Stationary Phase For Chromatographic Separation Research Articles

Separation performances of extended pillar[6]arenes, a new stationary phase for gas chromatography

Pillar[n]arenes (P[n]As, n = 5–10), a new generation of macrocyclic hosts, display interesting properties such as 3D π-electron cavity, host-guest interactions, good stability, and easy functionalization, which make these polymers very promising for separation applications. In particular, extended P[n]As (EP[n]As) show large-sized cavities, structural flexibility, cavity adaptability, and synthetic accessibility. These characteristics have been exploited in this work, which reports for the first time the investigation of two EP[n]As (LP6A-C10 and BpP6A-C10) as stationary phases for gas chromatography (GC). LP6A-C10 and BpP6A-C10 columns exhibited moderate polarity (average polarity 117 and 118) and high column efficiencies (3000 plates/m and 3235 plates/m). These columns achieved complete challenging separation of halogenated benzene, benzaldehyde, phenol, and aniline isomers, which are difficult to resolve due to their high resemblance in structures and properties. Experimental results demonstrate the high selectivity and inertness of the prepared columns and their distinct advantages if compared with commercial HP-5 and HP-35 columns. EP[n]As columns displayed good separation repeatability with RSD values of 0.01%–0.02 % for run-to-run, 0.01%–0.22 % for day-to-day, and 1.36–3.56 % for column-to-column. This work demonstrates the promising future of EP[n]A stationary phases for chromatographic separations.

Esterified styrene-maleic acid copolymer modified silica as mixed-mode polymer-brush stationary phases for chromatographic separation

Styrene-maleic acid (SMA) copolymer has received much attention for its excellent solubilization characteristics. In this work, SMA copolymer brush-based chromatographic stationary phases were exploited and developed for the first time. First, SMA copolymer brush was in situ grown on the surface of spherical silica via living/controlled reversible addition-fragmentation chain transfer (RAFT) polymerization method. Subsequently, as a proof-of-concept demonstration, the copolymer was esterified by diethylene glycol mono-2-ethylhexyl ether (DGME) and 2-(2-ethylhexyloxy) ethanol (EHOE), respectively. The obtained Sil-SMA-DGME and Sil-SMA-EHOE copolymer-brush chromatographic stationary phases were characterized by transmission electron microscopy, Fourier transform infrared spectrometer, X-ray photoelectron spectroscopy, and thermogravimetric analysis, respectively. The chromatographic retention mechanism indicated that both the two packed columns exhibited hydrophilic/reverse mixed-mode retention modes. The maximum column efficiency was up to 71,000 N/m. The chromatographic separation performance evaluation indicated that the novel kind of stationary phases had excellent separation capabilities for hydrophilic, hydrophobic compounds and phospholipid standards. In addition, by combination with mass spectrometry identification, the Sil-SMA-DGME column was further exploited for separation and identification of phospholipids in human lung cancer cells. Totally, 9 classes including 186 phospholipid species were successfully identified. The results demonstrated the promising application prospects of the novel kind of SMA copolymer-brush chromatographic stationary phases.

Room temperature synthesis of a chiral covalent organic framework core-shell composite for high-performance liquid chromatography enantioseparation.

In this article, chiral covalent organic framework core-shell composite CCOF-TpPa-Py@SiO2 was facilely synthesized by induction at room temperature. The CCOF-TpPa-Py@SiO2 core-shell composite was used as a chiral stationary phase for the separation of the racemates by high-performance liquid chromatography, which exhibits good separation performance for chiral compounds including ketones, alcohols, esters, epoxides, carboxylic acids, amides, and amines. The effects of analyte injection mass on the enantioseparation were studied. The reproducibility and stability of the CCOF-TpPa-Py@SiO2 chiral column were explored. The intra-day (n=5), inter-day (n=5), and inter-column (n=3) relative standard deviations for the migration times and resolution of benzoin were 0.32%-0.54%, 0.45%-0.61%, and 1.21%-1.53%, respectively. In addition, the chiral separation ability of the CCOF-TpPa-Py@SiO2 chiral column (column A) was compared with that of the MDI-β-CD-Modified COF@SiO2 (column B) as well as a commercial chiral column (Chiralpak AD-H). The chiral recognition ability of column A is complementary to that of column B and AD-H column. The resolution mechanism of CCOF-TpPa-Py@SiO2 stationary phase towards chiral analyte was explored. Hence, the synthesis of CCOF-TpPa-Py@SiO2 core-shell composite by induction at room temperature as chiral stationary phases for chromatographic separation has important research potential and application prospects.

A minireview on covalent organic frameworks as stationary phases in chromatography.

Advances in the design of novel porous materials open new avenues for the development of chromatographic solid stationary phases. Covalent organic frameworks (COFs) are promising candidates in this context due to their remarkable structural versatility and exceptional chemical and textural properties. In this minireview, we summarize the main strategies followed in recent years to apply these materials as stationary phases for chromatographic separations. We also comment on the perspectives of this new research field and potential directions to expand the applicability and implementation of COF stationary phases in analytical systems.

Dispersive hierarchically porous composites based on defective MOFs as mixed-mode stationary phases for chromatographic separation.

Defective metal-organic frameworks-based composites with excellent separation properties were obtained. The mesoporous metal-organic frameworks were selected and deliberately designed to be deficient, and they were then combined with polyacrylamide to be modified on the surface of silica microspheres. The prepared composites were employed as mixed-mode stationary phase in chromatographic separation, and they were compared to both conventional microporous metal-organic framework-based columns and commercial columns. It showed improved selectivity and retention toward both hydrophilic and hydrophobic analytes, allowing for the effective separation of nine nucleosides and nucleobases, eight alkaloids, six antibiotics, and five alkylbenzenes. Additionally, the column was used to effectively separate the active ingredients in the daring substance of honeysuckle, revealing a wide range of possible applications. For the same batch of analytes, three batches of distinct materials demonstrated consistent separation effects. It also demonstrated excellent chromatographic repeatability and stability, with relative standard deviations of the retention time and/or column efficiency being found to be less than 0.8% and 0.9%, respectively. The dispersive hierarchically porous composites were demonstrated to be effective in chromatographic separation, and the results expanded the potential uses of defective MOFs with dispersed multi-level pores.

High-resolution performance of pillar[6]arene functionalized with imidazolium ionic liquids for gas chromatography

Pillar[n]arenes (P[n]A, n = 5–10) have attracted much attention because of their highly symmetric pillar-shaped architecture with π-electron rich cavity. Nevertheless, the use of ionic liquid functionalized P[n]A in chromatography has not been reported up to data. This work reports the investigation of the imidazolium ionic liquids functionalized pillar[6]arene (P6A-C10-IM-C8[NTf2]) as the stationary phase for gas chromatography (GC). The statically coated P6A-C10-IM-C8[NTf2] column (0.25 mm i.d.) showed moderate polarity and high column efficiency of 4733 plates/m determined by n-dodecane at 120 °C (k = 2.29). Owing to its unique amphiphilic conformation, the P6A-C10-IM-C8[NTf2] showed good column inertness and resolving capability for a wide range of analytes and isomers. Particularly, the P6A-C10-IM-C8[NTf2] column exhibited distinctly advantageous performance for the challenging isomers of halogenated benzenes, benzaldehydes, phenols and anilines over the common commercial columns, namely 5% phenyl methyl polysiloxane (HP-5) and 35% phenyl methyl polysiloxane (HP-35). In addition, it exhibited good column repeatability and reproducibility with RSD values on the retention times less than 0.05% for run-to-run, 0.38% for day-to-day and 2.94% for column-to-column, respectively. This work demonstrates the promising future of ionic liquid P[n]A stationary phases for chromatographic separations.

Multipurpose new gas chromatography column based on pillararenes functionalized with imidazolium ionic liquids

BackgroundGas chromatography is worldwide recognized as one of the most important analytical techniques, due to its high versatility and reliability. The heart of a gas chromatograph is the column, that allows analyte peak separations and, consequently, accurate qualitative and qualitative analyses. New and more efficient columns are always requested to satisfy new and challenging analytical needs. ResultsIn this work, imidazolium ionic liquids functionalized pillar [5] arenes have been used for the first time as gas chromatographic stationary phases, considering their highly symmetric pillar-shaped architecture with cavities rich in π-electrons. Four imidazolium ionic liquids functionalized pillar [5] arenes have been tested as stationary phases with numerous analytes and isomers. In particular, one of these showed superior performances if compared to commercial columns, enabling challenging isomeric separations of halogenated benzenes, aromatic aldehydes, and aromatic anilines. Significance and noveltyTo our knowledge, this is the first report on the use of the ionic liquid P[n]A as a stationary phase in chromatography, either in GC or liquid chromatography (LC) separations. This work demonstrates the promising potential of ionic liquid P[n]A stationary phases for chromatographic separations.

Simultaneous Determination of Two Metabolites of Gelsemium elegans by LC-MS/MS in Rat Urine and its Application to Pharmacokinetic Study

Background: G. elegans is a highly useful medicinal plant with broad and superior clinical pharmacological effects. However, it also exhibits high toxicity to humans, so it must be used with extreme caution in clinical practice. Previous studies on G. elegans have mainly focused on its main ingredients from perspectives of pharmaceutical analysis, pharmacokinetics, and pharmacodynamics. The kinetic behavior of G. elegans' main metabolites in vivo has not yet been reported, which is also crucial for studying the herb's toxification and detoxification process. Aims: This study aimed to establish a quantitative method to describe the metabolic profile of the two main metabolites of koumine after oral administration of G. elegans to rats. Objective: The objective of this study was to test two major metabolites of G. elegans in rat urine after administration using a rapid and sensitive high-performance liquid chromatographic-tandem mass spectrometric (HPLC-MS/MS) method developed in advance. Methods: A Kromasil C18 column was used as the stationary phase for chromatographic separation, with an isocratic mobile phase consisting of mixture of water (2 mM ammonium formate), formic acid, and methanol (25:0.05:75, v/v/v) at a flow rate of 0.40 mL/min. The mass spectrometer was equipped with an electrospray ionization (ESI) source operating in positive ionization mode, and detection was performed using a selective reaction monitoring (SRM) mode. Detection was performed in selective reaction monitoring (SRM) mode. Protein precipitation was used to pretreat the rat urine samples before analysis, with acetonitrile as the precipitation solvent. In this study, a "relative quantification" strategy was employed, which avoided the expensive and time-consuming separation of standard substances. The assay was validated in terms of specificity, linearity, precision, stability, recovery, and other aspects. Results: The intra- and inter-day precision values were less than 12.7%. The recoveries at three different concentrations were all above 73.1%. The stability study showed that the analytes were stable during the experiment. The method was then used to study the kinetic profiles of N-demethylkoumine and N-oxidatekoumine in rat urine for the first time. Conclusion: In this study, the established LC/MS method was fully validated and proven to be sensitive and accurate for the simultaneous determination of the two main metabolites of G. elegans in rats' urine samples. These results could provide references for the safe use of koumine and G. elegans in clinical applications.

A green reversed phase HPLC and HPTLC methods and their validation for simultaneous estimation of remogliflozin, vildgliptin and metformin in fixed dose combination formulation

To estimate remogliflozin, vildagliptin and metformin in a new fixed dose combination two chromatographic methods were developed and validated. The initial method is a green RP- HPLC method which uses a (150 × 4.6) mm, 2.7 mm C18 column, Ascentis as stationary phase for chromatographic separation and mobile phase made up of acetonitrile (ACN) and phosphate buffer in a ratio of 35:65 by volume. A PDA detector was used for quantification at 220 nm. 1.5 mL/min is the flow rate. Linearity was observed at 62.5–375 µg/mL, 6.25–37.5 µg/mL and 12.5–75 µg/mL for remogliflozin, vildagliptin and metformin respectively. A subsequent technique developed is HPTLC densitometric method which was also found as greener method for the separation and quantification of the three analytes in which pre-coated silica gel 60F254 aluminum plates were taken as stationary phase and the mobile phase contain phosphate buffer: ACN: glacial acetic acid in the ratio of 3: 7: 0.2 by volume. The densitometric measurements were achieved at a wavelength of 205 nm. Linearity was observed at concentrations 200–600 ng/spot, 20–60 ng/spot, 40–120 ng/spot for metformin, vildagliptin and remogliflozine respectively. Mean % recovery was 98.92–100.41% for remogliflozin, 99.92–100.33% for vildagliptin and 99.17–100.19% for metformin. The method was tested precise, specific and robust.

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.

Adsorption of actinides (Ⅲ) and lanthanides (Ⅲ) on silica-based BCPDTPA resin: Kinetics, thermodynamics, and isotherms

To minimize the long-term radiological risk and improve the accuracy of radioactive analysis, isolation of trivalent actinides and lanthanides is very necessary and much more challenging due to their similar chemical properties. Herein, the adsorption performance and mechanism of a novel porous BCPDTPA/SiO2-P extraction resin towards trivalent actinides (Am) and lanthanides (Eu) was investigated. The effects of adsorption parameters such as contact time, HNO3 concentration, temperature, and Eu concentration on the adsorption were conducted by batch adsorption experiments. The adsorption mechanism of Am(Ⅲ) and Eu(Ⅲ) by BCPDTPA/SiO2-P resin was elucidated based on kinetics, thermodynamics, and isotherms analysis. The results showed that BCPDTPA/SiO2-P resin has a high affinity for Am(Ⅲ) compared to Eu(Ⅲ) within the range of experimental conditions. Kinetic studies revealed that the resin was in accordance with the pseudo-second-order equation by chemisorption as the rate-limiting step of the adsorption process. Thermodynamic parameters indicated that the adsorption was spontaneous and endothermic process. The adsorption isotherm followed the Freundlich isotherm model. As a result, the use of BCPDTPA/SiO2-P resin as a stationary phase for chromatographic separation of actinides(Ⅲ)/lanthanides(Ⅲ) can be expected due to its clear adsorption mechanism and selectivity.

Synthesis of C8F13-SiO2 stationary phase for chromatographic separation of highly polar compounds

Up to now, the chromatographic separation and analysis of highly polar compounds are still challenging because of low retention ability and selectivity of conventional stationary phases (SPs). Developing new SPs to achieve high-resolution and high-efficiency separation of polar compounds is of great importance for health and medicine, food safety, environmental protection, etc.. Herein, an influential multi-step modification strategy (modification with 1H,1H,2H,2H-perfluorooctyltriethoxysilane on the silica twice and end-capped with trimethylchlorosilane once) is introduced to prepare C8F13-SiO2 SP. The physical properties of C8F13-SiO2 SP, including morphologies, pore structures and carbon content were fully characterized by various instrumental techniques. The packed HPLC column with C8F13-SiO2 SP exhibited high column efficiency, good peak shape (tailing factors for most analytes are between 0.9 and 1.3), and resolution for simultaneous separation of ginsenosides, sulfonamides, nucleosides, and benzoylurea insecticides (BUs); meanwhile, the retention mechanism of typical reversed-phase liquid chromatography (RPLC) mode was observed. A column efficiency of 30,220 plates/m for separation of ginsenoside Re was obtained. Furthermore, the resulting columns benefit from the advantages of supreme reproducibility, repeatability and stability. Importantly, the chromatographic properties (e.g. column efficiencies, chromatographic peak shapes, retention ability and resolution) of the C8F13-SiO2 SP for the polar analytes were superior to those of the commercial SPs (including commercial amino-modified silica SP, diol-modified silica SP and commercial PFP-SiO2 SP). Thus, the C8F13-SiO2 SP is able to satisfy the strict requirements of highly polar compounds separation.

Separation of p-xylene and m-xylene by simulated moving bed chromatography with MIL-53(Fe) as stationary phase

The separation of p-xylene (PX) and m-xylene (MX) isomers with near boiling points is a worldwide problem. The metal-organic framework material is an ideal stationary phase for chromatographic separation because of its high porosity, homogeneous pore diameter and good chemical stability. In this paper, a simulated moving bed (SMB) chromatography system with MIL-53(Fe) as the stationary phase and petroleum ether-dichloromethane as the mobile phase was designed to separate PX and MX at ambient temperature. Firstly, according to the elution curves of a single column, nonlinear competitive Langmuir adsorption isotherm equation was confirmed by equilibrium dispersive chromatography model. Then, the SMB separation zone was determined based on triangle theory, and the SMB operating conditions were optimized. Finally, the purity, recovery and productivity of PX reached 100.0%, 99.1% and 93.1 g/L/h, respectively; the purity, recovery and productivity of MX reached 96.4%, 100.0% and 23.5 g/L/h, respectively; the solvent consumption was 0.42 L/g.

Core-shell MOFs-based composites of defect-functionalized for mixed-mode chromatographic separation

The micropores of the metal-organic frameworks (MOFs) endow with the advantages of size selectivity and large specific surface area, etc., but they limit their applications toward the control of diffusion and transport processes. Here, we report a strategy to prepare the hierarchical porous material, functional defect, which allows incorporation of L-Cysteine in the MOF by defect-loading. Silica microspheres were modified with these materials to form core-shell composites and used as mixed-mode stationary phases for chromatographic separations. Compared with the traditional MOFs-based stationary phase, it exhibited superior efficiency and selectivity for separation of various analytes and highlighted the role of defect of MOFs and function of L-Cysteine. In addition to the rapid separation of hydrophobic compounds, the stationary phase showed great potential in the separation of hydrophilic analytes, especially for separation of ten carbohydrates and eight sulfonamides. It showed excellent chromatographic reproducibility and stability, and the repeatability of preparation was investigated by relative standard deviations of retention time and/or column efficiency of objective compounds, which was among different batches less than 1.81%. This demonstration provided deep understanding of separation mechanism between MOF-based composites with functional defect and analytes, and stimulated the wide applications of such defective MOFs complexes in separations and analysis.

Recent trends on the implementation of reticular materials in column-centered separations.

Advances in the development of column‐based analytical separations are strongly linked to the development of novel materials. Stationary phases for chromatographic separation are usually based on silica and polymer materials. Nevertheless, recent advances have been made using porous crystalline reticular materials, such as metal‐organic frameworks and covalent organic frameworks. However, the direct packing of these materials is often limited due to their small crystal size and nonspherical shape. In this review, recent strategies to incorporate porous crystalline materials as stationary phases for liquid‐phase separations are covered. Moreover, we discuss the potential future directions in their development and integration into suitable supports for analytical applications. Finally, we discuss the main challenges to be solved to take full advantage of these materials as stationary phases for analytical separations.

Two-dimensional MOF Cu-BDC nanosheets/ILs@silica core-shell composites as mixed-mode stationary phase for high performance liquid chromatography

Here, silica microspheres were decorated with two-dimensional metal–organic frameworks (2D MOFs) nanosheets and ionic liquids, and evaluated as the mixed-mode stationary phase for chromatographic separation. The ionic liquids were used to assist the synthesis of 2D MOFs nanosheets, and also acted as adhesives among the nanosheets and silica. In contrast with the 2D MOFs-based column without ionic liquids and commercial columns, the prepared column exhibited enhanced chromatographic separation performance for partially hydrophilic compounds such as alkaloids, sulfonamides and antibiotics, etc. In addition to excellent chromatographic repeatability and stability, it has also been verified that the composites could be easily and repeatedly prepared. The relative standard deviation of the retention time of the same type of analyte between the three batches of materials was ranging from 0.21% to 1.7%. In short, these results indicated that the synthesized composites were promising separation material for liquid chromatography, which made it possible to broaden the application of 2D MOFs in the field of chromatography.

Fabrication of two-dimensional metal-organic framework nanosheets/PDA composites as mixed-mode stationary phase for chromatographic separation.

Thesynthesis of two-dimensional metal-organic frameworks (2D MOFs)/polymer core-shell compositesis reported which were composed of polydopamine modified 2D Zr-1,3,5-(4-carboxylphenyl)-benzene (2D Zr-BTB) nanosheets and silica microspheres via a double-solvent approach. In this way, the composites were obtained under the condition of two solvents with different polarities to avoid agglomeration and uneven modification of most MOFs particles on the surface of the silica, existing inevitably in the one-pot method. Compared with the reported MOFs@silica composites adopting one-pot solvent method, the prepared composites exhibited significantly enhanced separation performance for sulfonamides, antibiotics, nucleosides, and polycyclic aromatic hydrocarbons compounds. Furthermore, the retention mechanisms were demonstrated by studying the relationships of chromatographic retention factors of tested analytes versus a variety of parameters under RPLC and HILIC modes, respectively. The superior chromatographic repeatability and stability were validated through the relative standard deviations of the retention time and/or column efficiency, which were found to be less than 0.8% and 0.9%, respectively. The material showed efficient separation ability for several types of compounds and provided another selectivity for preparing composites based on 2D MOFs nanosheets and other functional molecules.

Simultaneous quantification of empagliflozin, linagliptin and metformin hydrochloride in bulk and synthetic mixture by RP\u2013LC method

BackgroundExtensive literature review revealed that no RP–LC method has been developed for simultaneous estimation of EMPA, LINA and MET in combined dosage form. This is a newer combination approved by USFDA on 4th June 2019 and it is launch in the United State Market on 27th January 2020.ResultA simple, sensitive, specific, precise and accurate reverse phase—high performance liquid chromatography (RP- HPLC) method has been developed for simultaneous estimation of Empagliflozin, Linagliptin and Metformin HCl in bulk and synthetic mixture. Phenomenex C18 column (250 mm × 4.6 mm, 5 µm) was used as stationary phase for chromatographic separation through isocratic elution using Acetonitrile: Methanol: Water in a ratio (27: 20: 53, v/v/v) pH 4 adjusted with 1% Ortho-phosphoric acid as mobile phase at flow rate 1 ml/min. PDA detector was used for simultaneous analysis of all three drugs at common wavelength 223 nm and the each injection volume was 20 µl. The linearity range for Empagliflozin, Linagliptin and Metformin HCl was found to be 0.5–5 µg/ml, 0.25–2.5 µg/ml, and 50–500 µg/ml, respectively. The retention time for Empagliflozin, Linagliptin and Metformin HCl was found to be 14.5 min, 3.4 min and 2.01 min, respectively. The percentage (%) recovery was found to be 99.98–100.81% for Empagliflozin, 99.33–100.57% for Linagliptin and 100.65–101.35% for Metformin HCl respectively.ConclusionAs per the international Conference on Harmonisation (ICH) Q2 (R1) guideline, proposed RP–LC method validation has been carried out. The proposed RP–LC method was repeatable and selective as per statistical analysis and it can be use for simultaneous estimation of Empagliflozin, Linagliptin and Metformin HCl in bulk and synthetic mixture. The proposed method might be applied for simultaneous estimation of all three drugs in pharmaceutical formulation.

Development of a multiclass method to quantify phthalates, pharmaceuticals, and personal care products in river water using ultra-high performance liquid chromatography coupled with quadrupole hybrid Orbitrap mass spectrometry.

The organic micropollutants such as phthalates, pharmaceuticals, and personal care products (PPPCPs) enter the surface water through various routes. The aim of this study is to develop a sensitive and efficient method to identify and quantify 26 PPPCPs found in river water with acceptable accuracy and precision using a liquid chromatograph hyphenated with quadrupole hybrid Orbitrap mass spectrometry (Q-Orbitrap-MS) in a single chromatographic run. The organic micropollutants were extracted from river water by solid-phase extraction (SPE) using hydrophilic-lipophilic balance sorbent and analyzed using an ultra-high performance liquid chromatograph (UHPLC) equipped with C18 stationary phase for chromatographic separation. The targeted mass experiments were conducted in a Q-Orbitrap-MS system in positive and negative electrospray ionization mode. The method was found to be linear in the concentration range of 1-125ng/L with coefficient of determination lying in the range of 0.995-0.999. The method achieved limit of quantification in the range of 0.41-1.72ng/L, and method recovery measured at three different concentrations was found to be in the range of 75-115%. Intra- and interday precision expressed as percent relative standard deviation was found to be<15%. Matrix effect was found to be in the range of 83.5-109.79%. The matrix match calibration was used for quantification of PPPCPs in river water sample. The method performance was evaluated by analyzing real samples collected from Ganga River, and the concentrations of 21 analytes were found to be in the range of 0.76-9.49ng/L for pharmaceuticals, 1.49-8.67ng/L for phthalates, and 0.9-7.58ng/L for personal care products. The present method was found to be precise, sensitive, and rapid to determine 26 PPPCPs including phthalates in river water samples using SPE-UHPLC-Q-Orbitrap-MS.

Investigation of the Separation Efficiency of Tube Radial Distribution Chromatography with Stationary Outer Phase Using the van Deemter Equation

The outer phase in tube radial distribution chromatography (TRDC) operated as a stationary phase in chromatographic separation. Chromatographic peak information from model analytes 1-naphthol, 1-naphthalenesulfonic acid, 2,6-naphthalenedisulfonic acid, and 1,3,6-naphthalenetrisulfonic acid was examined using TRDC at various flow rates, using a fused-silica capillary tube (inner diameter, 75 μm; length, 120 cm; effective length, 100 cm) as the separation column and water/acetonitrile/ethyl acetate (3:8:4, v/v/v) as eluent. From the data, the relationships between average linear velocities and values of height equivalent to one theoretical plate of the analytes were investigated, and the separation efficiency by TRDC, comprising an inner phase (mobile phase) and outer phase (stationary phase) in an open-tubular capillary tube, was examined using the van Deemter equation.