Capillary Electrophoretic Method Research Articles

CE-MS and CE-MS/MS for the multiattribute analysis of monoclonal antibody variants at the subunit level

The analysis of product-related substances and impurities is a critical step in the biopharmaceutical quality control of multiattribute monoclonal antibodies (mAbs), as posttranslational modifications or other variants can influence the product's biological activity. Many approaches are available for variant analysis; however, they are either variant-specific, mAb-specific, time-consuming, or require expensive equipment. Here, we present a generic capillary electrophoretic method based on a neutral-coated capillary which was coupled to mass spectrometry (MS) via the nanoCEasy interface for mAb variant analysis at the subunit level (enzymatically digested and reduced mAb). The method enabled the separation of several (i) size variants (e.g. glycosylation variants) and (ii) charge variants (e.g. c-terminal lysin clipping) as well as (iii) multiple other proteoforms (e.g. additional glycation) and (iv) incompletely reduced subunits. Separated variants were confirmed by MS/MS fragmentation even for small mass deviations like deamidation or open disulfide bridges. The system, initially developed for one mAb, was tested with nine other IgG1s to show the general applicability of the system. The presented multiattribute method enables fast and detailed characterization of mAb variants with little sample preparation and relatively simple separation equipment enabling the separation of a large set of mAb variants.

Simultaneous Determination of Glycerol and Carbohydrates in Sweat by Capillary Electrophoresis with Amperometric Detection

Background: Glycerol, sucrose, lactose, glucose, and fructose are important biomarkers in human sweat because their contents can reflect physiological status and health conditions. It is of high importance to determine them in sweat for health monitoring, disease diagnosis, physical training, etc. Aim: The aim of this work is to develop a method based on capillary electrophoresis and amperometric detection for the simultaneous determination of glycerol and carbohydrates in sweat. Objective: A capillary electrophoretic method based on pipette-tip-based detection electrodes and micro-injectors was developed for the simultaneous determination of glycerol, sucrose, lactose, glucose, and fructose in sweat samples Method: Sweat samples diluted in the background electrolyte of 75 mM NaOH aqueous solution were electrokinetically introduced into a piece of separation capillary via pipette tip-based microinjectors. Glycerol, sucrose, lactose, glucose, and fructose were determined by capillary electrophoresis in combination with a pipette-tip-based copper electrode. Results: At a DC voltage of 12 kV, the capillary electrophoretic separation of the five analytes could be achieved in less than 11 min in a piece of 40 cm long fused silica capillary containing 75 mM NaOH aqueous solution. Linearity was observed between the currents and concentrations, with the limits of detection ranging from 0.21 to 0.72 µM at a detection potential of 0.65 V. Glycerol, sucrose, lactose, glucose, and fructose in sweat samples were positively identified and accurately measured. Conclusion: The method was successfully applied in the simultaneous determination of glycerol and carbohydrates in sweat samples with satisfactory assay results. It will find a wide range of applications in clinical diagnosis, health monitoring, and drug and food analysis.

Identification and quantification of chain-pairing variants or mispaired species of asymmetric monovalent bispecific IgG1 monoclonal antibody format using reverse-phase polyphenyl chromatography coupled electrospray ionization mass spectrometry

Developing a knob-into-hole asymmetric bispecific IgG1 monoclonal antibody (mAb) poses manufacturing challenges due to the expression of chain pairing variants, also called mispaired species, in the desired product. The incorrect pairing of light and heavy chains could result in heterogeneous mispaired species of homodimers, heterodimers, light chain swapping, and low molecular weight species (LMWS). Standard chromatography, capillary electrophoretic, or spectroscopic methods poorly resolve these from the main variants. Here, we report a highly sensitive reverse-phase polyphenyl ultra-high-performance liquid chromatography (RP-UHPLC) method to accurately measure mispaired species of Duet mAb format, an asymmetric IgG1 bispecific mAb, for both process development and quality control analytical tests. Coupled with electrospray ionization mass spectrometry (ESI-MS), it enabled direct online characterization of mispaired species. This single direct assay detected diverse mispaired IgG-like species and LMWS. The method resolved eight disulfide bonds dissociated LMWS and three mispaired LMWS. It also resolved three different types of IgG-like mispaired species, including two homodimers and one heterodimer. The characterization and quantification simultaneously enabled the cell line selection that produces a lesser heterogeneity and lower levels of mispaired species with the desired correctly paired product. The biological activity assessment of samples with increased levels of these species quantified by the method exhibited a linear decline in potency with increasing levels of mispaired species in the desired product. We also demonstrated the utility of the technique for testing in-process intermediate materials to determine and assess downstream purification process capability in removing diverse mispaired IgG-like species and LMWS to a certain level during the downstream purification process. Our investigation demonstrates that adopting this method was vital in developing asymmetric bispecific mAb from the initial stage of cell line development to manufacturing process development. Therefore, this tool could be used in the control strategy to monitor and control mispaired species during manufacturing, thus improving the quality control of the final product.

CE-MS/MS and CE-timsTOF to separate and characterize intramolecular disulfide bridges of monoclonal antibody subunits and their application for the assessment of subunit reduction protocols

Characterization at the subunit level enables detailed mass spectrometric characterization of posttranslational modifications (PTMs) of monoclonal antibodies (mAbs). The implemented reduction often leaves the intramolecular disulfide bridges intact. Here, we present a capillary electrophoretic (CE) method based on a neutral-coated capillary for the separation of immunoglobulin G-degrading enzyme of Streptococcus pyogenes (IdeS) digested and reduced mAb subunits followed by mass spectrometry (MS), MS/MS identification, and trapped ion mobility mass spectrometry (timsTOF). Our CE approach enables the separation of (i) different subunit moieties, (ii) various reduction states, and (iii) positional isomers of these partly reduced subunit moieties. The location of the remaining disulfide bridges can be determined by middle-down electron transfer higher energy collisional dissociation (EThcD) experiments. All these CE-separated variants show differences in ion mobility in the timsTOF measurements. Applying the presented CE-MS/MS method, reduction parameters such as the use of chaotropic salts were studied. For the investigated antibodies, urea improved the subunit reduction significantly, whereas guanidine hydrochloride (GuHCl) leads to multiple signals of the same subunit in the CE separation. The presented CE-MS method is a powerful tool for the disulfide-variant characterization of mAbs on the subunit level. It enables understanding disulfide bridge reduction processes in antibodies and potentially other proteins.

Green inexpensive capillary electrophoretic method for the determination of Eszopiclone in pharmaceutical preparations

Green inexpensive capillary electrophoretic method for the determination of Eszopiclone in pharmaceutical preparations

Validated green high performance liquid chromatographic and capillary electrophoretic methods for estimation of dinitolmide in presence of its acid-degradation product

This study describes two new, green, fast, specific and highly sensitive stability-indicating techniques for determination of Dinitolmide (DM) in presence of its acid induced degradation product without prior separation; Acid degradation was carried out by hydrolysis with 0.1 N HCl; and the acidic degradation pathway was established by IR, and MS techniques. The first is a HPLC-Diode Array detector was performed by isocratic mode on BDS Hypersil C18 column (150 mm × 4.6 mm × 5 μm particle size) at ambient temperature with a mobile phase consisting of 5 mM sodium acetate buffer (pH 5.5): acetonitrile (40:60, v/v), flow rate of 1 mL/min and detection at 210 nm. DM and its acid degradant were eluted at 4.3 and 2.8 min, respectively offering quick analysis. Linearity of the calibration curves confirm good correlation in range of 1–15 μg/mL with recovery % of 100.02 ± 0.460. The LOD and LOQ were 0.243 and 0.737, respectively. The second method is CE -Diode Array detector was carried out at 25 °C using borate buffer (30 mM, pH 9) as background electrolyte solution and detection at 225 nm. The migration times were 2.26 and 2.97 min for DM and its acid degradant, respectively. The linearity range was 5–50 μg/mL with recovery % of 99.55 ± 0.910, LOD and LOQ were 1.010 and 3.050, respectively. The small LOD and LOQ values for both methods confirm high sensitivity of the methods The developed methods were validated according to the ICH guidelines demonstrating good accuracy and precision. The results were statistically compared with those obtained by a reported method in terms of accuracy, precision, and no significant difference was found. Both methods were successfully applied for estimating DM and its acid degradant in pure and pharmaceutical dosage forms. In addition, the methods were assessed for their greenness profile and CE was greener owing to using safer solvents and less energy consumption.

Development of a capillary electrophoretic method for determination of ketorolac enantiomers in human plasma using cationic β-cyclodextrin derivative as a chiral selector.

A novel approach for the separation of ketorolac enantiomers by capillary electrophoresis is presented. A cationic β-cyclodextrin derivative based on imidazole was synthesized and used as a chiral selector in the background electrolyte. The influence of pH and ionic strength of background electrolyte, as well as cationic β-cyclodextrin derivative concentration on the resolution of ketorolac enantiomers, was investigated. The highest value of the resolution for ketorolac enantiomers was 1.46 when the background electrolyte consisted of 25mM NaH2 PO4 (pH 6.4) with 1mM 1-butyl-3-β-cyclodextrinimidazolium tosylate. Additionally, the possibilities of cationic derivatives for the separation of ketoprofen enantiomers were shown (peak resolution 1.06). The two-step preconcentration mode was developed to reduce the limit of detection of individual enantiomers. The proposed approach was successfully applied to determine ketorolac enantiomers in tablet "Ketorol express" and human plasma. The calibration range of ketorolac enantiomers for plasma samples was 0.25-2.50μg/ml with coefficients of determination ≥ 0.99. The relative standard deviation both of the peak area and migration time was less than 15%, as well as the accuracy ranged from 90.1% to 110.2% for both analytes. The limits of detection were 44 and 55ng/ml for R- and S-ketorolac. The quantity of ketorolac in plasma was verified with high-performance liquid chromatography.

Formulation and Evaluation of Analytical Methods for Determination of Indacaterol

Abstract: Indacaterol is a novel class of β2 adrenoreceptor -agonist used to treat chronic obstructive pulmonary disease. Various analytical methods used for the estimation of Indacaterol have been reviewed in this project. These methods include Ultraviolet Spectrometric method, High Performance Liquid Chromatography method, Capillary electrophoretic method, TLC densitometric method for qualitative and quantitative estimation of Indacaterol in pharmaceutical formulation

Classification of clinical Cutibacterium acnes isolates at phylotype level by capillary electrophoretic methods in roughened fused silica capillary

Despite being commensal bacterium involved in the maintenance of healthy skin, Cutibacterium acnes is also associated with inflammatory diseases. Since inflammatory and immunogenic properties vary between C. acnes phylotypes, reliable classification of clinical C. acnes isolates is important for determining their pathogenicity. Combination of optimized separation methods, polymer-enhanced transient isotachophoresis and sweeping of the charged bacterial cells in micellar electrokinetic chromatography in the roughened fused silica capillary, was used for the separation of twenty clinical C. acnes isolates. Their correct classification into the individual phylotypes was achieved in 20 min at laboratory temperature. In addition, decrease in the separation temperature to 15 °C led to the separation of the individual isolates of some phylotypes. Relative standard deviations of migration times of both intra- and inter-day analyses did not exceed 1.7%. Linearity of the proposed method in the concentration range from 5 × 105 to 1 × 107 cells mL−1 was characterized by the coefficient of determination R2 = 0.9985. Limit of detection of 5 × 105 cells mL−1 (50 cells in 100 nL of the injected sample) was determined for all the examined bacteria.

A novel and simple dynamic coating capillary electrophoresis method for the chiral separation and quantification of mitiglinide enantiomers using hydroxyethyl cellulose as a dynamic coating agent.

A capillary electrophoretic method for the chiral separation and quantification of mitiglinide (MTG) enantiomers is described (less than 9.5 min) with resolution value Rs = 5.25 and with excellent peak shapes after performing the dynamically coating for the bare fused capillary. The study aims to develop and validate a novel and simple method for the separation and quantification of MTG enantiomers using CE after dynamic coating the capillary wall using the hydroxyethyl cellulose (HEC) coating agent. Dynamic coating procedure of the capillary inner surface is conducted via rapid flushes using 0.1 M sodium hydroxide, water, and aqueous solution containing HEC, and hydroxypropyl-γ-cyclodextrin (HP-γ-CD). Besides buffer was used for the dynamic coating process in addition to its use as the separation medium. When the dynamic coating was used, peak symmetry was improved. A bare fused-silica capillary was used throughout the separation after being coated using HEC dissolved in the background electrolyte (BGE) of 50 mM Na₂HPO₄ - 1 M H₃PO₄ solution; pH 8.5; containing 25 25 mg mL-1 of each HP-γ-CD and HEC. The dynamic coating procedure achieved an improvement in migration time as well as peak area precision. The adsorbed coating agent showed slight interactions with MTG, providing efficient separation with outstanding durability and reproducibility at slightly alkaline conditions (pH 8.5). Acceptable validation criteria for selectivity, linearity, precision, and accuracy were also studied. The newly developed method was effectively applied to the assay of enantiomers of MTG in pharmaceutical formulations. Additionally, it was proven to have the advantages of being simple, rapid, and accurate.

Cationic electrophoretic focusing on inverse electromigration dispersion profile with ESI-MS detection. New capillary electrophoretic method for high-sensitivity analysis of 2-hydroxy-s-triazines in waters

Electrophoretic focusing on an inverse electromigration dispersion profile is a relatively new electrophoretic separation method for the analysis of ionisable analytes. Although it offers alternative selectivity, powerful concentration capability and high sensitivity, so far only several systems for the analysis of anionic compounds were reported. This work describes for the first time a functional electrolyte system for the separation of cationic analytes by this method. Based on computer simulations and calculations, a functional electrolyte system was designed, based on 1-ethylpiperazine and pivalic acid. It is suitable for the analysis of weak bases with pKa values between 4.5 and 6 and due to the volatility of both components, it can be operated in combination with ESI-MS detection. Its practical applicability is demonstrated on direct analysis of four 2-hydroxy-s-triazines in waters. Separation in an uncoated capillary with application of negative pressure at the inlet provides very satisfactory results with good reproducibility of peak areas, peak heights and detection times, and with LODs at the 0.5–1 nM (100 ngL−1) level. The robustness of the method is shown on analyses of real tap and river water samples used without any pretreatment.

Loratadine.

Loratadine, 4-(8-Chloro-5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene)-1-piperidinecarboxylic acid ethyl ester, is an antihistamine drug with long-acting effects and has limited selectivity for peripheral H1 receptors. It is widely used for the prevention of allergic diseases such as rhinitis chronic urticaria, and asthma. This chapter discusses, by a critical extensive review of the literature, the description of loratadine in terms of its names, formulae, elemental composition, appearance, methods of preparation. The profile contains physicochemical properties of Loratadine, including pKa value, solubility and X-ray powder diffraction. In addition, it involves Fourier transform infrared spectrometry, nuclear magnetic resonance spectroscopy and mass spectroscopy for functional groups and structural confirmation of. The chapter also includes methods of analysis of the drug such as compendial, titrimetric, electrochemical, spectroscopic, chromatographic and capillary electrophoretic methods. The chapter also covers clinical applications of the drug such as its uses, doses, ADME profiles and mechanism of action.

Classification of Clinical Cutibacterium Acnes Isolates at Phylotype Level by Capillary Electrophoretic Methods in Roughened Fused Silica Capillary

Classification of Clinical Cutibacterium Acnes Isolates at Phylotype Level by Capillary Electrophoretic Methods in Roughened Fused Silica Capillary

Comparative Determination of Melittin by Capillary Electrophoretic Methods

Bee venom from honey bees (Apis Mellifera L.) is known to have many pharmacological and biological properties. Melittin, a peptide consisting of 26 amino acids, is known as the main component of bee venom. The study aims to develop a rapid capillary electrophoresis method for separating and quantifying melittin in honeybee venom. Since melittin is a basic peptide, it will adhere to the capillary wall during separation. Two different methods were developed in this study for the capillary electrophoretic separation of melittin. As a first approach, a low pH buffer system was used. For the second approach, the capillary column was coated with a positively charged polymer (PEI). With both methods developed, the migration of melittin in the capillary was achieved by preventing wall adsorption. Melittin migrated in 6 min when the low-pH buffer system was applied, whereas its migration time is longer than 10 min in the PEI-coated capillary column. Thus, a low-pH buffer system was preferred for the analysis of the actual bee-venom sample. 100 mmol L-1 phosphoric acid/sodium dihydrogen phosphate system at pH 1.55 was chosen as separation buffer. As a conclusion, a fast and reliable method was developed for the determination of melittin in honeybee venom. The method was applied to an Anatolian bee venom sample to highlight the melittin amount. The melittin amount was found as 24.5 ± 3.4 g 100 g-1 in the bee venom sample.

Development of a Capillary Electrophoretic Method for the Determination of Huperzine A Concentration in Vietnamese Huperzia serrata

Huperzine A, isolated from Huperzia serrata, is a potent, specific, and reversible inhibitor of acetylcholinesterase with high efficiency and low toxicity. To evaluate the presence of huperzine A in Vietnamese H serrata, a reliable capillary zone electrophoresis method was developed. The analytical conditions were established using 80 mM ammonium acetate buffer, pH 6.0, hydrodynamic injection at 50 mbar for 5 s, applied voltage of 20 kV, temperature at 25 °C, uncoated fused-silica capillary, 56 cm (50 cm effective length) × 70 µm inner diameter, and ultraviolet detection at 310 nm. The recovery rates ranged from 98.05% to 100.64%, with a relative standard deviation <2%. Good linear regression was observed in the concentration range of 1 to 500 µg/mL, with a correlation coefficient of 0.9994. The limit of detection and limit of quantification were 0.33 and 1.0 µg/mL, respectively. These results demonstrate that this method is simple, selective, and suitable for performing quality control for huperzine A derived from Vietnamese H serrata.

Combined use of β-cyclodextrin and ionic liquid as electrolyte additives in EKC for separation and determination of carob's phenolics-A study of the synergistic effect.

In this work, a simple, reliable, and fast capillary electrophoretic method was developed and validated for the simultaneous determination of 12 polyphenolic compounds, the most frequently found in carob's pulp and seeds. The present work deals with the development of a novel dual electrophoretic system based on the combined use of β-CD and ionic liquid (IL) as buffer additives. A baseline separation of the target analytes was achieved in less than 10min by using a BGE consisting of 35mM borate along with 15mM β-CD and 3mM l-alanine tert butyl ester lactate (l-AlaC4 Lac) IL as buffer additives at pH 9.5, a temperature of 25°C, and an applied voltage of 30kV. The application of the developed electrophoretic method to real samples enabled the identification and quantification of the main phenolic constituents of both ripe and unripe carob pulp extracts. The results revealed the predominance of gallic acid in both ripe (183.92μg/g carob pulp) and unripe (205.10μg/g carob pulp) carob pulp and highlighted the great influence of the ripening stage on carobs polyphenolic composition, with unripe pods being more enriched in polyphenols (total phenolics detected: 912.58 and 283.13μg/g unripe and ripe carob pulp).

Separation of Sucralose in Food Samples using Amines as Background Electrolyte Supported with DFT Calculations

Background: Sucralose is a high intensity artificial sweetener and chemically known as 1,6-dichloro-1,6-dideoxy-β-D-fructofuranosyl-4-chloro-4-deoxy-α-D-galactopyranoside. It is used as a sweetener and flavour enhancer in foods and beverages. Due to its high stability at wider temperatures and pH, it made its applicability in various food products throughout the world. As per Joint FAO/WHO Expert Group on Food Additives (JECFA) in 1990, the daily intake of sucralose is 0-15 mg/kg body weight. The literature reports suggest that sucralose has a possible health threat due to the presence of chlorine groups, thereby leading to several illnesses. The growing interest in the use of sucralose (SCL) in the foods makes it necessary in developing a fast, reliable, cost effective and reproducible analytical method to determine SCL in food samples. The detection of sucralose and other carbohydrates like fructose, glucose and sucrose is a challenging task owing to its: (i) unavailability of the charged functions and (ii) lack of absorption of strong chromophoric nature in the UV region. Therefore, separation of non-absorbing neutral molecules needs a careful procedure with suitable electrolyte systems. Methodology: An indirect UV detection capillary electrophoretic method is described for the separation of sucralose in different food samples. It was achieved by nucleophile substitution (SN2) in the presence of amine as background electrolytes. The morpholine buffer showed good buffering capacity in terms of migration time (< 8.0 min) and baseline stability when compared to other amine buffers (ethylamine, piperidine, triethylamine). The analytical applications of proposed method showed by recovery percentages of sucralose in real and spiked samples on intra and inter-day basis at optimum experimental conditions of 0.2 M buffer concentration and pH 12.0 at 230 nm UV detection. Results: The selection of BGE, UV detection wavelength, buffer concentration, buffer pH, cassette temperature and applied voltage was optimized to enhance the sensitivity and selectivity of the separation method. Recoveries obtained were ranging from 96.87 to 98.82% for real samples and 94.45 to 98.06% for spiked samples, respectively. Linearity was studied in the range of 2-10 mM, and showed a correlation coefficient of 0.9942. LOD and LOQ were found to be 0.3804 mg L-1 and 1.5215 mg L-1 with % RSD (n = 5) ± 1.27 and 1.19% with respect to migration time and peak area. Furthermore, to better understand the separation of sucralose with amine buffers, were investigated computationally using HOMO-LUMO calculations. The obtained results showed that the band gap decreases in the presence of amine moiety irrespective of its nature. Conclusion: In the study, a novel background electrolytic system was successfully applied to separate sucralose using indirect UV detector with capillary electrophoresis. The FTIR results confirmed that the interaction of sucralose with different amine buffers to better understand the separation chemistry behind sucralose and amine complexes. Moreover, computational results indicate that the direction of charge transfer from the amine functionality to the glucofuranosyl ring in each amine derivative of sucralose confirms the strong interaction between sucralose and amines, which led to the baseline separation of sucralose in different food samples.

Enantioseparation of solriamfetol and its major impurity phenylalaninol by capillary electrophoresis using sulfated gamma cyclodextrin.

R-solriamfetol is a recently approved drug used for the treatment of excessive sleepiness associated with narcolepsy and sleep apnea. Herein, a capillary electrophoretic method was developed, enabling the simultaneous analysis of the API and its S-enantiomer in addition to the enantiomers of its major impurity phenylalaninol. Twenty-nine different cyclodextrins (CDs), including native, neutral, and charged ones were screened as potential chiral selectors, and the best results were obtained with sulfated CDs. Randomly sulfated-β-CD exhibited outstanding enantioresolution, the peaks of phenylalaninol enantiomers inserted between the two peaks of solriamfetol enantiomers, while sulfated-γ-CD (S-γ-CD) showed remarkable resolution values in a much shorter analysis time with the optimal enantiomer migration order. Among the single isomer sulfated CD derivatives, substituent dependent enantiomer migration order reversal could also be observed in the case of heptakis(6-O-sulfo)-β-CD (HS-β-CD) or heptakis(2,3-O-dimethyl-6-O-sulfo)-β-CD (HDMS-β-CD) with R-,S-solriamfetol, and heptakis(2,3-O-diacetyl-6-O-sulfo)-β-CD (HDAS-β-CD) resulting S-,R-solriamfetol migration order. The sulfated-γ-CD system was chosen for method optimization applying orthogonal experimental design. The optimized method (45mM Tris-acetate buffer, pH 4.5, 4mM S-γ-CD, 21°C, +19.5kV) was capable for the baseline separation of solriamfetol and phenylalaninol enantiomers within 7min. The optimized method was validated according to the ICH guidelines and successfully applied for the analysis of pharmaceutical preparation (Sunosi® 75mg tablet), thus it may serve as a routine procedure for the laboratories of regulatory authorities as well as in Pharmacopoeias.

Capillary electrophoretic method for Staphylococcus aureus detection by using a novel antimicrobial peptide.

A novel peptide containing antimicrobial sequence and gelatinase cleavage sites was designed for Staphylococcus aureus detection. Since Staphylococcus aureus could secrete gelatinase, the fluorescein labeled peptide GKRWWKWWRRPLGVRGC could be recognized and cleaved. The obtained products were able to be analyzed by capillary electrophoresis with fluorescence detection. To explore the effect of Staphylococcus aureus concentration on enzyme digestion ability of peptide, Staphylococcus aureus with different concentrations were incubated with the peptide. Results indicated that capillary electrophoretic method was efficient for determining Staphylococcus aureus content. Compared with traditional approaches for Staphylococcus aureus detection, capillary electrophoresis possessed higher efficiency, enhanced sensitivity, and low sample consumption. Moreover, the proposed peptide also presented desirable antimicrobial activity. It suggested that the novel antimicrobial peptide used in this research opens a new path of detecting Staphylococcus aureus by capillary electrophoretic method.

Metformin residue analysis in water by MWCNTs-based solid-phase micromembrane tip extraction and capillary electrophoresis methods

Metformin is the largest drug produced globally in metric tons. It has been reported in many water treatment plants and water resources. The analysis of metformin at trace level is important before supplying water to the communities. The present article describes solid-phase micromembrane tip extraction and capillary electrophoretic methods for the analysis of metformin in water using multi-walled carbon nanotubes as a sorbent in the sample preparation method. The maximum extraction of metformin was achieved at 10.0 mg/L metformin, 25 shaking time, 0.5 g/L CNTs dose, 7.0 sorption pH, 30-min desorption time and 12 desorption pH. The migration time of metformin was 8.4 min with 2.0 × 10–4, 1.35 × 10–4 and 15,600 as electrophoretic mobility (cm2V−1 s−1), electroosmotic mobility (cm2V−1 s−1) and the number of theoretical plates. These solid-phase micromembrane tip extraction and capillary electrophoretic methods were highly applicable to monitor metformin in the wastewater. The reported methods are efficient, reproducible and useful for the estimation of metformin in water and may be exploited for the analysis of the metformin water resource.