Phase For Chromatographic Separation Research Articles

Simultaneous spectrophotometric and chromatographic determination of Ketorolac and Dexamethasone: Overall assessment regarding environmental Impact, Practicality, and functionality principles

Determination of a drug combination that contains a minor component that is also a poorly UV absorbing analyte represents greet challenges in drug analysis. A fixed-dose ophthalmic combination of ketorolac tromethamine (KET) and dexamethasone sodium phosphate (DEX) (in the ratio of 5:1) is used to relieve post-surgical inflammation and seasonal allergic conjunctivitis due to their analgesic and anti-inflammatory activity. Five spectrophotometric methods and a reversed phase chromatographic separation method were developed and validated for simultaneous determination of both drugs in lab-prepared eye drops. Direct spectrophotometric determination of KET (the major, highly UV absorbing analyte) was achieved from the zero-order UV absorption spectra at 323 nm while DEX (which is the minor, poorly UV absorbing analyte) was quantified after applying several spectrophotometric methods. Either fundamental zero-order spectra or ratio spectra were used, and measurements were done at either single or dual wavelengths. The developed methods were: isosbestic point method, absorption factor method, dual wavelength method, ratio difference UV spectrophotometric method, and simultaneous equation method. The developed spectrophotometric methods determine KET in the linearity range of 2.0–12.0 μg/mL and DEX in the range of 5.0 – 35.0 μg/mL. For accurate spectrophotometric determination of DEX in the ratio of the dosage form, multiple standard addition method was applied. HPLC technique was also applied for separation and quantification of both drugs. Chromatographic separation was attained by using Hypersil ODS-C18 (150 x 4.6 mm, 5 μm) column. The mobile phase was composed of 50 % methanol: 50 % phosphate buffer (pH 2.5). The column compartment was maintained at 25 °C. Flow rate was adjusted at 1.2 mL/min and detection was performed by DAD at 254 nm. The linearity of HPLC method was 5.0–100.0 μg/mL, and 5.0–50.0 μg/mL for KET and DEX, respectively. Simultaneous determination of both drugs was applied to lab-prepared eye drops that contain also benzalkonium chloride as inactive ingredient. The developed methods determined the cited drugs with good and acceptable % recovery. The results of the developed methods and a reported HPLC method were compared using one-way ANOVA test, F-test and student’s t-test at confidence level 95 %, and they show no significant statistical difference. Assessment of greenness of the developed methods in comparison with reported HPLC method was performed using different tools, including analytical eco-scale, GAPI and AGREE. HPLC-EAT was also performed to ensure greenness of developed HPLC method. Moreover, assessment of practicality, applicability, and functionality of developed and reported methods was evaluated by BAGI metric tool and WAC calculator, respectively. The developed methods allow simple, rapid, and accurate analysis of quality control samples that contain KET and DEX.

Design of smart temperature-sensitive terpolymeric hydrogel for multi-applications in liquid chromatography

Hydrogels with a unique three-dimensional network structure have been widely used in a variety of fields. However, hydrogels are prone to swelling under water-rich conditions, which severely limits their application in liquid chromatography. Therefore, producing a hydrogel with reliable performance and good mechanical property is essential. Smart temperature-sensitive chromatographic packings have attracted extensive attentions in recent years. In this work, sodium 4-styrenesulfonate and 1-octadecene were introduced into the poly(N-isopropylacrylamide) hydrogel to improve mechanical property and separation performance. As a consequence, a smart temperature-sensitive terpolymeric hydrogel modified silica stationary phase (ION-hydrogel@SiO2) was synthesized for multimode liquid chromatographic separation. It was found that this new ION-hydrogel@SiO2 column exhibited excellent chromatographic separation ability for a wide range of analytes. To a certain extent, this new column has a higher chromatographic separation efficiency compared to the commercial C18 column and XAmide column. Moreover, the use of low proportion of organic phase in chromatographic separation is conducive to the realization of green chromatography. By investigating the chromatographic separation mechanism, it has been demonstrated that the hydrogen bonding interaction is primarily responsible for the temperature-sensitive behavior of the hydrogel. Finally, the ION-hydrogel@SiO2 column was used for the determination of pyridoxine in the commercially available tablet samples. In conclusion, this study presents a feasible idea for the development of novel copolymer hydrogels as liquid chromatographic stationary phases.

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.

Development and validation of stability indicating HPLC–PDA method for the simultaneous determination of benzoyl peroxide and tretinoin in topical dosage form

BackgroundAcne vulgaris is a very dangerous skin disease leads to psychological disorders. Benzoyl peroxide and tretinoin in combination with topical dosage are used to improve the appearance of acne-prone skin. The study aimed to develop and validate an HPLC–PDA method for the simultaneous estimation of both drugs. Intentional modifications were implemented in the analytical method to get better optimum conditions. The final method was chosen for the reverse phase chromatographic separation by using the C18 column as a stationary phase and 0.01 M phosphate buffer adjusted pH 2.5 mixed with acetonitrile (25:75 v/v) as a mobile phase. The optimized conditions were 1.5 mL/min flow rate, 30 °C column temperature, 5 °C autosampler temperature, and 20 µL injection volume. The wavelength was chosen for detection of Benzoyl peroxide at 272 nm and Tretinoin at 353 nm by utilizing a PDA detector. All standard and sample solutions were made in methanol.ResultsThe developed method exhibited peak retention times of 2.94 min for Benzoyl peroxide and 11.34 min for Tretinoin. This analytical method was proven to be robust, linear in calibration curve, accurate, precise, and specific. The forced degradation studies results showed that a high degree of specificity was obtained by separating both analytes from produced impurities completely.ConclusionsThe developed analytical method is fast, economic and stability indicating. It is useful for routine pharmaceutical analysis where the combination of benzoyl peroxide and tretinoin is formulated for their quality and safety.

Preparation of spherical silica hydroxyl-functionalized covalent organic polymer composites for mixed-mode liquid chromatography.

Covalent organic polymers are an emerging class of amorphous microporous materials that have raised increasing concerns in analytical chemistry due to their unique structural and surface chemical properties. However, the application of covalent organic polymers as mixed-mode stationary phases in chromatographic separations has rarely been reported. Herein, novel spherical silica hydroxyl-functionalized covalent organic polymer composites were successfully prepared via a layer-by-layer approach. The structure and morphology of the materials were carefully characterized by elemental analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller, and contact angle measurements. Baseline separations of various alkylbenzenes, polycyclic aromatic hydrocarbons, and nucleosides and bases were achieved on the prepared stationary phase under reversed-phase/hydrophilic interaction mode. The column efficiencies of 23 853 and 36 580 plates/m were obtained for butylbenzene and uracil, respectively, and the relative standard deviation of the retention time for continuous injections was less than 1.38% (n=10), suggesting satisfactory column efficiency and repeatability. Additionally, this novel stationary phase realized the complete separation of the endocrine-disrupting chemicals in river water. This work affords a new route for synthesizing covalent organic polymers-based mixed-mode stationary phase and further reveals their great potential in chromatographic separation.

Integration of offline two-dimensional chromatography and mass defect filtering-based precursor ion list data acquisition for targeted characterization of diterpenoid alkaloids in the lateral roots of Aconitum carmichaelii

The hyphenated technique of offline two-dimensional (2D) chromatography with high resolution mass spectrometry (MS) was an efficient tool for separation and characterization of components in complex systems such as herbal medicines, especially those co-eluting components or isomers. In this study, we constructed the ultra-performance convergence chromatography (UPC2) × reversed phase (RP) chromatographic separation system and developed a mass defect filtering (MDF)-based precursor ion list (PIL) acquisition method to improve the selectivity and sensitivity of this technique, and the systematic characterization of diterpenoid alkaloids in the lateral roots of Aconitum carmichaelii (namely “Fuzi” in Chinese) was used as an example. The constructed offline 2D separation system showed a good orthogonality of 0.77. Besides, the in-house databases for known and predicted C19- and C20-diterpenoid alkaloids were established by molecular design in Compound Discoverer software for MS data matching and filtering, and two MDF windows were further constructed to screen out more potential diterpenoid alkaloids with novel structures and to obtain the PIL (mass range: even values between 298 and 1020 Da, parent mass width: ±100 mDa) for data acquisition by calculating the m/z values of potential ions using mass range and corresponding mass defect in the MDF windows. In addition, an integrative structure interpretation strategy was developed by integrating elemental composition analysis, ring double bond analysis, neutral loss filtering, diagnostic ion filtering and database matching, etc. As a result, a total of 659 components in the lateral roots of A. carmichaelii were exposed and characterized, including 526 potential new compounds. This strategy showed significant advantages in improving the coverage and selectivity of screening, and could also be applied in systematic characterization of components in other herbal medicines.

Isolation of Rabies Virus Glycoprotein Using Three-Phase Extraction and Characteristics of its Antigenic Properties

The aim of the work was to develop an approach to isolation of rabies virus glycoprotein applying threephase extraction and to characterize its antigenic properties.Materials and methods. Infectious activity of the rabies virus (production strain, “Ovine” GNKI) after long-term storage was restored on white BALB/c mice. The strain was used for cultivation on BHK-21 cells; the culture liquid was concentrated applying ultracentrifugation followed by separation by buoyant density in a sucrose gradient, selection of visually opalescent zones, phase concentration, chromatographic separation on an ENrich™ SEC650 column (Bio-Rad, USA) and selection of monomeric fractions with high serological activity according to the results of Western blotting.Results and discussion. We have demonstrated that preliminary mechanical destruction of brain suspension, extraction of the virus-containing material from the cell suspension through successive low-speed and high-speed centrifugation, separation of the sediment produced in sucrose gradient with further phase concentration and chromatographic separation of the precipitate allows to obtain monomeric antigenic preparations with high serological activity. This methodology has made it possible to obtain an antigen, which is rabies virus glycoprotein with a molecular weight of 67 kDa, and two of its isoforms, having molecular weights of 60 and 54 kDa. The described approach can be viewed as an option for isolation of the rabies virus specific antigen when improving laboratory diagnostics techniques. The resulting antigen is a monomeric discrete containing one fraction with a molecu lar weight of 67 kDa. The data obtained corroborate the high specificity of the antigen and its suitability for the design of enzyme immunoassay and immunochromatographic tests, production of specific immunoglobulins, the study of the antigen/antibody interaction, as well as for the assessment of the protective immunity intensity after vaccination.

NEW RP-HPLC METHOD DEVELOPMENT AND VALIDATION FOR THE ESTIMATION OF ANTIFUNGAL DRUG ITRACONAZOLE IN ITRACONAZOLE LOADED INVASOMES GEL

A new simple, accurate, rapid, selective and robust high pressure liquid chromatography (HPLC) method was developed and validated for estimation of itraconazole (ITZ) in bulk and prepared in house invasomes gel formulation. Acetonitrile and Methanol was used as a mobile phase for chromatographic separation in the ratio of 20mM KH2PO4: Acetonitrile (pH adjusted to 4.0 with OPA) at flow rate of 1.0 ml/min and estimation on Thermo C18 (250 × 4.6 mm) in the ratio of 50:50 v/v at flow rate of 1.0 ml/min. The detection was carried out with UV detector set at 262nm. The retention time for itraconazole was found to be 2.258±0.095 minutes. The linearity range for itraconazole was found to be 5-25 μg/ml with coefficient of linear regression 0.998. The method was validated in accordance with the requirements of International Conference on Harmonization (ICHQ2 A 8 B) guidelines for specificity, linearity, accuracy, precision, LOD 8 LOQ.

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 and Validation of an Up-to-Date Highly Sensitive UHPLC-MS/MS Method for the Simultaneous Quantification of Current Anti-HIV Nucleoside Analogues in Human Plasma.

Therapeutic options to treat HIV infection have widened in the past years, improving both effectiveness and tolerability, but nucleoside reverse transcriptase inhibitors (NRTIs) are still considered the standard backbone of the combination regimens. Therapeutic drug monitoring (TDM) can be useful for these drugs, due to concentration–effect relationship, with risk of ineffectiveness, toxicity or adherence concerns: in this scenario, robust and multiplexed methods are needed for an effective TDM activity. In this work, the first validated ultra-high spectrometry liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) method is described for the high-sensitive simultaneous quantification of all the currently used NRTIs in human plasma, including tenofovir alafenamide (TAF), following FDA and EMA guidelines. The automated sample preparation consisted in the addition of an internal standard (IS) working solution, containing stable-isotope-linked drugs, protein precipitation and drying. Dry extracts were reconstituted with water, then, these underwent reversed phase chromatographic separation: compounds were detected through electrospray ionization and multiple reaction monitoring. Accuracy, precision, recovery and IS-normalized matrix effect fulfilled guidelines’ requirements. The application of this method on samples from people living with HIV (PLWH) showed satisfactory performance, being capable of quantifying the very low concentrations of tenofovir (TFV) in patients treated with TAF.

LC-MS/MS method for quantitation of gemcitabine and its metabolite 2′,2′-difluoro-2′-deoxyuridine in mouse plasma and brain tissue: Application to a preclinical pharmacokinetic study

A simple, sensitive, and relatively fast assay was developed and validated for the quantitation of gemcitabine (dFdC) and its major metabolite 2′,2′-difluoro-2′-deoxyuridine (dFdU) in mouse plasma and brain tissue. The assay used a small sample (25 μL plasma and 5 mg brain) for extraction by protein precipitation. After dilution of the supernatant extract, 1 μL was injected into HPLC system for reverse phase chromatographic separation with a total run time of 8 min. Chromatographic resolution of dFdC and dFdU was achieved on a Gemini C18 column (50 × 4.6 mm, 3 μm) utilizing gradient elution. Multiple reaction monitoring (MRM) with positive/negative ion switching was performed for detection of dFdC and its internal standard (dFdC-IS) in positive ion mode and dFdU and its IS (dFdU-IS) in negative ion mode. Two calibration curves ranging from 5−2000 ng/mL and 250−50,000 ng/mL were generated for dFdC and dFdU in mouse plasma, respectively. For measurement of dFdC and dFdU in mouse brain tissue, another two curves were used ranging from 0.02 to 40 ng/mg and 1–40 ng/mg, respectively. This assay demonstrated excellent precision and accuracy within day and between days for simultaneous measurement of dFdC and dFdU at all the concentration levels in both matrices. The other parameters such as selectivity, sensitivity, matrix effects, recovery, and storage stability were also assessed for both analytes in each matrix. Compared to the previously reported methods, the sample extraction in the current assay was simplified significantly, and the analysis time was greatly shortened. We successfully applied the validated method to the analysis of dFdC and dFdU in mouse plasma, brain, and brain tumor tissue in a preclinical pharmacokinetic study.

LIQUID PHASE CHROMATOGRAPHIC METHODS APPLIED TO DETERMINE EMERGING CONTAMINANTS IN ENVIRONMENTAL SAMPLES

Emerging contaminants are a heterogeneous group of chemicals that include daily personal care products and pharmaceuticals (PPCPs), flame retardants, endocrine-disrupting chemicals (EDCs) and nanoparticles (NPs) present in environment which are unregulated. In this review, we present the methods of analysis conducted by INCD-ECOIND regarding some classes of emerging contaminants (neonicotinoid pesticides, beta-blocker drugs) that are not regulated by the legislation, in different types of environmental samples (wastewater, surface water). The present review presents the selective solid-phase extraction (SPE) methods used for isolation of the targeted compounds from aqueous matrices and also the main instrumental parameters of the separation and detection process. After extraction, the compounds were subjected to liquid phase chromatographic separation with mass spectrometric detection (UHPLC-MS/MS). Finally, the methods were applied in the determination of compounds from different categories of water, carrying out studies on the efficiency of elimination of compounds in several municipal wastewater treatment plants (WWTPs). In addition, the impact of the treatment plants on some receiving surface water used to obtain drinking water was studied.

LC-MS/MS method for quantitation of the CK2 inhibitor silmitasertib (CX-4945) in human plasma, CSF, and brain tissue, and application to a clinical pharmacokinetic study in children with brain tumors

Silmitasertib (CX-4945) as a potent and selective inhibitor of CK2 exhibited promising in vitro and in vivo anti-cancer activity. An assay employing cation-exchange solid phase extraction (SPE) followed by LC-MS/MS analysis was successfully developed and validated for the quantitation of silmitasertib in human plasma, brain tissue, and human cerebrospinal fluid (CSF). Reverse phase chromatographic separation was achieved using Synergi™ hydro-RP column (4 μm, 75 × 2.0 mm) and gradient elution with 5 mM ammonium formate aqueous solution (pH 6.5) as mobile phase A and 0.1% formic acid in acetonitrile as mobile phase B. Multiple reaction monitoring (MRM) transition of m/z 350.2 → 223.2 and m/z 316.2 → 223.2 were chosen for detection of silmitasertib and internal standard (CX-4786) respectively. Since silmitasertib concentration in patient plasma is expected to be in a wide range due to the study design, two calibration curves with range 0.2–125 ng/ml and 32–20,000 ng/ml were established. A different curve ranging from 2 to 40 ng/g was used for measurement of silmitasertib in brain tissue, while another calibration curve ranging from 0.2 to 20 ng/ml was established for CSF. All these calibration curves corresponding to different matrices showed good linearity (R2 > 0.99) over the concentration range. This assay demonstrated excellent precision below 15% and accuracies between 85% and 115% within–day and between–day for all the concentration levels in each matrix. This assay was also validated for each matrix for selectivity, sensitivity, matrix effects, recovery, and stability. We applied the validated method to the analysis of plasma silmitasertib for a clinical study.

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.

A patient-centric liquid chromatography-tandem mass spectrometry microsampling assay for analysis of cannabinoids in human whole blood: Application to pediatric pharmacokinetic study

Medical cannabis is increasingly used for the treatment of various ailments in children and adults. Three major cannabinoids in cannabis are delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN). There is a growing need to develop and utilize a patient-centric blood microsampling methodology to enable clinical trials and facilitate therapeutic drug monitoring. We have employed the volumetric absorptive microsampling (VAMS™) devices that enables accurate and precise collection of a fixed volume (20 µL) of blood, minimizing the impact of hematocriton accurate quantitation. We developed an ultra-performance liquid chromatographic method with tandem mass spectrometry detection for the quantification of three cannabinoids (THC, CBD, and CBN) employing deuterium labelled internal standards (THC-D3, CBD-D3, and CBN-D3). Sample extraction of VAMS™ devices, followed by solid phase extraction, reverse phase chromatographic separation, and selective detection using tandem mass spectrometry with a 6-minute runtime per sample was developed. Standard curves were linear between 1 and 500 ng/mL for THC and 0.5–500 ng/mL for CBD and CBN. Intra-day accuracies were within 91.3–112% while inter-day accuracies were within 94.4–107% with both having precisions (CV (%)) of <13% based on quality control samples in a three day validation study for all three cannabinoids. Analytes were stable in human whole blood under assay conditions (60 h at room temperature and 24 h in autosampler post-extraction). Dried microsamples were stable for one week at 40 °C, two weeks (15 days) under different storage conditions (room temperature, 4, −20 and −78 °C), one month (29 days) at −20 and −78 °C and three months (68 days) at −78 °C. This assay provides an efficient quantitation of THC, CBD, and CBN in VAMS™ devices and is currently being implemented for pediatric clinical trials.

Simultaneous determination of ten nonsteroidal anti-inflammatory drugs from drinking water, surface water and wastewater using micro UHPLC-MS/MS with on-line SPE system

A simple, accurate and sensitive micro UHPLC-MS/MS method was developed and validated for the simultaneous determination of 10 nonsteroidal anti-inflammatory drugs (NSAIDs) from different environmental matrices. The micro LC ‒ on-line SPE method described in this study allowed to determine the selected drugs at ultra-trace levels without the most commonly used complex off-line SPE sample preparation procedures. The presented method is capable of reaching satisfactory low LOQ values with analysing the sample directly after being diluted with water. In order to attain high sensitivity, mass spectrometry was carefully optimized for the analysis of the drugs. Fenoprofen, flurbiprofen and naproxen were found to produce CO2 loss during ionization, forming intense [M-H-CO2]- ions instead of [M-H]-. All the other compounds were analyzed through their [M+H]+ and [M-H]- ions. Effect of mobile phase pH on ionization was also studied. Lower pH resulted in higher ion intensities. For this reason, a reversed phase chromatographic separation was applied at pH 3.1 with formic acid at concentration of 0.01%. Matrix effects have been evaluated during validation and sample dilution was optimized focusing on the lowest achievable LOQ values. Analytes were determined from drinking water directly, from surface water and wastewater following dilution with purified water by 2 : 8 (v/v) and 1 : 9 (v/v), respectively. Finally, the method was applied to real sample analysis.

Influenza DNA vaccine purification using pHEMA cryogel support

Influenza virus is a huge financial and social burden for health care systems over the world. Currently, traditional approaches are not effective in the fight of the epidemy and new alternatives like DNA vaccines have been developed. However, the downstream process of DNA vaccines is a constant challenge in the biotechnology industry. Cryogels has several advantages over traditional supports and have been tested as stationary phase in chromatographic separations. In this work, a method based on poly(2-hydroxyethyl methacrylate) cryogel was used to purify the plasmid NTC7482-41H-VA2 HA, which express the Influenza hemagglutinin gene. For this purpose, the cryogel was synthesized by cryo-polymerization of 2-hydroxyethyl methacrylate and characterized by scanning electron microscopy. The purification of supercoiled isoform of the plasmid NTC7482-41H-VA2 HA from a clarified lysate sample was achieved in a two-step experiment using NaCl and the dynamic binding capacity of pHEMA cryogel was determined. The assessment of DNA vaccine allowed to conclude that the level of contaminants such as proteins, genomic DNA, RNA and endotoxins are in accordance with FDA agency.

Development and Validation of a HPLC-based Bioanalytical Method for Lorcaserin using Solid Phase Extraction and Application to a Pharmacokinetic Study in Rats

A rapid, precise, accurate, specific and simple high performance liquid chromatography method for estimation of lorcaserin hydrochloric in human plasma, using metoprolol as an internal standard, was developed and validated as per the regulatory requirements. Sample preparation included solid phase extraction and chromatographic separation was performed using a Phenomenex Luna C18 column (250×4.6 mm i.d, 5 µ particle size), with phosphate buffer (pH 3):acetonitrile:methanol (65:20:15) as the mobile phase at a flow rate of 1.0 ml/min. Wavelength of detection was 222 nm. Retention times of internal standard and lorcaserin HCl were found to be 5.15 and 7.19 min, respectively. The method was developed and tested in the linearity range of 500 to 3000 ng/ml. The method was validated for accuracy, precision, linearity, recovery and stability in compliance to international regulatory guidelines.

Molecular imprinting technology and its application in terpenoids

Molecular imprinting technology is widely used in the separation and analysis of compounds such as flavonoids, alkaloids and polyphenols, due to its high selectivity and specific recognition and so on. However, no much of attention has been paid to the terpenoids. This paper is aimed to not only review the effects of common synthetic elements such as functional monomers, cross-linking agents and porogens on the polymer properties, but also highlight the application of terpene molecular imprinting in solid phase extraction, sensor, membrane separation and chromatographic separation by means of statistical analysis of literature. Furthermore, the shortcomings and improvement directions are discussed.We believed that this paper could provide references for better applications of molecular imprinting techniques to the analysis of terpenoid compounds.

Determination of tryptophan derivatives in kynurenine pathway in fermented foods using liquid chromatography tandem mass spectrometry

This study aimed to develop an analytical method for the determination of tryptophan and its derivatives in kynurenine pathway using tandem mass spectrometry in various fermented food products (bread, beer, red wine, white cheese, yoghurt, kefir and cocoa powder). The method entails an aqueous extraction and reversed phase chromatographic separation using pentafluorophenyl (PFP) column. It allowed quantitation of low ppb levels of tryptophan and its derivatives in different fermented food matrices. It was found that beer samples were found to contain kynurenine within the range of 28.7±0.7μg/L and 86.3±0.5μg/L. Moreover, dairy products (yoghurt, white cheese and kefir) contained kynurenine ranging from 30.3 to 763.8μg/kg d.w. Though bread samples analyzed did not contain kynurenic acid, beer and red wine samples as yeast-fermented foods were found to contain kynurenic acid. Among foods analyzed, cacao powder had the highest amounts of kynurenic acid (4486.2±165.6μg/kgd.w), which is a neuroprotective compound.