LC System Research Articles

Lecithin liposomes and microemulsions as new chromatographic phases

Lecithins are phospholipidic mixtures that can be part of microemulsions and liposomes. In this work, ready-to-use preparations of lecithin have been tested as pseudostationary and mobile phases in EKC and LC, respectively. The selectivity of two EKC systems, one based on lecithin microemulsions (LMEEKC) and another on liposomes (LLEKC), and of a LC system based on lecithin microemulsions (MELC) has been evaluated through the solvation parameter model. In all cases, solute volume and hydrogen-bond basicity are the main descriptors that drive the partition process. While solute volume favors the retention of solutes, hydrogen-bond basicity has the contrary effect. In lecithin-based EKC systems the hydrogen-bond acidity of the solute leads to a higher retention while in the lecithin-based LC system a minor retention is produced. The three lecithin systems have been compared through the solvation parameter model to other chromatographic systems, most of them containing phospholipids. Principal component analysis reveals that lecithin systems cluster together with the other EKC systems based on phospholipids, with an immobilized artificial membrane (IAM) LC system, with the octanol/water reference partition system, and with a SDS-based microemulsion. Thus, they all show similar selectivity. However, the great advantage of using the ready-to use lecithin systems is that the laborious liposome preparation is avoided, and that their commercial availability makes them more affordable than IAM LC columns. Finally, taking into account that lecithin has a high semblance to the mammalian cell membranes composition, the ability of the three lecithin systems to mimic the pass of the solutes through the membranes has been evaluated. Experimental determinations have demonstrated that the skin partition of neutral solutes can be easily emulated, especially using the lecithin-microemulsion EKC method. The model is robust and shows good prediction ability.

Dewey Decimal Classification Trending Downward in U.S. Academic Libraries, but Unlikely to Disappear Completely

A Review of:
 Lund, B., & Agbaji, D. (2018). Use of Dewey Decimal Classification by academic libraries in the United States. Cataloging and Classification Quarterly, 56(7), 653-661. https://doi.org/10.1080/01639374.2018.1517851 
 Abstract
 Objective – To determine the current use of Dewey Decimal Classification in academic libraries in the United States of America (U.S.).
 Design – Cross-sectional survey using a systematic sampling method.
 Setting – Online academic library catalogues in the U.S.
 Subjects – 3,973 academic library catalogues.
 Methods – The researchers identified 3,973 academic libraries affiliated with degree-granting post-secondary institutions in the U.S. The researchers searched each library’s online catalogue for 10 terms from a predetermined list. From the results of each search, the researchers selected at least five titles, noted the classification scheme used to classify each title, and coded the library as using Dewey Decimal Classification (DDC), Library of Congress Classification (LCC), both DDC and LCC, or other classification schemes.
 Based on the results of their data collection, the researchers calculated totals. The totals of this current study’s data collection were compared to statistics on DDC usage from two previous reports, one published in 1975 and one in 1996. The researchers performed statistical analyses to determine if there were any discernible trends from the earliest reported statistics through to the current study.
 Main Results – Collections classified using DDC were present in 717 libraries (18.9%). Adjusting for the increase in the number of academic libraries in the U.S. between 1975 and 2017, DDC usage in academic libraries has declined by 56% in that time frame. The number of libraries with only DDC in evidence is unreported.
 Conclusion – The previous four decades have seen a significant decrease in the use of DDC in U.S. academic libraries in favour of LCC; however, the rate at which DDC has disappeared from academic libraries has slowed dramatically since the 1960s. There is no clear indication that DDC will disappear from academic libraries completely.

Quantitation of Single and Combinatorial Histone Modifications by Integrated Chromatography of Bottom-up Peptides and Middle-down Polypeptide Tails.

The analysis of histone post-translational modifications (PTMs) by mass spectrometry (MS) has been critical to the advancement of the field of epigenetics. The most sensitive and accurate workflow is similar to the canonical proteomics analysis workflow (bottom-up MS), where histones are digested into short peptides (4-20 aa) and quantitated in extracted ion chromatograms. However, this limits the ability to detect even very common co-occurrences of modifications on histone proteins, preventing biological interpretation of PTM crosstalk. By digesting with GluC rather than trypsin, it is possible to produce long polypeptides corresponding to intact histone N-terminal tails (50-60 aa), where most modifications reside. This middle-down MS approach is used to study distant PTM co-existence. However, the most sensitive middle-down workflow uses weak cation exchange-hydrophilic interaction chromatography (WCX-HILIC), which is less robust than conventional reversed-phase chromatography. Additionally, since the buffer systems for middle-down and bottom-up proteomics differ substantially, it is cumbersome to toggle back and forth between both experimental setups on the same LC system. Here, we present a new workflow using porous graphitic carbon (PGC) as a stationary phase for histone analysis where bottom-up and middle-down sized histone peptides can be analyzed simultaneously using the same reversed-phase buffer setup. By using this protocol for middle-down sized peptides, we identified 406 uniquely modified intact histone tails and achieved a correlation of 0.85 between PGC and WCX-HILICLC methods. Together, our method facilitates the analysis of single and combinatorial histone PTMs with much simpler applicability for conventional proteomics labs than the state-of-the-art middle-down MS.

Application of HPLC for Evaluation and Standardisation of Hawthorn Flower Herbal Substance

The process of harmonisation of Russian and foreign approaches and requirements in the field of medicines quality assurance calls for revision of quality control procedures included in various regulations and guidelines. The monograph FS.2.5.0062.18 “Hawthorn flowers” of the State Pharmacopoeia of the Russian Federation XIV edition includes a test procedure for determination of flavonoids by a chromatospectrophotometric method. This procedure does not take into account current scientific capabilities and has a number of shortcomings, therefore it was necessary to revise the existing test procedure and develop a new approach to the standardisation of the hawthorn flower herbal substance.The objectiveof the studywas to develop an assay method for standardisation and evaluation of hawthorn flower using high performance liquid chromatography (HPLC).Materials and methods:the study was performed using samples of hawthorn flowers by Russian manufacturers. Quercetin (USP RS) and Hyperoside (HWI, primary standard) were used as the reference standards. The HPLC analysis was performed using an Infinity II 1260 DAD LC system (Agilent), and the UV spectra were recorded on a Cary 100 Varian spectrophotometer. A TLC Visualizer (CAMAG) was used to obtain digital images of thin layer chromatography plates.Results:the authors developed an HPLC test procedure for quantitative determination of total flavonoids, expressed as hyperoside, in hawthorn flowers. The developed procedure gives reliable and reproducible results and is characterised by high sensitivity and selectivity. The results of quantitative determination of the total flavonoid content in hawthorn flowers were used to propose the standard for the total content of flavonoids, expressed as hyperoside, of “not less than 0.5%”.Conclusions:the developed assay method for determination of active pharmaceutical ingredients in hawthorn flower products by HPLC can be recommended for inclusion into the Assay part of the “Hawthorn Flowers” monograph of the State Pharmacopoeia of the Russian Federation.

CREATING WALLONIA'S NEW VERY HIGH RESOLUTION LAND COVER MAPS: COMBINING GRASS GIS OBIA AND OTB PIXEL-BASED RESULTS

Abstract. The Walloon region of Belgium has launched a research project that aims at elaborating a methodology for automated, high-quality land cover mapping, based primarily on its yearly 0.25m orthophoto coverage. Whereas in urban areas an object-based (OBIA) approach has been the privileged path in the last years as it allows taking into account shape information relevant for the characterization of man-made constructions, such an approach has its limits in the rural and more natural areas due to increased difficulties for segmentation and less sharp boundaries, thus calling for a pixel-based approach. The project thus consists in developing a combination of methods, and to integrate their results through an ensemble fusion approach. As many of the more natural land cover classes have temporal profiles which cannot be detected in a one-date orthoimage, Sentinel 1 and 2 data are also included in order to take advantage of their higher spectral and temporal resolution. All methods are trained using existing regional databases. In a second step, we combine the different LC classification results by fusioning them into one high-accuracy (over 90% OA) product, using a series of different approaches ranging from rule-based to machine learning to the Dempster-Shafer method. The entire toolchain is based on free and open source software, mainly GRASS GIS and Orfeo ToolBox. Results indicate the importance of the quality of the individual classifications for the fusion results and justify the choice of combining OBIA and pixel-based approaches in order to avoid the pitfalls of each.

A Green Ultrasound-Assisted Extraction Optimization of the Natural Antioxidant and Anti-Aging Flavonolignans from Milk Thistle Silybum marianum (L.) Gaertn. Fruits for Cosmetic Applications.

Silybum marianum (L.) Gaertn. (aka milk thistle) constitutes the source of silymarin (SILM), a mixture of different flavonolignans and represents a unique model for their extraction. Here we report on the development and validation of an ultrasound-assisted extraction (UAE) method of S. marianum flavonolignans follow by their quantification using LC system. The optimal conditions of this UAE method were: aqueous EtOH 54.5% (v/v) as extraction solvent, with application of an ultrasound (US) frequency of 36.6 kHz during 60 min at 45 °C with a liquid to solid ratio of 25:1 mL/g dry weight (DW). Following its optimization using a full factorial design, the extraction method was validated according to international standards of the association of analytical communities (AOAC) to ensure precision and accuracy in the quantitation of each component of the SILM mixture. The efficiency of this UAE was compared with maceration protocol. Here, the optimized and validated conditions of the UAE allowed the highest extraction yields of SILM and its constituents in comparison to maceration. During UAE, the antioxidant capacity of the extracts was retained, as confirmed by the in vitro assays CUPRAC (cupric ion reducing antioxidant capacity) and inhibition of AGEs (advanced glycation end products). The skin anti-aging potential of the extract obtained by UAE was also confirmed by the strong in vitro cell-free inhibition capacity of both collagenase and elastase. To summarize, the UAE procedure presented here is a green and efficient method for the extraction and quantification of SILM and its constituents from the fruits of S. marianum, making it possible to generate extracts with attractive antioxidant and anti-aging activities for future cosmetic applications.

African baobab (Adansonia digitata) fruit as promising source of procyanidins

Baobab is an endemic African plant rich in health-promoting compounds and still not extensively studied. Characterization of bioactive molecules in baobab fruit by means of LC system coupled with a photodiode array and a triple quadrupole mass spectrometer detector is here reported. This work provides a qualitative and quantitative profile of polyphenols in baobab pulp, shell, kernel and seeds. Baobab pulp is a rich source of ascorbic acid, (−)-epicatechin and procyanidin B2 (135.6, 104.8, and 100.1 mg/100 g). Moreover, a HPLC preparative method to isolate procyanidin fraction from pulp was developed, revealing how the antioxidant activity of baobab pulp not only depend on the ascorbic acid content but also on the presence of procyanidins. The use of baobab fruit pulp as promising healthy food or food supplement is also discussed.

Evaluating Knowledge Organization in Developed and Developing Countries: A Comparative Analysis of Dewey Decimal and Library of Congress Classification Scheme Preference and use in the United States and Nigeria

ABSTRACT This comparative study investigates the use of and preference towards the two major academic library classification schemes – Dewey Decimal Classification (DDC) and Library of Congress Classification (LCC) – in developed (United States) and quickly developing (Nigeria) countries. The findings reveal that approximately 81% of academic libraries in the U.S. and 93% in Nigeria use LCC for classifying the majority of their collections. Academic library employees in both countries show a strong preference for LCC, except for those employees working in a library that currently uses DDC, in which case these employees tend to prefer DDC over LCC. The comparison between results among the United States and Nigeria provides insight into two different histories and narratives about academic library classification, which may prove beneficial to those libraries investigating classification or a reclassification decision.

Synthesis and properties of fluorine tail-terminated cyanobiphenyls and terphenyls for chemoresponsive liquid crystals

ABSTRACTA series of fluorine tail-terminated alkoxy and alkyl cyanobiphenyl compounds and some cyano-p-terphenyl derivatives were synthesised and mesogenic properties described. Comparison with the non-fluorinated K series and M series indicates that the terminal fluorine atom generally decreases the transition temperatures and, more interestingly, depresses the formation of a smectic phase. Several binary LC mixtures formed by the fluorine tail-terminated compounds were found exhibiting promising room temperature nematic phases with wide ranges. The mixture F7OCB and F8OCB shows homeotropic ordering at the metal salts-decorated surfaces and planar ordering at the free surface, which may have potential application in designing a more sensitive and faster LC system to targeted analytes.

Offline preparative 2-D polar-copolymerized reversed-phase chromatography × zwitterionic hydrophilic interaction chromatography for effective purification of polar compounds from Caulis Polygoni Multiflori

Polar compounds are abundant in the water decoction of Traditional Chinese Medicines (TCMs) and possess important biological activities. However, purifying these compounds has faced great difficulties largely due to poor retention and insufficient selectivity. To solve this problem, an offline orthogonal 2-D RPLC coupled with hydrophilic interaction chromatography (HILIC) method was developed to achieve purification of polar compounds from Caulis Polygoni Multiflori. A polar-copolymerized XAqua C18 column and a zwitterionic Click XIon column exhibited satisfactory retention and separation for polar compounds. Therefore, they were adopted to construct the offline 2-D LC system. Furthermore, the method presented a high orthogonality, which was calculated to be 72%. The XAqua C18 column was used in the first dimension to fractionate the 5.1 g polar fraction with a recovery of 85% within 10 h. In the second dimension, three representative fractions were purified using the Click XIon column. Finally, three compounds with purity higher than 95% were identified for the first time from this plant. This offline 2-D RPLC/HILIC method was shown to be an effective approach to purifying polar compounds from Caulis Polygoni Multiflori.

Primary Step Towards In Situ Detection of Chemical Biomarkers in the UNIVERSE via Liquid-Based Analytical System: Development of an Automated Online Trapping/Liquid Chromatography System.

The search for biomarkers in our solar system is a fundamental challenge for the space research community. It encompasses major difficulties linked to their very low concentration levels, their ambiguous origins (biotic or abiotic), as well as their diversity and complexity. Even if, in 40 years’ time, great improvements in sample pre-treatment, chromatographic separation and mass spectrometry detection have been achieved, there is still a need for new in situ scientific instrumentation. This work presents an original liquid chromatographic system with a trapping unit dedicated to the one-pot detection of a large set of non-volatile extra-terrestrial compounds. It is composed of two units, monitored by a single pump. The first unit is an online trapping unit able to trap polar, apolar, monomeric and polymeric organics. The second unit is an online analytical unit with a high-resolution Q-Orbitrap mass spectrometer. The designed single pump system was as efficient as a laboratory dual-trap LC system for the analysis of amino acids, nucleobases and oligopeptides. The overall setup significantly improves sensitivity, providing limits of detection ranging from ppb to ppt levels, thus meeting with in situ enquiries.

A rapid, simple and sensitive liquid chromatography tandem mass spectrometry assay to determine amoxicillin concentrations in biological matrix of little volume

To assess pharmacokinetics of amoxicillin (AMX) in mice, limitations such as a small sampling volume and low drug concentrations have to be addressed. Similar challenges are faced in a clinical framework, e.g. for therapeutic drug monitoring in neonates or small-scale in vitro investigations. An assay enabling quantification of small sample volumes but still at very low concentrations covering a broad concentration range is thus needed.A simple, rapid and highly sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and successfully validated for quantification of AMX in mouse serum according to European Medicines Agency guidelines. Sample preparation enabled the use of only 10 μL of serum, which is 5-fold less than comparable assays and allows to reduce the number of mice used in pharmacokinetic studies. After protein precipitation with 40 μL chilled methanol and dilution of the supernatant with water, the sample was injected into the LC system on a Poroshell 120 Phenyl Hexyl column (2.1 × 100 mm, 2.7 μm). Chromatographic separation was achieved using a gradient method consisting of acetonitrile and ultra-pure water, both with 0.1% (V/V) formic acid. Positive electrospray ionisation in multiple reaction monitoring mode was used for detection and quantification of AMX. Application to murine study samples demonstrated the reliability of the developed method being accurate and precise with a quantification range from 0.01 to 10 μg/mL. The assay is easily transferable due to a simple sample preparation and confirmed stability of AMX under various applied conditions.

New Concepts for the Determination of Oxidation Efficiencies in Liquid Chromatography-Isotope Ratio Mass Spectrometry.

In liquid chromatography coupled to isotope ratio mass spectrometry (LC-IRMS), analytes are separated on an LC system and consecutively oxidized to CO2, which is required for the determination of compound-specific carbon isotope ratios. Oxidation is performed in an online reactor by sulfate radicals. Reaction conditions in the interface depend on the flow conditions determined by the LC method and the flow rates and concentrations of oxidation agent and phosphoric acid added in the interface. To determine accurate isotope ratios, a quantitative conversion of the carbon contained in the analyte to the CO2 measurement gas is a prerequisite. Oxidation efficiencies are not commonly evaluated during method development, although certain analytes are known to be difficult to be oxidized by sulfate radicals. For the assessment of the oxidation efficiency of the LC-IRMS system, three different approaches were evaluated. (1) Residual organic carbon in the eluent stream of the interface was determined to calculate oxidation yields depending on the initial analyte concentration. (2) The IRMS response was calibrated to an inorganic carbon reference material to determine oxidation efficiencies with the help of the IRMS as a detector. (3) The oxidation temperature was deliberately reduced while monitoring the δ13C and signal intensity. The common assumption that a linear relation of IRMS signal to analyte concentration is an indicator for complete oxidation in LC-IRMS could be disproved. All three approaches can be applied for future method development in LC-IRMS, monitoring of existing flow injection applications, as well as for verification of complete oxidation in established LC-IRMS methods.

HPLC-determination of active components in dietary supplement «L-CARNITINE smart»

Dietary supplements are compositions of biologically active substances intended for consumption with food or addition to food products for the purpose of optimization of metabolic processes and functions of the human body. The dietary supplements include: vitamins, trace elements, amino acids, enzymes, proteins, probiotics, oils that can provide antioxidant, detoxifying, immunomodulatory, adaptogenic effects, etc.
 Detection of physiologically active components in dietary supplements is a difficult task and requires the use of modern highly informative research methods. One of the most powerful and versatile methods of determination is the method of high performance liquid chromatography (HPLC), combining the selective separation of the studied mixtures and high sensitivity.
 The purpose of this study was to develop a simple, rapid and selective method for determining ascorbic acid and L-carnitine L-tartrate in a multicomponent dietary supplement, produced in the form of sachets, using HPLC with spectrophotometric detection.
 The object of the study is the dietary supplement «L-CARNITINE smart», powder for oral solution of 16 g each in a sachet (INTERСHЕM). For the quantitative determination of the applied method of high-performance liquid chromatography. Chromatography was performed on an Agilent 1260 Infinity 2D LC System (USA) liquid chromatograph with a UV detector.
 The optimal conditions for the analysis have been experimentally determined: the type of sorbent, the composition of the eluent and its gradient, the wavelength and the detection time for ensuring the release of all components (including auxiliary substances) from the column, selective separation of ascorbic acid, potassium acesulfame and L-carnitine L-tartrate, minimization analysis time. The method has been validated according to the following parameters: specificity, linearity, accuracy, limit of quantitation.

Metabolite Profiles of the Cerebrospinal Fluid in Neurosyphilis Patients Determined by Untargeted Metabolomics Analysis.

The mechanism underlying the stealth property of neurosyphilis is still unclear. Global metabolomics analysis can provide substantial information on energy metabolism, physiology and possible diagnostic biomarkers and intervention strategies for pathogens. To gain better understanding of the metabolic mechanism of neurosyphilis, we conducted an untargeted metabolomics analysis of cerebrospinal fluid (CSF) from 18 neurosyphilis patients and an identical number of syphilis/non-neurosyphilis patients and syphilis-free patients using the Agilent, 1290 Infinity LC system. The raw data were normalized and subjected to subsequent statistical analysis by MetaboAnalyst 4.0. Metabolites with a variable importance in projection (VIP) greater than one were validated by Student’s T-test. A total of 1,808 molecular features were extracted from each sample using XCMS software, and the peak intensity of each feature was obtained. Partial-least squares discrimination analysis provided satisfactory separation by comparing neurosyphilis, syphilis/non-neurosyphilis and syphilis-free patients. A similar trend was obtained in the hierarchical clustering analysis. Furthermore, several metabolites were identified as significantly different by Student’s T-test, including L-gulono-gamma-lactone, D-mannose, N-acetyl-L-tyrosine, hypoxanthine, and S-methyl-5′-thioadenosine. Notably, 87.369-fold and 7.492-fold changes of N-acetyl-L-tyrosine were observed in neurosyphilis patients compared with syphilis/non-neurosyphilis patients and syphilis-free patients. These differential metabolites are involved in overlapping pathways, including fructose and mannose metabolism, lysosomes, ABC transporters, and galactose metabolism. Several significantly expressed metabolites were identified in CSF from neurosyphilis patients, including L-gulono-gamma-lactone, D-mannose, N-acetyl-L-tyrosine, and hypoxanthine. These differential metabolites could potentially improve neurosyphilis diagnostics in the future. The role of these differential metabolites in the development of neurosyphilis deserves further exploration.

Knowledge and Skill Requirements for Health Science Library Professionals in India: A Survey

The survey method was considered most appropriate for this study because, it measures users background, experience and what they know about knowledge and skills in professional development in enhancing their knowledge in day to day working environment and it is well suited to the research questions taken up for this study. A total of 218 questionnaires were administered personally and 183 dully- filled-in questionnaire for received with response rate of 83.94% and were considered for analysis. The study findings were that 66.67% knew Dewey Decimal Classification (DDC), the National Library of Medicine Classification (NLM) with 14.75%.The response “No Answer” with 15.3% connotes these libraries have not classified their collection. Only 3.28% knew Library of Congress Classification though it is not much used in Indian libraries probably the respondents’ knowledge of this would be from their study. The mean and standard deviation are computed and ranks were assigned to each of the Medical databases corresponding to the respective designations. This comparison found MedInd/IndMed ranking is much higher than MEDLINE. So the data has no uniformity and conformity with the content and therefore the ranking are not commensurate with the subject content and wider use of the databases worldwide.

Radiochemical and analytical aspects of inter-institutional quality control measurements on radiopharmaceuticals

BackgroundClinically applied radiopharmaceuticals have to meet quality release criteria like a high radiochemical yield and radiochemical purity. Many radiopharmaceuticals do not have marketing authorization and have no dedicated monograph within the European pharmacopeia, therefore general monographs on quality control have to be applied for clinical applications. These criteria require standardization and validation in labeling and preparation, including QC measurements according to well-defined standard operation procedures. QC measurements however, are often based on detection techniques specific for a certain LC-system. Multi-institutional research and development of new radiopharmaceuticals lead to an increase in multicenter trials. Although all institutes’ radiopharmacies are using the same standardized labeling and operation procedures, they often use different LC and radiodetection systems. Here we present a comparison of QC assessments for 3 radiopharmaceuticals with focus on the interpretation of chromatograms, data-output and potential differences in local practical performances of QC on (U)HPLC.MethodsQC assessments for [111In]In-CCK, [68Ga]Ga-Bombesin and [177Lu]Lu-PSMA analogs were compared. Two of the radiopharmaceutical QC assessments were also applied in other institutes using their own HPLC-systems and concordant software. Data from the HPLC-injections and measurements is processed and summarized in chromatograms, based on a variety of smoothing algorithms for which different software programs are applied. Described radiopeptides were labeled and analyzed according their standardized labeling and operation procedures.ResultsIntegration of main peaks on chromatograms resulted in a range of RCP, depending on the smoothing algorithm used. [111In]In-CCK(A), 68Ga-Bombesin(B) and [177Lu]Lu-PSMA(C) analogs had a RCP range of 88%–96%(A), 89–95%(B) and 92–99%(C) respectively. Important factors affecting final RCP value were site specific background radiation-levels, intrinsic system properties such as noise and sensitivity, personal interpretation e.g. peak-tailing and smoothing algorithms.ConclusionMeasurement of RCP shows a strong method- and system-dependency, even when parameters are validated, standardized and SOP are followed. Release criteria are frequently based on RCP data from one central location. The lack of inter inter institutional validation and standardization in RCP determination makes the results therefore rather arbitrary. For multicenter trials, we recommend to compare locally determined RCP under validated and standardized conditions of in-line activity detection between institutes for each radiopharmaceutical.

Simultaneous Determination of 15 Flavonoids in Scutellaria barbata-Hedyotis diffusa Herb Pair by HPLC Q-TOF MS.

Background: The Scutellaria barbata-Hedyotis diffusa herb pair has appeared in classical prescriptions and has usually been used for the treatment of cancer and inflammatory conditions. Objective: For quality control of this herb pair, a rapid and reliable HPLC-quadrupole-time-of-flight(Q-TOF)-MS method was used for the simultaneous determination of alpinetin, apigenin-7-O-β-D-glucopyranoside, scutellarein, apigenin, quercetin-3-O-β-D-glucopyranoside, wogonoside, quercetin, amentoflavone, wogonin, chrysin, luteolin, rutin, naringenin, baicalein, and baicalin in the S. barbata-H. diffusa herb pair. Methods: LC-MS analysis was performed on a Shimadzu HPLC 20ADXR LC system in-line with an AB-SCIEX 5600 Triple TOF mass spectrometer. Results: The calibration curves showed good linearity in a relatively wide concentration range (r >0.996). The LOD and LOQ were less than 20 and 68 ng/mL, respectively. The relative standard deviation (RSD) values of intraday and inter-day precision were <3.31% for all the analytes. The recoveries of the method were in the range of 94.6-106.0%, with RSD <4.72%. The RSD values of peak areas in the stability study were not more than 4.28% for all analytes within 2 days. These results revealed that the method exhibited good sensitivity, precision, accuracy, and stability. Conclusions: This method could be applied to the quantitative determination of 15 flavonoids in the S. barbata - H. diffusa herb pair. Highlights: (1) The established method of HPLC-Q-TOF-MS is simple, fast, sensitive, and reliable. (2) 15 Flavonoids in the S. barbata-H. diffusa herb pair were simultaneous determined.

Retention Modeling of Gradient Elutions: Application of Iso-to-Grad Approach for LC Systems with Dual-Species Eluent

Development of new chromatographic method is often time-consuming and may be shortened by mathematical modeling. Unfortunately, many of the models are limited for predefined elution programs only. The integral model uses iso-to-grad approach to transfer information from isocratic to gradient elution without such limitations, which was successfully tested for IC and HPLC using single-species eluents. Here its applicability was tested on systems using more complex eluents. An HPLC analysis of emerging contaminants using methanol/acetonitrile/water eluent was performed. Four different integral models were developed and validated. The models showed good predictive ability.

ВМІСТ КИСЛОТ ГІДРОКСИКОРИЧНИХ У ТРАВІ ТА КОРЕНЕВИЩАХ І КОРЕНЯХ БЕДРИНЦЮ ЛОМИКАМЕНЕВОГО (PIMPINELLA SAXIFRAGA L.)

Вступ. Бедринець ломикаменевий (Pimpinella saxifraga L.) з родини селерові (Apiaceae) здавна у народній медицині застосовують як відхаркувальний, сечогінний, протизапальний, седативний, болетамувальний засіб. Його рекомендують при катарі дихальних шляхів, трахеїті, бронхіті, пневмонії, ларингіті, астмі, коклюші, водянці, сольових діатезах, захворюваннях печінки, атонії кишечника, хронічному гастриті зі зниженою кислотністю, подагрі, набряках та метеоризмі. З лікувальною метою використовують в основному кореневища і корені рослини. Відомо близько 200 видів роду Бедринець (Pimpinella L.), поширених в Азії, Європі й Африці. В Україні зустрічаються 5 видів; найпоширенішим є бедринець ломикаменевий.&#x0D; Мета дослідження – встановити наявність і визначити кількісний вміст кислот гідроксикоричних у траві та підземних органах бедринцю ломикаменевого.&#x0D; Методи дослідження. Для виявлення кислот гідроксикоричних використовували спиртово-водну витяжку. Реакція з 1 % розчином ферум (ІІІ) хлориду (поява зелено-сірого забарвлення) свідчила про наявність у досліджуваній витяжці сполук фенольної природи. Кількісне визначення кислот гідроксикоричних у досліджуваних об’єктах ґрунтується на спектрофотометричному методі. Якісний склад і кількісний вміст індивідуальних кислот гідроксикоричних у траві та підземних органах бедринцю ломикаменевого досліджували методом високоефективної рідинної хроматографії на хроматографі Agilent 1200 3 D LC System Technologies (США). &#x0D; Результати й обговорення. Кількісний вміст суми кислот гідроксикоричних у траві бедринцю ломикаменевого становив (4,68±0,05) %, в підземних органах – (1,52±0,03) %. Методом високоефективної рідинної хроматографії в досліджуваних об’єктах рослини виявлено й ідентифіковано кислоти хлорогенову і розмаринову та встановлено їх кількісний вміст. У траві й підземних органах бедринцю ломикаменевого в основному домінує кислота хлорогенова, вміст якої становив 3,13 і 0,11 % відповідно. У траві рослини міститься 0,34 % кислоти розмаринової.&#x0D; Висновки. Встановлено наявність і визначено кількісний вміст кислот гідроксикоричних у траві та підземних органах бедринцю ломикаменевого, який становив (4,68±0,05) і (1,52±0,03) % відповідно. Методом високоефективної рідинної хроматографії в досліджуваній сировині рослини виявлено індивідуальні кислоти гідроксикоричні – хлорогенову і розмаринову, визначено їх кількісний вміст. У траві й підземних органах бедринцю ломикаменевого домінує кислота хлорогенова, вміст якої становив 3,13 і 0,34 % відповідно, тому її можна рекомендувати для стандартизації сировини.