Showing papers in "Chromatographia in 2020"
TL;DR: The aim of this article is to present a general overview of mass spectrometry applications in the field of PTM mapping and the analytical challenges of particular PTMs, primarily focusing on the most frequent modifications.
Abstract: Post-translational modifications controlling a large number of biological functions are key aspects of protein diversity. They have an important role controlling cellular processes and may be advantageously utilized. Qualitative and quantitative analyses of post-translational modifications are useful for biomarker research and an integral part of the characterization of protein biopharmaceuticals. Due to its sensitivity and widespread applicability, mass spectrometry has become the core technology of the analysis especially when combined with chromatographic and other separation techniques. The aim of this article is to present a general overview of mass spectrometry applications in the field of PTM mapping. We also present the analytical challenges of particular PTMs, primarily focusing on the most frequent modifications.
50 citations
TL;DR: The overall results depicted the reliability and robustness of both the AI-based models and justified the enhancement capability for ensemble techniques for both the two analytes.
Abstract: Reliable simulation of retention factor (k) is crucial in high-performance liquid chromatography (HPLC) method development. In this research, three different Artificial intelligence (AI) based models, namely the multi-layer perceptron (MLP), Support vector machine (SVM) and Hammerstein–Weiner (HW) models, were employed as well as three ensemble techniques, i.e., neural network ensemble (NNE), weighted average ensemble (WAE) and simple average ensemble (SAE) to predict k for HPLC method development. In this context, the pH and composition of the mobile phase (methanol) are used as the input variables with the corresponding Methyclothiazide (M) and Amiloride (A) as antihypertensive target analytes. The performance efficiency of the models was evaluated using mean square error (MSE), determination coefficient (R2), and correlation coefficient (R). The results obtained from the single models showed that MLP outperformed the other two models and increased the prediction accuracy up to 1% and 3% for the HW and SVM models, respectively, for the prediction of M. However, for the prediction of A, SVM outperformed the other two models and increased the prediction accuracy up to 7% and 6% for HW and MLP, respectively. In the ensemble technique, the results obtained for the prediction of both M and A demonstrated that NNE increased the performance accuracy by 14% of the single models. Also, NNE proved to be superior to the two linear ensembles and improved the prediction accuracy up to 14% and 2% for SAE and WAE, respectively, for the simulation of M with R2 = 0.9962 and 0.9949 for both calibration and verification, and up to 9% and 6% for A with R2 = 0.9606 and 0.9569 for both calibration and verification phases respectively. The overall results depicted the reliability and robustness of both the AI-based models and justified the enhancement capability for ensemble techniques for both the two analytes.
42 citations
TL;DR: In this article, the authors examine the advances that are enabling portable liquid chromatography (LC) and explore the evolution of portable instrumentation from its inception to the most recent advances, highlighting the trends in the field and discussing the necessary criteria for developing in-field solutions.
Abstract: There is a growing need for chemical analyses to be performed in the field, at the point of need. Tools and techniques often found in analytical chemistry laboratories are necessary in performing these analyses, yet have, historically, been unable to do so owing to their size, cost and complexity. Technical advances in miniaturisation and liquid chromatography are enabling the translation of these techniques out of the laboratory, and into the field. Here we examine the advances that are enabling portable liquid chromatography (LC). We explore the evolution of portable instrumentation from its inception to the most recent advances, highlighting the trends in the field and discussing the necessary criteria for developing in-field solutions. While instrumentation is becoming more capable it has yet to find adoption outside of research.
35 citations
TL;DR: In this article, an HPLC method with fluorescence detection was developed and validated for histamine level determination in fish and fish products, which is important for human safety, fish quality and food industry.
Abstract: Histamine level determination in fish and fish products is important for human safety, fish quality and food industry. For this reason, a rapid, robust, and precise method is needed. To achieve this objective, an HPLC method with fluorescence detection was developed and validated. Histamine in fish samples was efficiently extracted with perchloric acid, and purified with ion-exchange solid-phase extraction cartridge. A pre-column derivatization was adopted with ortho-phthalaldehyde (OPA) in the presence of the reducing agent 2-mercaptoethanol, and the stability of the histamine-OPA derivatives was achieved with the acidification of the reaction medium. In terms of validation, besides the excellent linear correlations, satisfactory recoveries at all spiking levels ranging between 0 and 200 mg kg−1 were attained, with limit of detection calculated at 1.8 mg kg−1, whereas limit of quantification determined at 5 mg kg−1. The proposed method was successfully used in the analysis of reference materials and proficiency tests, and was found to be suitable, accurate, and rapid for detection and quantification of histamine in various fish samples.
22 citations
TL;DR: A review of publications pertaining to the application of different types of microextraction techniques in the analysis of biological samples along with their different aspects and a discussion of their future can be found in this article.
Abstract: Sample preparation is a critical step in the separation of target analytes from complex matrices, which can influence the reliability and accuracy of the resulting analysis. Recent trends in sample preparation techniques are directed toward the automation and online coupling of sample preparation units, miniaturization, high efficiency, low costs, and reducing or eliminating solvent consumption. Microextraction techniques (METs) have all these advantages over conventional extraction methods. Thus, the application of METs in the analysis of different analytes from biological samples has increased significantly in recent years. Over time, many review articles have been written, which focus on the advantages, applications, and advances of these techniques for the analysis of various compounds in biological matrices. This paper presents a review of publications pertaining to the application of different types of METs in the analysis of biological samples along with their different aspects and a discussion of their future.
20 citations
TL;DR: In this paper, an optimized capillary zone electrophoresis (CZE) separation of the DNS-BA derivates (derivates of cadaverine, histamine, putrescine, tryptamine, and tyramine) was performed using benzylamine as an internal standard, a potential of 18 kV, a temperature of 23 kC, a running buffer consisting of phosphoric acid, 120mmol L−1, pH 2.5, and an hydrodynamic injection at 25 mBar for 6 s.
Abstract: Biogenic amines (BAs) are important compounds that can be used in the quality control of food and beverages. BA analysis is a challenging task that can be made easier by applying a derivatizing agent like dansyl chloride (DNS). The optimized capillary zone electrophoresis (CZE) separation of the DNS-BA derivates (derivates of cadaverine, histamine, putrescine, tryptamine, and tyramine) was performed using benzylamine as an internal standard, a potential of 18 kV, a temperature of 23 °C, a running buffer consisting of phosphoric acid, 120 mmol L−1, pH 2.5, and an hydrodynamic injection at 25 mBar for 6 s. All calibration curves had r2 higher than 0.99, and limits of detection (LODs) ranged from 7 to 50 µg L−1. The developed methodology was tested in cheese and yogurt samples. DNS showed to be an alternative derivatization reagent not only because it produced UV-detectable derivates (214 nm), but also because of its stability, aqueous solubility, high selectivity and sensitivity, reduced impurities, and simple preparation steps.
18 citations
TL;DR: In this article, the authors applied the quality by design strategy for the simultaneous chromatographic quantification of a binary mixture of bromhexine HCl and its pharmacologically active metabolite ambroxol HCl in dosage forms as well as in human plasma.
Abstract: The quality by design strategy was applied for the simultaneous chromatographic quantification of a binary mixture of bromhexine HCl and its pharmacologically active metabolite ambroxol HCl in dosage forms as well as in human plasma. In this study, five independent parameters were screened by fractional factorial design to specify the critical ones. The optimal conditions were determined by a response surface methodology using a central composite design. Response surface methodology enabled the best separation in minimal run time, as well as, prediction of separation and retention parameters with minimum error. Separation and quantitation were carried out on BDS Hypersil C8 (250 × 4.6 mm, 5 μm) RP-column at 1.1 mL min−1 flow rate, 25 mM of KH2PO4 (pH 3.5) in aqueous mobile phase, 65% MeOH, 210 nm wavelength of detection and 10 µL injection volume. After optimization of the chromatographic parameters, validation of the method was achieved according to ICH guidelines. Linearity ranged from 0.195 to 100 µg mL−1 ambroxol HCl, and 0.391–100 µg mL−1 bromhexine HCl, with R2 values of 0.9998 and 0.9999 and limits of detection of 0.098 and 0.195 µg mL−1, respectively. Recovery results ranged from 98.06 to 100.18 and 97.88 to 100.68 for bromhexine HCl and ambroxol HCl, respectively, with RSD less than 1.80.
17 citations
TL;DR: In this article, a novel solid-phase microextraction technology, in which the features of heating of sample, cooling of sorbent, and extraction under vacuum condition have been merged.
Abstract: This research introduces a novel solid-phase microextraction technology, in which the features of heating of sample, cooling of sorbent, and extraction under vacuum condition have been merged. Heating-, cooling- and vacuum-assisted solid-phase microextraction (HCV-SPME) method was developed as an efficient solution for the direct extraction of volatile and semi-volatiles species in complex solid samples. HCV-SPME was coupled with an in-needle capillary adsorption trap (HCV-INCAT) and applied to the direct extraction of polycyclic aromatic hydrocarbons (PAHs) within soil samples. It consisted of polythiophene/carboxylic acid modified multi-walled carbon nanotube nanocomposite, which was synthesized and wall-coated within a platinized stainless-steel needle via electropolymerization. The influential experimental variables (desorption conditions, sample temperature, adsorption temperature, sampling flow rate, and vacuum level) on the extraction efficiency were optimized. The developed HCV-INCAT technique was used in conjunction with GC-FID and applied for the extraction and determination of PAHs in contaminated soil samples, closely matching with those obtained using a validated ultrasonic-assisted solvent extraction procedure. Under the optimal conditions, linear dynamic ranges, limits of detection, and relative standard deviations were obtained 0.007–5 µg g−1, 8–20 pg g−1, and 7.1–12.1%, respectively, for direct extraction of naphthalene, fluorene, phenanthrene, fluoranthene, and pyrene from solid samples.
16 citations
TL;DR: In this article, a quality by design-based stability indicating HPLC method has been developed for hydroxychloroquine sulfate impurities in pharmaceutical solid oral dosage forms, which allows the assessment of different analytical parameters and their effects with minimum number of experiments.
Abstract: A quality by design-based stability indicating HPLC method has been developed for hydroxychloroquine sulfate impurities. The optimized HPLC method can detect and quantify the hydroxychloroquine sulfate and related organic impurities in pharmaceutical solid oral dosage forms. Nowadays, for the quantification of impurities in drug products demands more comprehensive way of analytical method development. The quality by design approach allows the assessment of different analytical parameters and their effects with minimum number of experiments. A highly sensitive and stability indicating RP-HPLC method was developed and evaluated the risk assessment prior to method validation. The chromatographic separation was achieved with X-terra phenyl column (250 × 4.6 mm, 5 µm) using phosphate buffer (0.3 M and pH 2.5). The gradient method flow rate was 1.5 mL min−1 and UV detection was made at 220 nm. The calibration curve of hydroxychloroquine sulfate and related impurities were linear from LOQ to 150% and correlation coefficient was found more than 0.999. The precision and intermediate precision % RSD values were found less than 2.0. In all forced degradation conditions, the purity angle of HCQ was found less than purity threshold. The optimized method found to be specific, accurate, rugged, and robust for determination of hydroxychloroquine sulfate impurities in the solid oral dosage forms. Finally, the method was applied successfully in quality control lab for stability analysis.
14 citations
TL;DR: In this paper, the authors reported the synthesis of graphene oxide and polyvinyl poly pyrrolidone composite and its application in the extraction of aflatoxins in food samples.
Abstract: The present investigation reports the synthesis of graphene oxide–polyvinyl poly pyrrolidone composite and its application in the extraction of aflatoxins in food samples. This composite was successfully synthesized and characterized with analytical instruments such as UV–Vis, FITR, XRD, and SEM techniques. The extraction was carried out by reinforced hollow fiber liquid-phase microextraction coupled with high-performance liquid chromatography (HPLC). Various parameters that affect the productivity of the present technique were exhaustively explored, and the quantifications were carried out under the optimized states. The limits of detection (LODs) were found to be 0.33, 0.10, 0.37, and 0.10 ng g−1, and limits of quantification (LOQs) were 1.10, 0.33, 1.24, and 0.33 ng g−1, respectively, for aflatoxins B1, B2, G1, and G2. The accuracy of the present method was determined based on the relative recovery (RR%) of the aflatoxins and the RR% of aflatoxins B1, B2, G1, and G2 which were found to be quite good (between 60.20 and 108.20 for 1 ng g−1 and between 62.02 and 95.39 for 5 ng g−1) in food samples. Applicability of the sorbent for the separation and quantification of the above-mentioned aflatoxins from food samples were examined. The developed method is straightforward, reliable, and effective, and has been successfully applied in determination of aflatoxins from food samples.
14 citations
TL;DR: The most abundant amino acids in proso millet grains are glutamic acid/glutamine (2.13´±´0.34´g per 100´g), alanine (1.06´±`0.18´g) and leucine(1.36´±''0.24´g ) as mentioned in this paper.
Abstract: Amino acids are valuable nutrients, responsible for a variety of tasks in the human body. A favourable amino acid profile in gluten-free crops, such as millet, can thus be beneficial for human health, which is why 35 proso millet (Panicum miliaceum L.) samples, comprising 23 whole and 12 dehulled, were investigated regarding their amino acid profiles and compositions using acidic hydrolysis and ion-exchange chromatography with ninhydrin derivatization and subsequent detection with photometry. Results for amino acid compositions were compared with gluten-containing wheat and other gluten-free cereals. Furthermore, gained values were put in contrast to estimated essential amino acid requirements for adult humans. The study was able to show that cultivars of proso millet differ and that dehulling does not significantly influence the amino acid compositions. Furthermore, the results display that Panicum miliaceum L. holds more essential amino acids than other gluten-free grains and exhibits high amounts of leucine and alanine. The methionine content differs greatly between samples, which means that choosing certain cultivars is important to ensure a high content. The most abundant amino acids in proso millet grains are glutamic acid/glutamine (2.13 ± 0.34 g per 100 g), alanine (1.06 ± 0.18 g per 100 g) and leucine (1.36 ± 0.24 g per 100 g).
TL;DR: In this article, a critical review of the use of ionic liquids in the microextraction of pesticide residues in fruits and vegetables is provided, which includes an assessment of the advantages and limitations of current applications of ionicle liquids in micro-extraction techniques.
Abstract: The objective of this work is to provide a critical review of the use of ionic liquids in the microextraction of pesticide residues in fruits and vegetables. It includes an assessment of the advantages and limitations of current applications of ionic liquids in microextraction techniques. The review also aims to illustrate the impact of ionic liquids on the development of novel sorbent materials for analytical applications. The unique physicochemical properties of ionic liquids make them ideal sorbents in separation techniques. Their number of applications in analytical separation has increased considerably over the past 5 years. Therefore, this review focuses on the synthesis, purification, functionalization, and application of ionic liquids for pesticide residue analysis in fruits and vegetables with different sample preparation procedures, covering articles published in the literature since their first application in 2009.
TL;DR: In this paper, a simple, rapid, and accurate stability-indicating reverse phase HPLC-DAD method was developed and validated for the simultaneous determination of empagliflozin, dapaglifllozin and canaglifloczin (Gliflozins).
Abstract: A simple, rapid, and accurate stability-indicating reverse phase HPLC–DAD method was developed and validated for the simultaneous determination of empagliflozin, dapagliflozin, and canagliflozin (Gliflozins). Optimum chromatographic separations among gliflozins in the presence of matrices and degradation products have been achieved within 7 min by using Hypercil™ C18 column (25 × 4.6 mm, 5 μm) with acetonitrile and 0.1% formic acid buffer, pH 3.7 (60:40 v/v) as the mobile phase at a flow rate of 1 mL min−1. The proposed method was performed at 230 nm for empagliflozin and dapagliflozin while detection of canagliflozin was carried out at 290 nm. Analytical performance of the method was thoroughly validated in accordance with the ICH guidelines with respect to system suitability, linearity, accuracy, precision, specificity, robustness, detection and quantification limits. Regression analysis showed good correlations with regard to R2 ≥ 0.997 over the concentration range of 4–160 µg mL−1 for gliflozins. The LOD was found to be 0.07 µg mL−1, 0.12 µg mL−1 and 0.29 µg mL−1 for empagliflozin, dapagliflozin and canagliflozin, respectively. Method development was established keeping in view the structure of drugs, their pKa values, ionizability of drugs, pH values of buffer system and buffer capacity. Peak purities of gliflozins in stress tests are less than 1.5, which further confirms no co-elution of degradation products. The proposed method is suitable for routine quality control analysis of gliflozins and to carry out stability studies.
TL;DR: In this paper, carbon nanodots (CNDs) were successfully anchored on magnetite (Fe3O4) under magnetic stirring and the nanocomposite prepared was assessed as a new adsorbent for ultrasonic-assisted magnetic solid-phase dispersive extraction of chlorpyrifos (CPF) and triclosan (TCS) in water samples.
Abstract: In the present study, carbon nanodots (CNDs) were successfully anchored on magnetite (Fe3O4) under magnetic stirring and the nanocomposite prepared was assessed as a new adsorbent for ultrasonic-assisted magnetic solid-phase dispersive extraction of chlorpyrifos (CPF) and triclosan (TCS) in water samples. Detection was achieved using ultrahigh performance liquid chromatography–tandem mass spectrometry (LC–MS/MS). The prepared magnetic CNDs were characterised by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared and X-ray diffraction. The investigation and optimisation of the main experimental variables having an influence on the analytical response were performed using a multivariate approach. The factors studied were sample pH, mass of adsorbent and extraction time. The selection of desorption solvent and desorption time were examined and optimised univariately. By appropriating the optimum experimental conditions, the developed method was validated for accuracy using real environmental water samples. The average percentage recoveries obtained using influent and effluent spiked wastewater samples ranged between 76–108% and 79–96% for CPF and TCS, respectively. A good linearity (R2 > 0.995) was established ranging between 5 and 100 µg L−1. The limit of detection and limit of quantification were in the range of 0.024–0.081 µg L−1 and 0.057–0.192 µg L−1, respectively. The repeatability and reproducibility expressed as % relative standard deviation were less than 4.7%. The developed method exhibited good method performance, is rapid, simple, inexpensive and environmentally friendly.
TL;DR: In this article, a clean-up approach named Bond Elut Enhanced Matrix Removal Lipid (EMR-Lipid) was developed for the simultaneous determination of 325 pesticides in the chicken egg by UHPLC and GC-MS/MS.
Abstract: Eggs are one of the most common foods in the world, and their safety is a major concern for the public. We aimed to develop a novel clean-up approach named Bond Elut Enhanced Matrix Removal-Lipid (EMR-Lipid) for the simultaneous determination of 325 pesticides in the chicken egg by UHPLC–MS/MS and GC–MS/MS. The initial step of extraction was adopted by acetonitrile with 5% formic acid and subsequent adoption of EMR-Lipid d-SPE for further clean-up. Compared with the traditional C18 procedure, EMR-Lipid clean-up achieved a superior degreasing effect. The recoveries of at least 85% of pesticides were in the range of 60–120% at three fortified levels and the relative standard deviation of nearly 96% of analytes were within the limits of criteria. Improved linearity was evaluated using a matrix-matched calibration at eight concentrations in the range 0.1–40 µg/kg; the correlation coefficients of 309 analytes were exceeding 0.99. The new method offered quick, reliable and consistent detection and quantification of 325 pesticide residues, thereby demonstrating promising future for sample testing.
TL;DR: In this paper, a simple and isocratic HPLC-UV method for enantioseparation of mainly cathinone and pyrovalerone derivatives as well as selected representatives of amphetamines, ketamines, benzofuries, phenidines, phenidates, morpholines and thiophenes was presented.
Abstract: The misuse of so called novel psychoactive substances is still a challenging problem worldwide. A special attribute of a lot of these compounds is a chiral centre enabling two possible enantiomers probably related to different pharmacological and toxicological properties. The goal of the present study was to present a simple and isocratic HPLC–UV method for enantioseparation of mainly cathinone and pyrovalerone derivatives as well as selected representatives of amphetamines, ketamines, benzofuries, phenidines, phenidates, morpholines and thiophenes. A Waters Acquity UPC2® Trefoil™ CEL1 2.5 µm, 3.0 × 150 mm column served as chiral stationary phase by means of cellulose tris-(3,5-dimethylphenylcarbamate) as chiral selector. Mobile phases consisted either of n-hexane/n-butanol/diethylamine (100:0.3:0.2) or n-hexane/diethylamine (100:0.2). The method was found to be applicable for rapid simultaneous chiral separations of cathinone derivatives, to determine enantiomeric elution orders, to detect positional isomers and to identify real-life samples. Also, a repeatability study was performed successfully. 78 out of 95 compounds were separated in their enantiomers successfully, 51 of them within 6 min. It was shown that all NPS bought from online vendors or seized by police were traded as racemic mixtures.
TL;DR: In this article, a liquid chromatography-triple quadrupole tandem mass spectrometry (LCQqQ-MS/MS) method was developed for analysis of 41 representative antibiotics and their two metabolites in human urine samples.
Abstract: An accurate assay suitable for human biomonitoring of multiclass antibiotics preferred for veterinary use is currently lacking. In this study, we developed a liquid chromatography-triple quadrupole tandem mass spectrometry (LC–QqQ–MS/MS) method for analysis of 41 representative antibiotics (eight categories) and their two metabolites in human urine samples. Additionally, along with matrix-matched calibration and solid-phase extraction (SPE), use of 36 stable isotopically labeled internal standards (SIL-ISs) compensated for matrix effects and helped in the accuracy of quantitation. The absolute matrix effects (MEs), the linearity of limits of detection (LODs) and limits of quantitation (LOQs), stability, accuracy and precision of this method were validated. The validation parameters obtained for the targeted compounds are as follows: MEs (68.0–129.2%), LODs (0.016–1.481 ng mL−1), LOQs (0.050–4.812 ng mL−1), and higher recoveries (80.3–112.5%) except cyadox and cefaclor. The regression coefficients (r2) of targeted compounds at a concentration range of 0.05–100 ng mL−1 ranged from 0.9958 to 0.9998. The intra- and inter-precisions were obtained with a relative standard deviation (RSD%) < 13%. The method was successfully applied to analyze 302 urine samples of pregnant women from the China-Anhui Birth Cohort (C-ABC), and 36 of the selected antibiotics and two metabolites were detected. The total detection frequencies were 52.6% (fluoroquinolones), 40.4% (tetracyclines), 33.1% (sulfonamides), 16.9% (chloramphenicols), 11.6% (macrolides), 10.9% (β-lactams), 2.3% (lincosamides), and 0.3% (quinoxalines), respectively. The developed method has been successfully employed to obtain reliable quantitative results in the urine of pregnant women.
TL;DR: In this article, a high-performance liquid chromatographic method was developed for the separation and determination of 13 vitamin B compounds, including thiamin, riboflavin, rhodiola 5′-monophosphate, pyridoxine, hydroxocobalamin, cyanocobalamina, adenosylcobalamin and niacinamide.
Abstract: A high-performance liquid chromatographic method was developed for the separation and determination of 13 vitamin B compounds, including thiamin, riboflavin, riboflavin 5′-monophosphate, pyridoxine, hydroxocobalamin, cyanocobalamin, adenosylcobalamin, methylcobalamin, niacin, niacinamide, pantothenic acid, folic acid, and biotin. The method consisted of an ODS column, a gradient elution using pH 3.0 phosphate buffer–acetonitrile, ion-pairing reagent as mobile phase at 1.0 mL min−1, and UV detection at 210 nm. As a result, the 13 vitamin B compounds were separated in 60 min, and the specificity, linearity, range, limit of detection, limit of quantitation, intra- and inter-day precision, and recovery were satisfactory. The limit of detections ranged from 0.03 to 0.41 µg mL−1. Intra- and inter-day precision of peak area, expressed as RSD, were 0.542–5.144% and 0.216–6.367%, respectively. The method was used to evaluate vitamin B compounds in energy drinks and multivitamin pills. In case of energy drink analysis, the method identified and evaluated not only vitamin B compounds but also major ingredients, such as caffeine, vanillin, and benzoic acid. The vitamin B compounds in energy drinks and multivitamin pills were also quantitated and compared with values listed on each product label. Each quantitative value was close to the label values, suggesting high quantitative ability of the developed method.
TL;DR: In this article, an ultrasound assisted deep eutectic solvent-based liquid phase microextraction (UA-DES-LPME) was established for the extraction of carbamazepine (CBZ) from human plasma samples.
Abstract: An ultrasound-assisted deep eutectic solvent-based liquid-phase microextraction (UA-DES-LPME) was established, for the first time, for the extraction of carbamazepine (CBZ) from human plasma samples. The extract was determined by HPLC-ultraviolet detection (HPLC–UV). A deep eutectic solvent (DES) was readily synthesized by mixing choline chloride and phenol (ChCl:Ph) in the mole ratio of 1:2 in ambient temperature and used without any further purification. In the present method, THF was used as an emulsifier agent. Some parameters, including the DES components mole ratio, kind of emulsifier agent, and salt addition effect, were optimized by a one-at-a-time approach. Central composite design (CCD) was used to optimize the rest of the effective parameters, including DES volume, pH, ultrasonication time, and THF volume. The optimum conditions were found to be: 11.78 pH, 314 µL DES volume, 523 µL THF volume, and 9.0 min ultrasonication time. The performance of the method was evaluated under optimum conditions, and the method exhibited good linearity over a concentration range of 10–1500 ng mL−1, low limit of detection and quantitation, good precision, and high extraction recovery. Finally, the applicability of the method was assessed by analysis of the spiked plasma samples, and the results have shown high relative recoveries with good precision.
TL;DR: In this article, a sensitive and simple analytical method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been established for determination of 25 herbicides in soil as well as fresh and flue-cured tobacco leaf.
Abstract: In the cultivation of tobacco, crop rotation patterns, such as tobacco/rice or tobacco/corn, are widely used. However, the use of herbicides in the rice or corn phase can lead to their being taken in during the tobacco phase by inner conduction action. In the present study, to monitor the use of herbicides in tobacco, a sensitive and simple analytical method coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS) has been established for determination of 25 herbicides in soil as well as fresh and flue-cured tobacco leaf. The herbicides analyzed include six aryloxy phenoxy propionate herbicides (APPs) and 19 sulfonylureas herbicides (SUs). The samples were extracted using acetonitrile and purified using C18 sorbent before analysis. Optimum separation of the analytes was achieved using an Agilent Eclipse XDB-C18 column at 40 °C and gradient elution with acetonitrile and 0.1% aqueous formic acid as the mobile phase at a flow rate of 0.8 mL min−1. The limits of quantification and detection are in the ranges 0.08–1.00 mg kg−1 and 0.024–0.30 mg kg−1, respectively, and matrix effects in the range − 70 to 50% were achieved. The recovery rates obtained from spiked soil and tobacco leaf samples ranged from 72.32 to 116.83% with intra-day and inter-day relative standard deviations of 0.44–11.55%. In addition, the method developed was applied to the determination of herbicides residues in actual soil and tobacco samples, revealing that the proposed method can detect trace amounts of APPs and SUs in soil as well as in fresh and flue-cured tobacco leaf.
TL;DR: In this paper, a method for the simultaneous determination of glyphosate and aminomethylphosphonic acid (AMPA) in urine was developed using a "dilute-and-shoot" sample preparation.
Abstract: A method for the simultaneous determination of glyphosate and aminomethylphosphonic acid (AMPA) in urine was developed using a “dilute-and-shoot” sample preparation. A 1:1 dilution of urine sample in 15 mmol L−1 heptafluorobutyric acid (HFBA) was prepared prior to being injected into the LC–MS/MS system. The chromatographic separation was achieved by a Gemini C6-Phenyl analytical column, with the gradient elution of 15 mmol L−1 HFBA in water and acetonitrile. The limits of detection and quantitation of both compounds were 2.5 ng mL−1 and 5 ng mL−1, respectively. The sample preparation time was achieved in 2 min using only 0.1 mL of urine sample. The validated method was successfully applied to glyphosate and AMPA determination in farmer urine samples.
TL;DR: In this article, a quality-by-design approach for the simultaneous determination of dextrodropropizine and the achiral precursor 1-phenylpiperazine in levodropropizer was developed.
Abstract: Based on a quality by design approach, a capillary electrophoresis method for the simultaneous determination of dextrodropropizine and the achiral precursor 1-phenylpiperazine in levodropropizine was developed. The analytical target profile was defined as a method allowing the simultaneous determination below the 0.5% level within a maximum analysis time of 20 min with an acceptable precision and accuracy. Based on scouting experiments, sulfated β-cyclodextrin in a 25 mM potassium phosphate buffer, pH 7.0, was selected. Subsequently, cyclodextrin concentration, propan-2-ol concentration, capillary temperature and applied voltage were identified as critical process parameters using a full factorial design followed by a central composite face-centered design for the final optimization of cyclodextrin concentration and temperature. The design space was obtained by Monte Carlo simulations. The final method comprised a 40/50.2 cm effective/total length, 75 µm inner diameter fused-silica-capillary, 25 mM potassium phosphate buffer, pH 7.0, containing 23.5 mg mL−1 sulfated β-cyclodextrin and 10% (v/v) propan-2-ol as background electrolyte, 16.3 °C capillary temperature and an applied voltage of 16.5 kV. The robustness was assessed using a Plackett–Burman design followed by method validation. Finally, the method was applied to the analysis levodropropizine reference substance of the European Pharmacopoeia and a liquid dosage form.
TL;DR: A composite material featuring a zirconium-based metal-organic framework and graphene oxide (Zr-MOF@GO) was synthesized by a hydrothermal method and bonded to a stainless steel wire with an inorganic binder as a solid-phase microextraction (SPME) fiber for the derivatization-free extraction and analysis of nonsteroidal anti-inflammatory drugs (NSAIDs) coupled with gas chromatography (GC) as mentioned in this paper.
Abstract: A composite material featuring a zirconium-based metal–organic framework and graphene oxide (Zr-MOF@GO) was synthesized by a hydrothermal method and bonded to a stainless steel wire with an inorganic binder as a solid-phase microextraction (SPME) fiber for the derivatization-free extraction and analysis of nonsteroidal anti-inflammatory drugs (NSAIDs) coupled with gas chromatography (GC). The force between the Zr-MOF@GO and NSAIDs includes coordination action, H-bonding, and π–πconjugation effect, which results in the better extraction performance than a commercial polyamide fiber. The developed method achieved low detection limits (0.001–0.030 µg L−1, S/N = 3) and wide linear range (0.01–500 µg L−1) with good linearity (R ≥ 0.9970). The fiber coating had a high scratch resistance, which could effectively prevent coating wear and failure due to the friction between the fiber and the casing. Combined with the high thermal and chemical stability, the loss-free service life of the coating reached at least 240 extractions. Particularly, the derivatization-free extraction technique can greatly reduce the extraction time and use of organic solvents, thus maximizing the SPME technology advantages. It is evident that the analysis method is simple, environmentally friendly, and fast for detecting NSAIDs in water with high efficiency and long service life.
TL;DR: In this article, Dasatinib along with its six known organic impurities were separated using the reversed-phase high performance liquid chromatography with C18 column and mobile phases consisting of gradient mixture of 20mM potassium phosphate buffer at pH 6.0 with 1-octanesulphonic acid sodium salt (0.1%, w/v), acetonitrile and ultrapure water.
Abstract: Dasatinib is a protein kinase inhibitor used for the treatment of chronic myelogenous leukemia and acute lymphoblastic leukemia. Dasatinib along with its six known organic impurities were separated using the reversed-phase high performance liquid chromatography with C18 column and mobile phases consisting of gradient mixture of 20 mM potassium phosphate buffer at pH 6.0 with 1-octanesulphonic acid sodium salt (0.1%, w/v), acetonitrile and ultrapure water. This method was successfully tested with liquid chromatography coupled mass-spectrometry to elucidate the chemical structure of newly formed degradation product of Dasatinib which was identified by comparing its retention time and mass-spectra with literature data. Stability-indicating characteristics of developed HPLC method was assessed using stress testing [5 N HCl at 90 °C/1 h, 5 N NaOH at 90 °C/1 h, H2O at 90 °C/1 h, 30% H2O2 (w/w) at 25 °C ± 5 °C/1 h, dry heat at 105 °C/24 h and UV (200 W h m−2) and fluorescent light (1.2 million lux-h)] and was validated as per ICH Q2(R1). For Dasatinib and its six impurities, the quantification limits, linearity and recoveries were found in range of 0.19–0.21 μg/mL, 0.2–3.0 μg mL−1 (R2 > 0.995) and 85.5–107.0%, respectively. The developed HPLC method will also suffice the suitability for impurity profiling and assay of Dasatinib in bulk drugs and pharmaceutical formulations.
TL;DR: In this article, the authors combined quality by design principles and green analytical chemistry leads to development of green micellar HPLC method for analysis of atorvastatin calcium and amlodipine besylate in binary mixtures and in their tablet dosage forms within 8min.
Abstract: The combined implementation of quality by design principles and green analytical chemistry leads to development of green micellar HPLC method for analysis of atorvastatin calcium and amlodipine besylate in binary mixtures and in their tablet dosage forms within 8 min. A two-level fractional factorial design was implemented for screening of different method parameters affecting chromatographic responses. Box–Behnken design was then used to study and optimize the most critical parameters. The optimum chromatographic conditions obtained from Box–Behnken design involved the use of a mixture of 0.17 M sodium dodecyl sulfate solution adjusted to pH 2.9 and 10%v/v n-butanol as mobile phase at a flow rate of 1.5 mL min−1 and column temperature kept at 45 oC. The stationary phase was X-Bridge™ (150 mm × 4.6 mm, 5 μm) column. The fluorescence detection was programmed at 276/378 nm (excitation/ emission) for the first 5 mins for atorvastatin then switched to 366/442 nm (excitation/emission) for amlodipine. A linear response was obtained over the ranges of 0.2–25 μg mL−1 for both drugs. The proposed method was validated and successfully implemented for the simultaneous determination of cited drugs in their different tablet dosage forms. The method was additionally applied to content uniformity testing according to the official guidelines. The application of quality by design principles and green analytical chemistry results in development of robust green method with less trial and error experiments.
TL;DR: The use of high performance thin-layer chromatography (HPTLC) in combination with high resolution time of flight mass spectrometry (MS) for the detection, identification and imaging of ecdysteroids present in a number of plant extracts obtained from members of the Silene family is demonstrated.
Abstract: The use of high performance thin-layer chromatography (HPTLC) in combination with high resolution time of flight mass spectrometry (MS) for the detection, identification and imaging (HPTLC/MSI) of ecdysteroids (insect moulting hormones) present in a number of plant extracts obtained from members of the Silene family is demonstrated. DESI is shown to be a convenient method for the recovery of these polar polyhydroxylated steroids from the silica gel of the HPTLC plate for subsequent MS detection and imaging. The incorporation of an ion mobility separation (IMS) to the system to give HPTLC/IMS/MS provided additional drift time data which enabled more confident identification. Using HPTLC/DESI/IMS/MS, a range of ecdysteroids were detected and characterized in extracts of S. otitis, S nutans, S. maritime, S. viridiflora and S. fimbriata.
TL;DR: A polyacrylonitrile (PAN) coating was fabricated by electrospinning technique for using as a new extraction phase in mechanical stir bar sorptive extraction (MSBSE) as discussed by the authors.
Abstract: A polyacrylonitrile (PAN) coating was fabricated by electrospinning technique for using as a new extraction phase in mechanical stir bar sorptive extraction (MSBSE). The setup coupled with gas chromatography (GC) was proposed and applied for the extraction and determination of some low molecular weight polycyclic aromatic hydrocarbons (PAHs) in water samples. The effective parameters on the extraction process were optimized by the response surface methodology (RSM) based on the central composite design (CCD). Under the optimum conditions, the limits of detection (LOD) and limits of qualification (LOQ) were 0.008–0.4 ng mL−1 and 0.02–1.3 ng mL−1, respectively. The relative standard deviations (RSDs) for the analytes, including acenaphthene (Ace), anthracene (Ant), naphthalene (Nap) and phenanthrene (Phe), was less than 12.7%. The relative recoveries (RRs) were above 94%. The extraction of the analytes by the MSBSE coated with PAN consumed about 256 kWh m−3 of electric energy. The coating can be used 200 times without significant changes in its performance because of hydrophobicity and the high mechanical strength of PAN. The proposed approach to improve SBSE for extracting PAHs from water samples is cost-effective and time-efficient because the introduced coating can be fabricated in a short time and by inexpensive raw materials.
TL;DR: A new consumable-free three-dimensional comprehensive gas Chromatography (GC 3 -FID) was designed with modulators already known to comprehensive two-dimensional gas chromatography users to showcase the opportunity of implementing GC 3 systems.
Abstract: A new consumable-free three-dimensional comprehensive gas chromatography (GC3-FID) was designed with modulators already known to comprehensive two-dimensional gas chromatography (GC × GC) users to showcase the opportunity of implementing GC3 systems. A hybrid interface composed of a thermal desorption modulator and a fast forward-flush differential flow modulator was used with modulation periods of 6 s and 300 ms, respectively. The determination of allergens in perfumes associated with chemometric tools, namely, parallel factor analysis (PARAFAC) was accomplished to demonstrate the validity of the proposed system. Evaluated allergens included already regulated ones in Brazil and Europe, such as geraniol and menthol, as well as potential allergens recommended in a 2011 opinion reported by the European Scientific Committee on Consumer Safety. Limits of detection were found to be suitable for current regulations, under 0.001% or 10 µL L−1 for leave-on products. Considerations on the required acquisition rates, the limitations imposed by current modulator technology, the modulation periods used, and how they affect all three dimensions are thoroughly discussed. A GC3 coupled with mass spectrometry (GC3-MS) approach is also covered, as well as a comparison of the signal resolution/deconvolution with the increase of data dimensionality. Lastly, the union of GC3 and chemometric tools allowed for a solution that may be used for both qualitative and quantitative analyses.
TL;DR: This work presents an attempt to facilitate the choice between capillary electrophoresis and high-performance liquid chromatography on the basis of the RGB model, offering a transparent and pictorial way to compare individual parameters as well as the overall analytical potential of each tool.
Abstract: The choice between capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) is not easy and depends on many factors. An attempt to facilitate this choice is this work, in which both techniques have been confronted on the basis of the RGB model, offering a transparent and pictorial way to compare individual parameters as well as the overall analytical potential of each tool.
To ensure the universal nature of the comparison, a simple in composition and chemically diverse model sample was used, accompanied by the data processing method reducing the potential impact of analyte selection. Moreover, permanent coating of the inner surface of the capillary and addition of a surfactant to the separation buffer were considered as the additional factors that may affect the assessment of the CE technique. The presented analysis can be valuable in any discussions about the intrinsic advantages and disadvantages of CE and HPLC, and divagations on how they affect the overall potential and usability of each. We also provide access to the Excel worksheets used for the assessment, which can be easily modified to reevaluate the methods with a different selection of variables, and analyze other possible scenarios.
TL;DR: The presented study laid an evidence for a two-way pharmacological synergism with the combined therapy of LOS and ROS via increased hepatic influx of ROS and peak-plasma concentration of EXP3174, the LOS more potent metabolite.
Abstract: The combined therapy benefits of losartan and rosuvastatin, within the vascular injury, have been well characterized. Nonetheless, the pharmacokinetic interactions between such therapeutic agents have not been yet figured out, making the need for a sensitive analytical technique to be of great significance. In view of this, a highly selective, sensitive, and well-validated liquid chromatography–tandem mass spectrometric technique has been developed for the simultaneous estimation of losartan (LOS) and rosuvastatin (ROS) within the rat plasma using simvastatin as an internal standard. The proposed technique adopted a simple plasma protein preparation by acetonitrile for the extraction and purification of the drug-plasma samples obtained from the rat animal models. A separation process on the Agilent™ Eclipse-Plus® (C18, 0.46 × 15 cm, 3.5 μm) columns was conducted using gradient mobile phase system comprising of water/0.1%w/v formic acid and acetonitrile at 0.9 mL min−1 flow rate. Precursor quantification into production was performed using the multiple reaction monitoring within the positive-ionization mode. Method linearity was obeyed within 1–5000 ng mL−1 for both LOS and ROS, while the validation process was performed according to the guidelines adopted by the US-FDA bioanalytical framework. The pharmacokinetic interactions after oral co-administration of both drugs furnished significant changes within their respective pharmacokinetic parameters including peak-plasma concentration, elimination t1/2, AUC, volume of distribution, and plasma clearance. Additionally, a mutual competitive displacement for each drug from their plasma albumin bindings showed a significant impact on drug's pharmacokinetic profile and was demonstrated through molecular modeling investigations. Finally, the presented study laid an evidence for a two-way pharmacological synergism with the combined therapy of LOS and ROS via increased hepatic influx of ROS and peak-plasma concentration of EXP3174, the LOS more potent metabolite. Therefore, the proposed method provides a useful tool for the drug–drug interaction investigations being valuable for prospective bioequivalence studies and therapeutic drug monitoring.