatory diseases through their radical-scavenging capacities.

Separation and purification of glycosides from medicinal plants based on strong polar separation medium with online closed-loop mode

Natural glycosides widely distributed in medicinal plants are valuable sources of therapeutic agents, showing various pharmacological effects. The separation and purification of natural glycosides are meaningful for their pharmacological research, which face with great challenges due to the complex of medicinal plants samples. In this work, two kinds of functional monolithic separation mediums A and S were fabricated and fully applied in the online extraction, separation and purification of active glycoside components from medicinal plants with a simple-procedure closed-loop mode. Chrysophanol glucoside and physcion glucoside were detected and separated from Rhei Radix et Rhizoma using separation medium A as a solid-phase extraction adsorbent. Rhapontin was isolated and purified from Rheum hotaoense C. Y. Cheng et Kao using separation medium S as the stationary phase of high-performance liquid chromatography. Compared to the reported literatures, high yield of 5.68, 1.20 and 4.76 mg g−1 of these three products were obtained with high purity. These two online closed-loop mode methods were carried out using high-performance liquid chromatography system, in which the sample injection, isolation and purification procedures are all online mode, and reduced loss compared to offline extraction and purification procedures, thus achieving high recovery and high purity.

Column Watch: Methods for the Passivation of HPLC Instruments and Columns

Metal-analyte interaction is a type of nonspecific adsorption (NSA) that occurs mainly between acidic analytes and active adsorptive sites present in the metal surfaces of the fluidic path of any chromatographic system. NSA represents a chromatographic challenge since it may lead to poor peak shape, low recovery, and poor performance from the high performance liquid chromatography (HPLC) system. As a result, many solutions that circumvent and mitigate this type of secondary interaction have been published or commercialized in the last few years. Such solutions encompass swapping stainless steel components for non-reactive polymers, “biocompatible” metals or alloys, the addition of additives into the mobile phase, pretreating the system with large amounts of sample or strong acids, and the use of coated stainless steel materials. This article explores these solutions in more detail, particularly the recent adaptation and benefits of coated metal surfaces in LC.

Evaluation of volatile and thermal properties of boza, a traditional fermented beverage

Although boza is widely preferred and consumed, there is no detailed study on volatile and thermal characteristics. A liquid–liquidextraction (LLE) method has been proposed for the volatile extraction of boza using GC-MS. DB-Wax column from 50 °C to 250 °C at a rate of 4 °C/min with a final hold at 250 °C for 10 min. A helium gas was selected as a carrier gas with a 3.2 ml/min linear velocity. The retention time of the internal standard (4-nonanol) used in our study, was detected in the middle of the chromatogram, and the peak response was relatively stable. The odor activity values (OAVs) were utilized to elucidate the aroma and key odorant substances. Based on OAVs, the most important aroma compounds identified in boza were hexanoic acid [25.1, cheesy goat], 4-vinyl phenol [12.1, phenolic/burnt], acetoin [9.1, buttery/creamy], acetic acid [6.7, vinegary/irritant] and octan-2-ol [3.5, coconut]. The high-performance liquid chromatography (HPLC) system was used to determine the organic acids in boza. The quality parameters of the method were established in terms of the linearity of the calibration, the limit of quantification, the limit of detection, and recovery experiments. The proposed method showed a good recovery from 79.47 to 109.96%. The proposed method was found to be specific as no interference peaks were observed for blank samples. Regarding thermal properties, onset temperature (To), peak temperature (Tp), and end set temperature (Te) increase with the heating rate. In contrast, with increasing temperature, there was a slight decrease in the endothermic peak width (EPW) and peak height index (PHI) values. The level of alcohol was 0.06% below the criteria of the Turkish Boza Standard (TSE 9778).

LC-MS Method Development and Optimization for Small Drug Analysis in Urine

Both amphetamine and methamphetamine are considered to be illegal chemicals, and hence, the purchase, possession, and use of these drugs is forbidden in many nations. Within the fields of forensic and clinical toxicology, there has been a recent uptick in the detection and quantification of illicit substances within urine samples. Objective: To detect and quantify both drugs in urine samples utilizing caffeine as an internal standard with an optimized liquid-liquid extraction procedure. Methods: An alternative rapid and efficient method of liquid chromatography – electron spray ionization – Tandem mass spectrometry (LC – ESI – TMS) was developed and optimized. The chromatographic separation was carried out using an isocratic high-performance liquid chromatography (HPLC) system, and the eluent that was applied was a mixture of 20% acetonitrile and 80% buffer with a pH of 2.6 that included 10mM ammonium acetate and 0.1% trifluoroacetic acid. The run duration was 9 minutes, and the detection was accomplished at 210 nm with a flow rate of 1 mL/min utilizing triple quadruple MSMS to validate ionic transitions following direct infusion and fragmentation of analytes. Results: An excellent linearity was seen in the calibration curves of amphetamine and methamphetamine in urine samples across the concentration range of 0-10 mg/L, with a regression coefficient of 0.91 and 0.97, respectively, for each of these substances. Conclusions: More compounds are able to be identified in urine as chromatographic techniques, such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS), continue to improve in terms of their sensitivity

Nanoscale Pluronic® micellar templates with varying %EO content for controlled drug release and cytotoxicity

This study investigates the self-assembly in ethylene oxide (EO)-propylene oxide (PO)-based block copolymers (BCPs) with various molecular features like molecular weight, EO/PO ratio, HLB (Hydrophobic lipophilic balance) in aqueous solution environment. Our BCP solution systems exhibit significant changes in solution behaviour that showed micellization, micelle growth/ transition, and progressively phase separation (2ϕ), all of which are well explained by clear solution, blue point (BP) and cloud Point (CP) respectively. The solubilization of the highly hydrophobic anticancer drug-Quercetin (QCT) in such BCPs is examined using UV–Visible spectroscopy. The spectral findings inferred the dissolution capability of QCT in the examined copolymeric micellar systems in terms of drug loading efficiency (DL%), encapsulation efficiency (EE%), partition coefficient (P), and standard free energy of solubilization (ΔGo). Amongst the varied tested BCPs, it was observed that Pluronics® P123 and F127 exhibited an enhanced QCT solubilization capability than others and is explained in terms of hydrophobicity and hydrophilicity. The micellar size distribution profile expressed as hydrodynamic diameter (Dh) was determined for QCT-loaded and QCT-unloaded BCP micelles employing dynamic light scattering (DLS). The drug release profile was fitted employing various kinetic models, allowing this study to serve as an excellent foundation for QCT delivery. Reversed-phase High-performance liquid chromatography (HPLC) system determined the retention period in the QCT-loaded micelle while the structural alterations involved in Pluronics®-QCT system is inferred using small-angle neutron scattering (SANS). Fourier transform infrared spectroscopy (FT-IR) depicted the compatibility between Pluronics® and QCT which was validated further from the evaluated optimum descriptors using Gaussian 09 computational simulation framework. It was discovered that the QCT-loaded micelles exhibited a greater anticancer effect than free drug when tested in vivo on cancer cells. The anticancer activity of QCT-loaded F127 micelles was determined to be the strongest. Thus, the current study on QCT solubilization in Pluronics® will benefit considerably from its investigated outcomes.

A simple and accurate LC‑MS/MS method for monitoring cyclosporinA that is suitable for high throughput analysis.

With time, the number of samples in clinical laboratories from therapeutic drug monitoring has increased. Existing analytical methods for blood cyclosporin A (CSA) monitoring, such as high-performance liquid chromatography (HPLC) and immunoassays, have limitations including cross-reactivity, time consumption, and the complicated procedures involved. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has long been considered the reference standard owing to its high accuracy, specificity, and sensitivity. However, large numbers of blood samples, multi-step preparation procedures, and longer analytical times (2.5-20 min) are required as a consequence of the different technical strategies, to ensure good analytical performance and routine quality assurance. A stable, reliable, and high throughput detection method will save personnel time and reduce laboratory costs. Therefore, a high throughput and simple LC-MS/MS method was developed and validated for the detection of whole-blood CSA with CSA-d12 as the internal standard in the present study. Whole blood samples were prepared through a modified one-step protein precipitation method. A C18 column (50x2.1 mm, 2.7 µm) with a mobile phase flow rate of 0.5 ml/min was used for chromatographic separation with a total running time of 4.3 min to avoid the matrix effect. To protect the mass spectrometer, only part of the sample after LC separation was allowed to enter the mass spectrum, using two HPLC systems coupled to one mass spectrometry. In this way, throughput was improved with detection of two samples possible within 4.3 min using a shorter analytical time for each sample of 2.15 min. This modified LC-MS/MS method showed excellent analytical performance and demonstrated less matrix effect and a wide linear range. The design of multi-LC systems coupled with one mass spectrometry may play a notable role in the improvement of daily detection throughput, speeding up LC-MS/MS, and allowing it to be an integral part of continuous diagnostics in the near future.

Development of a HPLC system using a phase-separation multiphase flow as an eluent coupled to a silica-particle packed column.

The study reports the development of a high-performance liquid chromatography (HPLC) system in which a phase-separation multiphase flow as the eluent and a silica-particle based packed column as the separation column were combined to form the phase separation mode. Twenty-four types of mixed solutions of water/acetonitrile/ethyl acetate and water/acetonitrile were applied as eluents to the system at 20°C. 2,6-Naphthalenedisulfonic acid (NDS) and 1-naphthol (NA) were injected as model analytes into the system. They showed separation tendency in organic solvent-rich eluents in normal-phase mode and NA was detected earlier than NDS. Subsequently, seven types of the ternary mixed solutions were examined as eluents in the HPLC system at 20°C and 0°C. These mixed solutions worked as a two-phase separation mixed solution, providing a phase-separation multiphase flow at 0°C in the separation column. In the organic solvent-rich eluent, the mixture of analytes was separated at both 20°C (normal-phase mode) and 0°C (phase-separation mode), with NA being detected earlier than NDS. The separation at 0°C was more efficient than at 20°C. In the water-rich eluent, the mixture of NDS and NA was not separated at 20°C but was separated at 0°C (phase-separation mode), with NDS being detected earlier than NA. We also discussed the separation mechanism of phase-separation mode in HPLC together with the computer simulation for the multiphase flow in the cylindrical tube having sub-μm inner diameter.

Changing on the Concentrations of Neonicotinoids in Rice and Drinking Water through Heat Treatment Process.

Neonicotinoids (NEOs) have become the most widely used insecticides in the world since the mid-1990s. According to Chinese dietary habits, rice and water are usually heated before being consumed, but the information about the alteration through the heat treatment process is very limited. In this study, NEOs in rice samples were extracted by acetonitrile (ACN) and in tap water, samples were extracted through an HLB cartridge, then, a high-performance liquid chromatography system and a triple quadrupole mass spectrometry (HPLC-MS/MS) were applied for target chemical analysis. The parents of NEOs (p-NEOs) accounted for >99% of the total NEOs mass (∑NEOs) in both uncooked (median: 66.8 ng/g) and cooked (median: 41.4 ng/g) rice samples from Guangdong Province, China, while the metabolites of NEOs (m-NEOs) involved in this study accounted for less than 1%. We aimed to reveal the concentration changes of NEOs through heat treatment process, thus, several groups of rice and water samples from Guangdong were cooked and boiled, respectively. Significant (p < 0.05) reductions in acetamiprid, imidacloprid (IMI), thiacloprid, and thiamethoxam (THM) have been observed after the heat treatment of the rice samples. In water samples, the concentrations of THM and dinotefuran decreased significantly (p < 0.05) after the heat treatment. These results indicate the degradation of p-NEOs and m-NEOs during the heat treatment process. However, the concentrations of IMI increased significantly in tap water samples (p < 0.05) after heat treatment process, which might be caused by the potential IMI precursors in those industrial pesticide products. The concentrations of NEOs in rice and water can be shifted by the heat treatment process, so this process should be considered in relevant human exposure studies.

Evaluation of Heterogeneous Catalytic Ozonation Process for the Removal of Micropollutants from Water/Wastewater: Application of a Novel Pilot-Scale Continuous Flow System

The present study evaluates the removal of micropollutants from water/wastewater contaminated sources through the application of a heterogeneous catalytic ozonation process, using a pilot-scale continuous operation unit, composed of a membrane module for the diffusion and effective dilution of ozone into the liquid phase to be treated and a plug flow reactor/continuous stirred tank reactor (PFR/CSTR) contact reactor system in series, where the catalyst is recirculated in dispersion mode. The solid materials tested as catalysts are natural and calcined zeolite, Bayoxide and alumina, whereas the examined micropollutants, used in this case as probe compounds, are p-chlorobenzoic acid (p-CBA), atrazine, benzotriazole and carbamazepine. A high-performance liquid chromatography system was used to determine the removal of micropollutants. In the case of p-CBA, an ozone-resistant compound, the addition of catalyst was found to significantly enhance its degradation rate, leading to &gt;99% removal under the optimum defined conditions, i.e., in terms of catalyst concentration, pH, temperature, and process time. On the other hand, in the case of atrazine, a different ozone-resistant compound, the introduction of examined catalysts in the ozonation process was found to reduce the degradation of micropollutant, when compared with the application of single ozonation, indicating the importance of specific affinity between the pollutant and the solid material used as catalyst. Benzotriazole, a moderately ozone-reactive compound was degraded by more than 95% under all experimental conditions and catalysts tested in the pilot unit, while carbamazepine, a highly ozone-reactive compound, was completely removed even during the first stage of treatment process (i.e., at the membrane contactor). When increasing the pH value (in the range 6–8) and the contact time, the performance of catalytic ozonation process also improved.

A simple ion chromatography-mass spectrometry method for amino acid analysis in beer.

The amino acid footprint of different beer samples was analyzed using ion chromatography coupled with electrospray ionization mass spectrometry. A tailor-made polymer-based cation-exchange resin was operated with a mass spectrometry-compatible eluent under isocratic conditions on a standard high-performance liquid chromatography system coupled to a single quadrupole mass spectrometer using formic acid as a volatile eluent ion source. The partially separated peaks of the isomeric pair isoleucine/leucine were processed according to their area response ratio using vertical peak splitting or Gaussian fit. Additionally, the chromatographic resolution of the isomers was optimized with an adjusted, solely aqueous mobile phase from 0.85 to 2.92. Ion suppression in the electrospray ion source was investigated for the derivatization-free method and found to be insignificant (recovery value 100±15%) for 15 out of the 20 analytes. Quantitative results for various beer and mixed-beer beverages were found to be in high agreement with existing methods. Simultaneous photometric detection demonstrated the method's ability to successfully remove most of the interfering matrix compounds.

Development of a HPLC fluorometric method for the quantification of enfuvirtide following in vitro releasing studies on thermosensitive in situ forming gel

Due to the presence of peptidase and protease in the gastrointestinal tract, peptides are subjected to digestion and inactivation when administrated orally. To avoid degradation and maintain the desired efficacy of peptide drugs, there is a demand to develop transdermal and intradermal delivery systems. This requires efficient and specific analytical methods to separate and quantify the peptide drugs from the formulation and the skin matrix in the early stages of pharmaceutical development. A high-performance liquid chromatography (HPLC) system equipped with a fluorometric detector was used to quantify enfuvirtide, which is the first fusion inhibitor for HIV treatment. The HPLC method was developed and validated according to the ICH Q2(R1) guidelines. The viability of the method was demonstrated during in vitro studies, where samples were analysed following intradermal administration of a thermosensitive in situ forming gel. Compared with previously reported methods, this assay proved efficient, sensitive and accurate, with a detection limit of 0.74 μg/mL and a run time of 9 min, mitigating the use of any internal standards and detergents. The addition of an organic solvent to the samples successfully solved the problem of low recovery caused by the adsorption of the drug to the plastic consumables in the sample treatment process. The amount of enfuvirtide releasing from the in situ gel through skin after 7 hours was 16.25 ± 7.08 μg, which was significantly lower than the reconstituted FUZEON® itself (26.68 ± 10.45 μg), showing a longer release profile. The results may be beneficial as a constructive input for future enfuvirtide quantification within a preclinical setting through in vitro release studies across the skin.Graphical