Chromatographic Separation Techniques Research Articles

Rapid generation of well‐defined biodegradable poly(lactide‐co‐glycolide) libraries through chromatographic separation

AbstractPoly(lactide‐co‐glycolide) (PLGA) is a biodegradable copolymer and widely used in pharmaceuticals. Commercially available PLGAs are produced through ring‐opening polymerization, which results in inevitable dispersity in molecular weight and chemical composition (i.e., lactide‐to‐glycolide ratio), influencing bulk properties such as degradation, mechanics, and morphology. In this study, an automated chromatographic separation technique was employed to generate a series of well‐defined, low‐dispersity fractionated PLGAs from a single commercially available PLGA (lactide‐to‐glycolide ratio = 50:50). The structural and compositional dependence of properties for pharmaceutical applications in the form of nanofibers and nanoparticles were systematically investigated. The properties of new PLGAs by further separation were significantly dependent on composition. The molecular weight ranges were reduced, while the morphology of nanofibers and nanoparticles became more uniform. Importantly, the stability, mechanical strength, and drug loading increased, and the period of sustained release profile also increased. In brief, our data show that the automated chromatographic separation technique allows for precise control of the molecular weight and lactide‐to‐glycolide composition ratio of PLGA, in contrast to the traditional method. The use of well‐defined and fractionated new PLGA materials holds significant promise for enhancing the potential of PLGA in future pharmaceutical applications.

Isolation, Characterization and Antibacterial Activity Study of Bioactive Compounds from Leaves of Cyphostemma cyphopetalum

Background:: Cyphostemma cyphopetalum is a herbaceous climber species within the Vitaceae family, found in various tropical and subtropical regions of Africa. It has a history of traditional use in Ethiopia for treating various health issues in humans and livestock, includ-ing snake bites, rabies, and eczema. Despite its reported ethnomedicinal uses, there is a lack of sufficient scientific literature regarding the isolation and characterization of its bioactive chem-ical compounds. Objective:: The objective of this work was to isolate bioactive compounds from the leaves of Cyphostemma cyphopetalum, characterize their chemical structures using FTIR and NMR spec-troscopy, and evaluate their antimicrobial activities. Methods:: Isolation was done using column chromatographic separation techniques. Spectro-scopic techniques, including Fourier transform infrared and nuclear magnetic resonance, were used for functional group identification and structural elucidation. Moreover, the paper disc dif-fusion bioassay method was used to evaluate the antibacterial activity of the isolated bioactive compounds. Results:: Three fractions were successfully isolated using chloroform with dichloromethane and chloroform with ethyl acetate as eluting solvents and silica gel as a stationary phase. After care-ful interpretation of the experimental results and comparison with the literature, the isolated fractions were constituted mainly by stigmasterol (fraction 1), β-sitosterol (fraction 2), and trans-resveratrol (fraction 3). The antibacterial activities of each isolated fraction were tested against Ralstonia solanacearum, a gram-negative bacterium, and Staphylococcus aureus, a gram-positive bacterial pathogen.Comparatively, the highest mean inhibitory value of 10.03 ± 0.13 mm was exhibited by fraction 2, which was followed by 6.25±0.05 mm inhibition activity recorded for fraction 1 against R. solanacearum, while fraction 3 did not exhibit any bacterial activity against both the strains. Conclusion:: We have successfully isolated and characterized three compounds (1-3) from leaves of C. cyphopetalum and evaluated their antibacterial activity. A maximum mean inhibi-tory value of 10.03 ± 0.13 mm was exhibited by compound 2 against R. solanacearum.

Two new benzoyl-sesquiterpenes from Mesona chinensis

Mesona chinensis is a common medicinal and edible plant in the Lingnan region of China, which has extensive pharmacological activity. However, the study of its chemical constituents is not sufficient. In this study, a variety of modern chromatographic separation techniques were used to isolate two compounds from 95% ethanol extract of the grass parts of M. chinensis. Their absolute configurations were determined by ultraviolet spectroscopy(UV), infrared spectroscopy(IR), high resolution mass spectrometry(HR-ESI-MS), 1D and 2D nuclear magnetic resonance(1D NMR and 2D NMR), and single-crystal X-ray diffraction(SC-XRD). Specifically, they were two new benzoyl-sesquiterpenes and named mesonanol A and mesonanol B, respectively. The results of the pharmacological activity evaluation showed that neither of the two new compounds showed obvious antiviral and anti-inflammatory activities.

Special Issue on “Applications of Chromatographic Separation Techniques in Food and Chemistry”

Chromatographic techniques and methods are experiencing significant growth in various industries [...]

Evaluation of the potential of endophytic Trichoderma sp. isolated from medicinal plant Ampelopsis japonica against MRSA and bioassay-guided separation of the anti-MRSA compound.

Endophytic fungi have been recognized as a valuable source for the production of biologically active compounds with potential applications in various domains. This study aimed to isolate endophytic fungi from Ampelopsis japonica (Thunb.) Makino and assess their anti-MRSA activity. Meanwhile, chromatographic separation techniques were applied to analyze the constituents of endophytic fungal secondary metabolites. The isolate BLR24, which exhibited strong inhibition activity against MRSA, was identified as Trichoderma virens based on morphological characteristics and ITS sequence analyses. The ethyl acetate extract of BLR24 (EA-BLR24) showed good anti-MRSA activity with the MIC and MBC values of 25 μg/mL and 50 μg/mL, separately. The inhibition of biofilm formation was up to 34.67% under MIC concentration treatment. Meanwhile, EA-BLR24 could significantly reduce the expression of biofilm-related genes (icaA, sarA, and agrA) of MRSA. Based on LC-MS/MS analysis, twenty compounds in EA-BLR24 could be annotated using the GNPS platform, mainly diketopiperazines. The anti-MRSA compound (Fr.1.1) was obtained from EA-BLR24 by bioassay-guided fractionation and determined as gliotoxin. The results indicated that endophytic Trichoderma virens BLR24 isolated from the medical plant A. japonica roots could be a promising source of natural anti-MRSA agents. Endophytic fungal secondary metabolites are abundant in biologically active compounds. Endophytic fungi from medicinal plants could be a source yielding bioactive metabolites of pharmaceutical importance.

Spectrophotometric Multi-Component Quantitation of Rosiglitazone, Glibenclamide and Metformin HCl in Pharmaceutical Dosages Form by using Cramer’s Matrix

Objective: This article illustrates the development of a simple, precise and accurate spectrophotometric analysis method for the determination of Rosiglitazone, Glibenclamide and Metformin hydrochloride in their pharmaceutical preparations by using Cramer's matrix. Method: The absorbance of the sample solution was measured at 315.6nm and 229.2nm for the estimation of rosiglitazone and glibenclamide, respectively and at 237.0nm for estimation of metformin hydrochloride by Shimadzu double beam UV-visible spectrophotometer. Results: The result of the analysis for method was tested and validated for various parameters according to ICH guidelines and found satisfactory. The method was successfully applied for the determination of these drugs in their tablet dosage forms. Conclusion: Simultaneous estimation of active ingredients in multicomponent pharmaceutical products normally requires the use of chromatographic separation techniques, like thin layer chromatography, high performance thin layer chromatography, high performance liquid chromatography or gas chromatography etc., followed by their quantitation. But this article illustrates direct spectroscopic estimation of multicomponent formulation by using Cramer's matrix.

Selective separation and determination strategy for monitoring E100, E127, E129 and E133 in foodstuffs: Vortex assisted sequential-simultaneous liquid phase micro-extraction

A green, speedy and handy, vortex assisted sequential-simultaneous liquid phase micro-extraction procedure (VA-SS-LPME) was established first time without using any instrumental chromatographic techniques for separation, preconcentration and spectrophotometric determination of four important popularly and widely used food colorants, namely curcumin (E100), erythrosine (E127), allura red (E129) and brilliant blue (E133). Here, n-nonanol and n-nonanol based deep eutectic solvent were used as extraction solvents. The procedure has included two simultaneous and sequential separation steps by different extractants and two simultaneous UV–vis spectrophotometric determination steps. First, simultaneous separation of E100 and E127 from aqueous solution containing E129 and E133 was achieved and then simultaneous separation of E129 and E133 from aqueous solutions was applied and simultaneous spectrophotometric determinations were performed finally for binary mixture dyes (E100 and E127) and (E129 and E133). The parameters including pH, types and amounts of extractants, vortex time and rate, centrifugation time and rate were investigated in detail for sequential two steps separation and quantitative simultaneous extraction of the dyes. Interference effect of matrix ions, target and other dyes were examined. Possible envisaged extraction mechanisms were elucidated. Green analytical procedure index (GAPI) and analytical eco-scale (AES) parameters of the procedure were determined. As last, E100, E127, E129 and E133 contents of some foodstuffs and pharmaceuticals such as confectioneries, beverages, drugs and syrups were determined by applying optimized procedure. Colourful food additive concentrations of real samples were determined between 2.9 and 93.8 µg/g and 5.3–112.4 µg/mL for solid and liquid samples, respectively.

Analytical approach to assess anti-nutritional factors of grains and oilseeds: A comprehensive review

This review aims to explore the various antinutritional factors found in grains and oilseeds, their sources, and the different methods employed to mitigate their effects. Both traditional and innovative processing techniques have been utilized to reduce antinutrients. Traditional methods such as dehulling, soaking, boiling, pressure cooking, sprouting, and fermentation have proven effective in reducing specific antinutrients like α-galactosides, phytic acid, enzyme inhibitors, lathyrogens, lectins, saponins, and tannins. However, optimization of these techniques is necessary to maximize their effectiveness and minimize antinutrient content. The review also provides an overview of various analytical methods used to quantify antinutritional factors in grains and oilseeds. These methods encompass classical gravimetric and titrimetric analysis, potentiometric titrations, chromatographic and electrophoretic separation techniques, as well as spectroscopic methods, fluorescence, and biosensors. A systematic and chronological review of these analytical approaches and detection systems is presented. Furthermore, the review identifies research gaps and highlights potential areas for future exploration in the field of antinutrients in grains and oilseeds. By addressing these gaps, we can further enhance our understanding and develop more effective strategies to mitigate antinutrients, thus promoting the utilization of grains and oilseeds for their optimal health benefits.

Biological production of epicoccamide-aglycone and its cytotoxicity

Epicoccamide (EPC) is an O-d-mannosylated acyltetramic acid of Epicoccum origin and is a bolaamphiphilic fungal polyketide. EPC displays weak toxicity against Staphylococcus aureus and HeLa cell lines. The EPC biosynthetic gene cluster was previously identified in Epicoccum nigrum and knockout of the glycosyltransferase gene (epcB) abolished EPC production. EPC-aglycone was expected in the epcB knockout but was not found. This study demonstrates that extractive culture using the hydrophobic resin Diaion HP-20 resulted in the production of EPC-aglycone, which was isolated using chromatographic separation techniques, and its structural identity was substantiated by chemical analyses. EPC-aglycone displayed strong antibacterial activity against Staphylococcus aureus, with the minimal inhibitory concentration of 1 μg/mL (64 μg/mL for EPC). EPC-aglycone displayed higher levels of growth inhibition against HeLa cell line (the half inhibitory concentration, 19 μM) and WI-38 (15 μM) cell line than EPC (76 μM and 38 μM vs. HeLa and WI-38, respectively). The dose–response curve fit of growth inhibition indicated that EPC-aglycone adopted a shallow curve (low slope factor), which was different from that of EPC, suggesting that their cellular targets are distinct from each other. This study substantiates that the d-mannose attachment is the final step in EPC biosynthesis, showcasing a glycosylation-mediated modulation of the biological activity of simple acyltetramic acid. This study also highlights the usefulness of extractive cultures in mining cryptic microbial natural products.

Research progress on the construction and applications of metal-organic frameworks in chromatographic stationary phases

Metal-organic frameworks (MOFs) are a class of porous crystalline materials composed of metal centers or clusters assembled with organic ligands. These materials possess excellent properties, such as large surface areas, high porosities, uniform pore sizes, and diverse structures. Thus, MOFs have been widely applied in various fields, including catalysis, adsorption, sensing, sample pretreatment, and chromatographic separation. The applications of MOFs as stationary phases for chromatographic separation and analysis have attracted considerable attention from the research community in recent years. Compared with traditional chromatographic stationary phases, such as mesoporous silica, nanoparticles, and porous layers, MOFs possess flexible and tunable pore sizes and structures, thereby enabling precise control over their intermolecular interactions. Furthermore, the wide range of functional ligands and topologies of MOFs could potentially facilitate the separation and analysis of complex samples. These unique advantages render MOFs highly suitable for constructing novel chromatographic stationary phases.This article focuses primarily on the construction methods of MOFs as chromatographic stationary phases, and provides an overview of the latest research advancements in their applications in several chromatographic separation techniques such as high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrochromatography (CEC). The existing methods for the preparation and construction of MOFs-based chromatographic stationary phases are classified and evaluated. The construction methods for MOFs as stationary phases for HPLC mainly include filling, precursor-doped polymerization, and post-modification. The construction methods for MOFs as stationary phases for GC predominantly include in situ growth, static coating, and dynamic coating. The stationary phases for CEC can be categorized into packed columns, monolithic columns, and open-tubular columns. Compared with monolithic and packed columns, open-tubular CEC (OT-CEC) offers numerous advantages, including a more flexible and convenient preparation method, enhanced compatibility with various separation media, and higher separation efficiency. Consequently, OT-CEC has emerged as an important method for investigating the preparation of stationary phases for CEC. Several methods such as physical adsorption, covalent attachment, and electrostatic interactions have been developed for the preparation and modification of MOFs-based CEC stationary phases, and extensive studies have been conducted to optimize the performance and applications of MOFs in OT-CEC. However, the existing methods for constructing MOFs-based chromatographic stationary phases present certain limitations. Therefore, the selection of the appropriate MOFs, optimization of their preparation methods, and examination of their performance in different separation modes have become the focus of intensive research.This review also summarizes the different analytical targets (e. g., chiral small molecules, biomacromolecules, and nonchiral molecules) and corresponding separation effects achieved using various MOFs-based chromatographic stationary phases. Finally, future studies focusing on the development of MOFs as chromatographic separation media are discussed. Overall, this review provides a valuable reference for the rational construction and practical applications of advanced MOFs-based chromatographic stationary phases.

Research progress on preparation and applications of covalent organic framework-based chromatographic stationary phases

Given continuous developments in industrial and scientific research, the separation and analysis of complex systems with high sensitivity, throughput, and selectivity is facing new challenges. Chromatography plays an irreplaceable role in separation science and is widely applied in environmental monitoring, pharmaceutical analysis, and food safety. Owing to their outstanding advantages, such as high loading capacity, precise quantification, and good reproducibility, chromatographic separation techniques based on various retention mechanisms have been utilized to detect different analytes. The stationary phase is the core material of chromatographic columns and has an extremely important influence on their separation performance. The selectivity and efficiency of separation largely depend on the chromatographic stationary phase. However, traditional stationary phases, such as silicon-based matrices, are characterized by complex preparation processes, poor permeability, large mass transfer resistance, and a narrow pH range. In addition, polymer matrices show poor mechanical stability and susceptibility to swelling, which limit their applications in the field of separation. Therefore, the development of novel stationary phases with the advantages of traditional stationary phases has become a research emphasis in the field of analytical science in efforts to meet separation requirements under different environments. Various stationary phases based on novel porous materials, such as metal organic frameworks (MOFs), porous organic cages (POCs), and covalent organic frameworks (COFs), are used for chromatographic separation. As mesh crystalline porous materials, MOFs have the advantages of a large surface area, adjustable structure, and easy functionalization; thus, they are widely used as chromatographic stationary phases in reverse-phase chromatography, hydrophilic-mode chromatography, mixed-mode chromatography, and other separation modes. However, because the pore size of MOFs is small and most MOFs demonstrate poor chemical stability under acidic or alkaline conditions, their applications in chromatographic separation are greatly limited. COFs are porous, crystalline polymer materials composed of light elements (H, O, C, N, B, and Si) connected via covalent bonds. Their advantages include a low density, large specific surface area, high porosity, good chemical and thermal stability, regular pores, and adjustable pore sizes. Because of their unique structures and properties, COFs are widely used in many fields such as catalysis, enrichment, gas capture, and sensing. COF materials are also suitable for separation analysis and considered ideal materials for novel chromatographic stationary phases. This review summarizes the latest research progress on the preparation and applications of COF-based chromatographic stationary phases over the past five years. First, the preparation of COF-based stationary phases (SiO2@COFs stationary phase, COFs monolithic stationary phase, pure COFs stationary phase and COFs-coated stationary phase) is introduced. The latest applications of COF-based stationary phases in the separation of organic compounds, isomers, and chiral compounds are then described in detail. Finally, the future development trends and challenges of chromatographic stationary phases based on COFs are discussed to provide new ideas for the future design and development of novel chromatographic stationary phases based on COFs.

Kinetic resolution of substituted amido[2.2]paracyclophanes via asymmetric electrophilic amination

Planar chiral [2.2]paracyclophane derivatives are a type of structurally intriguing and practically useful chiral molecules, which have found a range of important applications in the field of asymmetric catalysis and material science. However, access to enantioenriched [2.2]paracyclophanes represents a longstanding challenge in organic synthesis due to their unique structures, which are still highly dependent on the chiral chromatography separation technique and classical chemical resolution strategy to date. In this work, we report on an efficient and versatile kinetic resolution protocol for various substituted amido[2.2]paracyclophanes, including those with pseudo-geminal, pseudo-ortho, pseudo-meta and pseudo-para disubstitutions, using chiral phosphoric acid (CPA)-catalyzed asymmetric amination reaction, which was also applicable to the enantioselective desymmetrization of an achiral diamido[2.2]paracyclophane. Detailed experimental studies shed light on a new reaction mechanism for the electrophilic aromatic C-H amination, which proceeded through sequential triazane formation and N[1,5]-rearrangement. The facile large-scale kinetic resolution reaction and diverse derivatizations of both the recovered chiral starting materials and the C-H amination products showcased the potential of this method.

Copper sulphate immobilized on P(AN-NIPAM-MBAM) terpolymer as a highly efficient catalyst for the selective reduction of nitro-arenes

A new copper sulphate anchored to an acrylonitrile-N-isopropylacrylamide-bisacrylamide based P(AN-NIPAM-MBAM) terpolymer support has been employed as a catalyst for the hydrogenation of varied substituted nitro-arenes affording corresponding amines with excellent yield. Application of hydrogen source from NaBH4 in combination with NaOH under water and/or methanol solvent system at 50-55°C has been investigated. The terpolymer and catalyst have been characterized by ICP-OES, FT-IR, TGA, SEM and EDAX analysis methods. Different parameters supporting chemo-selective hydrogenation such as concentration of NaBH4, TP-CuSO4, assisting base and solvents have been investigated. Controllable vigorous H2 gas evolution, low-temperature requirement, feasibility under air atmosphere, low catalyst loading, use of non-toxic reagents and solvents, high isolated yield, easy work-up procedure, purification without involving tedious column or flash chromatographic separation techniques, makes this protocol highly significant from the implementation point of view.

Applications of deep eutectic solvents in microextraction and chromatographic separation techniques: Latest developments, challenges, and prospects

Deep eutectic solvents (DESs) have recently sparked considerable attention in a variety of scientific and technological fields. The unique properties of DESs include biodegradability, easy preparation, low cost, and tuneability, rendering them a new and prospective alternative to hazardous solvents. Analytical chemistry is one of the most appealing fields where DESs proved to be applicable in either sample preparation or chromatographic separation. This review summarizes the new horizons dedicated to the application of DESs in microextraction and chromatographic separation. The utilization of DESs in microextraction, in chromatography as mobile phase additives, and in chromatographic material preparation processes is outlined. The enhancements in chromatographic performance achieved using DESs and any potential explanations deduced from the experimental findings were primarily discussed. An additional brief discussion on DESs preparation, characterization, and properties is addressed in this work. Finally, current challenges and future trends are also presented, supplying evidence for distinct possibilities regarding new research approaches involving DESs. This review can represent a guide and stimulate further research in this field.

Ultra-High-Performance Liquid Chromatography with Photodiode Array and High-Resolution Time-of-Flight Mass Spectrometry Detectors (UHPLC-PDA-ESI-ToF/HRMS) for the Tentative Structural Characterization of Bioactive Compounds of Salvia verbenaca Extracts in Relation to Their Biological Activities.

Salvia verbenaca of the Lamiaceae family is a Mediterranean plant widely used in the Moroccan traditional folk medicine. The aim of this work was to explore the phytochemical composition of Salvia verbenaca extracts and its antioxidant activity. Separation and identification of the major phytochemicals present in the two hexane and ethyl acetate explored extracts have been achieved through ultra-high-performance liquid chromatography separation technique coupled to photodiode array and high-resolution time-of-flight mass spectrometry detectors. Antioxidant activity of the obtained extracts was evaluated through DPPH• (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azinobis(3-ethylbenzothiazoline6-sulfonic acid) diammonium salt) assays and the obtained results were compared to TROLOX (6-hydroxy2,5,7,8-tetramethylchroman-2-carboxylic acid). Using the analysis technique indicated above, eighteen phytochemicals belonging to phenolic acids, phenolic diterpenes and flavonoids have been characterized on the basis of the obtained UV and mass spectroscopic properties and on the subsequent fragmentations. The antioxidant activity of the explored extracts showed potential scavenging activities compared to TROLOX. A detailed discussion of the attained results has been presented considering the activities observed of each extract. The research herein presented an analysis technique allowing to screen Salvia verbenaca phytochemicals. The explored plant could be considered as a source of functional phenolic compounds. These could be useful for further pharmacological studies such as new drugs design after clinic and its safety evaluation. It is thus hoped that the information presented here might prompt further studies that will possibly lead to development of therapeutic agents from this plant.

Detection, quantification and degradation kinetic for five benzodiazepines using VAUS-ME-SFO/LC-MS/MS method for water, alcoholic and non-alcoholic beverages

Benzodiazepines can make victims more docile, they are frequently used in drug-facilitated crimes, such as robberies and sexual assaults. Therefore, it is essential to develop techniques for determining whether these chemicals are present in relation with illegal activity is crucial. Therefore, to determine the presence of five benzodiazepines (alprazolam, clonazepam, diazepam, lorazepam, and oxazepam) in water, alcoholic beverages, and non-alcoholic beverages, a simple and direct, miniaturized, and effective vortex assisted ultrasound based microextraction using solidification of floating organic droplets (VAUS-ME-SFO) in combination with LC-MS/MS was developed. 1-Undecanol and acetonitrile, respectively, served as the extractant and disperser solvents. Many other parameters affect the efficiency of the developed analytical procedure VAUS-ME-SFO/LC-MS/MS. These parameters were optimized using Plackett Burman Design and Central Composite Design to obtain reliable results. The optimum conditions for the extraction were: 10.0 mL of sample; 180 μL acetonitrile, as a dispersive solvent; 200 μL of 1-undecanol, as an extraction solvent; pH 7; 105 s of vortex agitation; 120 s of ultrasonication application and 3 min of centrifugation at 7000 rpm. The benzodiazepines were separated by a chromatographic separation technique carried out by a UPLC system consisting of a binary mobile phase. The solvent system comprises of 0.1% Formic acid in Milli-Q (Solvent A) and 0.1% Formic acid in ACN (Solvent B) with a gradient flow of 3.5 min total analysis time. Under the optimized conditions, the calibration curve was studied in the range of 0.124–7.810 ng mL−1. The regression correlation coefficient (R2) value of all targeted analytes ranges from 0.993 to 0.999. The LOD and LOQ of VAUS-ME-SFO methods using LC-MS/MS analysis range from 0.316 to 0.968 ng mL−1 and 1.055–3.277 ng mL−1 respectively. The repeatability within a day varied from 0.6 to 3.5%, and the reproducibility across days varied from 2.2 to 6.3%. The recoveries ranges for water, alcoholic and non-alcoholic beverages from 70.77 to 114.53%, 63.20–102.21% and 66.23–113.28% respectively. Further, the degradation kinetics was studied to establish the half-life of each targeted analyte in the matrix undertaken in the study. The water samples were classified based on their BDZs residues. This implies that the more health care and anthropogenic activity, the more the BDZs residue will be in water samples.

An overview of recent progress in multiple dual-mode counter-current chromatography.

Counter-current chromatography is a chromatographic separation and purification technique being developed. The development of different elution modes has significantly contributed to this field. Multiple dual-mode elution is a method developed based on dual-mode elution, which consists of a series of changing cycles of the phase role and the direction by switching between normal and reverse elution modes of counter-current chromatography. This dual-mode elution method takes full advantage of the liquid nature of stationary and mobile phases of counter-current chromatography and effectively improves the separation efficiency. So, this unique elution mode has gained extensive attention for separating complex samples. This review mainly describes and summarizes in detail its development, applications, and characteristics in recent years. Meanwhile, its advantages, limitations, and future outlook also have been discussed in this paper.

Potential of Using Limestone Rocks Accumulated in Al-Samawa Stone Quarry, South Iraq, for The Stationary Phase in A Column Chromatography Separation

This investigation aims to determine whether it is feasible to use the limestone rocks found in the Al-Samawa stone quarry in southern Iraq as the stationary phase in column chromatography separation. Together with the chromatographic application, the physical and chemical characteristics of the rocks are examined. SiO2, SO4, PO4, NO3, and Cl are the negative ions, while Ca, Mg, Na, K, and Li are the positive ions. The limestone samples are characterized via chromatographic analysis. The results suggest that limestone samples could be used as an adsorbent material for chromatographic separation techniques. Additionally, samples from the Nasiriyah refinery's crude oil can be used to separate oil.

Elimination of spectral interference of 87Rb with 87Sr during ICP-MS measurements using a chromatographic technique.

A new chromatographic separation technique was developed for the measurement of the strontium (Sr) isotope abundance ratio using inductively coupled plasma mass spectrometry (ICP-MS). This technique, LC-ICP-MS, utilizes the addition of 18-crown-the eluent and an ODS column. The technique completely eliminates the spectral interference of 87Rb (an isobar of 87Sr) with 87Sr during the ICP-MS measurement. 18-Crown-6 selectively forms a clathrate compound with some metals. When the Sr isotope abundances are measured using LC-ICP-MS with an ODS column, the addition of a specific amount of 18-crown-6 to the HNO3/0.1% methanol eluent elongates the retention time of Rb. Therefore, Rb can be completely separated from Sr using LC because Rb is captured into the 18-crown-6 molecule and forms a clathrate compound. The technique enables the measurement of Sr isotope abundance ratios easily, even in the presence of a large amount of Rb. The proposed technique was applied to the measurement of Sr isotope abundance ratios in rice samples. To validate the LC-ICP-MS technique, a fraction containing Sr was collected, and the 87Sr/86Sr isotope ratio was precisely measured using ICP-MS.

Advances in Mass Spectrometry-Metabolomics Based Approaches.

Highly selective and sensitive analytical techniques are necessary for microbial metabolomics due to the complexity of the microbial sample matrix. Hence, mass spectrometry (MS) has been successfully applied in microbial metabolomics due to its high precision, versatility, sensitivity, and wide dynamic range. The different analytical tools using MS have been employed in microbial metabolomics investigations and can contribute to the discovery or accelerate the search for bioactive substances. The coupling with chromatographic and electrophoretic separation techniques has resulted in more efficient technologies for the analysis of microbial compounds occurring in trace levels. This book chapter describes the current advances in the application of mass spectrometry-based metabolomics in the search for new biologically active agents from microbial sources; the development of new approaches for in silico annotation of natural products; the different technologies employing mass spectrometry imaging to deliver more comprehensive analysis and elucidate the metabolome involved in ecological interactions as they enable visualization of the spatial dispersion of small molecules. We also describe other ambient ionization techniques applied to the fingerprint of microbial natural products and modern techniques such as ion mobility mass spectrometry used to microbial metabolomic analyses and the dereplication of natural microbial products through MS.