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1

Transfer of TLC screening methods to quantitative HPTLC–densitometry methods for pharmaceutical products containing amlodipine besylate, cefpodoxime proxetil, cetirizine 2HCl, diclofenac sodium, efavirenz, mefenamic acid, and atovaquone + proguanil HCl

Zeng B., Gu Y., Sherma J.

Acta Chromatographica

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2019

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Vol. 31, no. 4

246--249

EN

Transfer of seven thin-layer chromatography (TLC) Global Pharma Health Fund E.V. Minilab protocols for screening counterfeit pharmaceutical products in the field to quantitative high-performance TLC (HPTLC)–densitometry methods was performed using a model process published previously. The developed and validated methods for tablets containing amlodipine besylate, cefpodoxime proxetil, cetirizine 2HCl, diclofenac sodium, efavirenz, mefenamic acid, and atovaquone + proguanil HCl involved the use of only relatively inexpensive and nontoxic solvents, Merck KGaA Premium Purity HPTLC silica gel 60 F254 plates, semi-automated sample and standard solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification. In addition, previously transferred HPTLC–densitometry methods for azithromycin and for cephalexin were used to analyze a new product of each drug to demonstrate the applicability of the methods.

2

Development of quantitative HPTLC–Densitometry methods for the analysis of amiodarone HCl, carvedilol, doxylamine succinate, magnesium salicylate, metoprolol succinate, nebivolol HCl, and salicylamide using a model process developed earlier for the transfer of TLC screening methods

Nguyen K., Sherma J.

Acta Chromatographica

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2018

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Vol. 30, no. 4

264--268

EN

A model process, previously developed in a series of studies, allows for the transfer of thin-layer chromatography (TLC) methods for qualitative screening of counterfeit drug products published in the Global Pharma Health Fund (GPHF) Minilab manual and US Food and Drug Administration (FDA) Compendium of Unofficial Methods for Screening of Pharmaceuticals by TLC to quantitative high-performance TLC (HPTLC)–densitometry methods. This article describes HPTLC–densitometry methods developed and validated according to this model process for pharmaceutical products of amiodarone HCl, carvedilol, doxylamine succinate, magnesium salicylate, metoprolol succinate, nebivolol HCl, and salicylamide, for which qualitative screening methods have not been published in the Minilab manual or FDA Compendium. These methods use relatively inexpensive and nontoxic “green solvents” for sample and standard solution and mobile phase preparation, Merck Premium Purity silica gel 60 F254 plates, automated standard and sample solution bandwise application, and automated densitometry for the assessment of peak purity and identity and quantification. Corresponding to the quantitative HPTLC–densitometry methods, qualitative TLC screening methods for these drug products were developed and posted online with open access as supplements to the FDA Compendium.

3

Qualitative and quantitative determination of main alkaloids of Chelidonium majus L. using thin-layer chromatographic-densitometric method

Bogucka-Kocka A., Zalewski D.

Acta Chromatographica

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2017

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Vol. 29, no. 3

385--397

EN

We present a new simple thin-layer chromatographic method designed for determination of the main alkaloids of Chelidonium majus L. In this study, we used roots and herb of the plant collected in spring and autumn. The alkaloid fractions were prepared according to modified pharmacopeial procedure [1]. In our method, we performed two-step elution onto silica gel plates. The first eluent consisted of chloroform, methanol, and water mixed with 70:30:4 proportion. The second eluent comprised of toluene, ethyl acetate, and methanol with 83:15:2 proportion. The described thin-layer chromatography (TLC) system allows qualitative and quantitative determination of the following alkaloids: sanguinarine, chelerythrine, chelidonine, coptisine, and berberine. For determination of protopine, eluent with n-buthanol, acetic acid, and water in 15:1.5:4 proportion was investigated.The dominant alkaloids observed in studied fractions were coptisine (1027.096 ± 13.367–287.474 ± 3.069 mg/100 g dry matter ± sdv) and chelidonine (1780.667 ± 263.522– 115.929 ± 14.694 mg/100 g dry matter ± sdv). The alkaloid detected in the least amount was chelerythrine (30.74 ± 7.526–1.143 ± 0.0651 mg/100 g dry matter ± sdv). The highest total amount of all alkaloids was determined in the fractions obtained from herbs in spring, and the lowest amount was detected in herbs autumn.Additionally, we compared amounts of studied alkaloids in different parts of plants (aerial parts and roots). The plants were collected in spring and autumn. Authors concluded that the presented method can be used as a valuable tool for screening studies on C. majus L.

4

Development of quantitative HPTLC–densitometry methods following a model approach for transfer of TLC screening methods for pharmaceutical products of cefixime, cefuroxime axetil, cephalexin⋅H2O, ciprofloxacin HCl, levofloxacin, and metronidazole

Zhang D., Armour E., Sherma J.

Acta Chromatographica

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2017

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Vol. 29, no. 4

484--486

EN

Transfer of six thin-layer chromatography (TLC) Global Pharma Health Fund Minilab kit protocols for detecting fake or markedly substandard drugs in pharmaceutical products in the field to quantitative high-performance TLC (HPTLC)–densitometry methods was carried out using a model process published earlier. The developed and validated methods for tablets or capsules containing cefixime, cefuroxime axetil, cephalexin•H2O, ciprofloxacin HCl, levofloxacin, and metronidazole involved use of EMD Millipore Premium Purity silica gel 60 F254 plates, automated sample and standard solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification.

5

Techniki chromatograficzne i pokrewne w farmakopeach polskich

Bilek M., Namieśnik J.

Analityka : nauka i praktyka

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2016

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nr 1

56--58

PL

Podstawowym narzędziem analitycznym w farmakopeach polskich pozostaje technika chromatografii cienkowarstowej, przy czym w kolejnych wydaniach obserwuje się stały wzrost znaczenia technik chromatografii gazowej i cieczowej.

6

Use of a model process for transfer of minilab TLC screening methods for quinine sulfate, mefloquine, and dihydroartemisinin—piperaquine phosphate tablets to quantitative HPTLC—densitometry methods

Strock J., Nguyen M., Sherma J.

Acta Chromatographica

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2016

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Vol. 28, no. 3

363--372

EN

Transfer of four thin-layer chromatography (TLC) Global Pharma Health Fund Minilab mobile kit protocols for detecting fake pharmaceutical products to quantitative high-performance TLC (HPTLC)—densitometry methods was carried out using a model process published earlier. The developed and validated methods were for the drugs quinine sulfate, mefloquine, dihydroartemisinin, and piperaquine phosphate. EMD Millipore Premium Purity silica gel 60 F254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 for detection, identification, and quantification were used. Sample peak identity and purity validation were carried out by spectral comparison checks available in the winCATS software, and accuracy was estimated by the standard addition approach. HPTLC gives better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Minilab TLC procedures to support regulatory compliance actions. These new methods should be fully validated according to International Conference on Harmonization guidelines or by interlaboratory studies if required by their applications. In addition, a previously reported transferred simultaneous HPTLC–densitometry method for lumefantrine and artemether was used to analyze a new combination tablet to demonstrate its applicability.

7

Determination of growth-phase dependent influences exerted by prions on yeast lipid content using HPTLC—densitometry

Bui Q., Sherma J., Fried B., Hines K.

Acta Chromatographica

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2016

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Vol. 28, no. 3

373--385

EN

Prions of the baker’s yeast Saccharomyces cerevisiae allow for the inheritance of complex traits based solely on the acquisition of cytoplasmic protein aggregates and confer distinctive phenotypes to the cells which harbor them, creating heterogeneity within an otherwise clonal cell population. These phenotypes typically arise from a loss-of-function of the prion-forming protein that is unable to perform its normal cellular function( s) while sequestered in prion amyloid aggregates, but the specific biochemical consequences of prion infection are poorly understood. To begin to address this issue, we initiated a direct investigation into the potential control that yeast prions exert over fungal lipid content by utilizing the prions [URE3] and [PSI+], the first two prions discovered in yeast. We utilized silica gel high-performance thin-layer chromatography (HPTLC)—densitometry to conduct pair-wise quantifications of the relative levels of free sterols, free fatty acids, and triacylglycerols [petroleum ether—diethyl ether—acetic acid (80:20:1) mobile phase, phosphomolybdic acid (PMA) detection reagent]; steryl esters and squalene (hexane—petroleum ether—diethyl ether—acetic acid (50:20;5:1), PMA]; and phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol (chloroform– diethyl ether—acetic acid (65:25:4.5), cupric sulfate—phosphoric acid) in otherwise clonal prion-infected ([PSI+] or [URE3]) and prion-free ([psi−] or [ure-o]) cells in two growth phases: log-phase and stationary phase. Our analysis revealed multiple statistically significant differences (p < 0.00625) between prion-infected and prion-free cells. Interestingly, prion-induced changes varied dramatically by growth phase, indicating that prions exert differential influences on cell physiology between log and stationary growth. Further experimental replication and extension of the analysis to other prions is expected to resolve additional physiological effects of prion infection. This investigation demonstrates that HPTLC—densitometry is an effective method for studying prion-induced alterations in lipid content in yeast.

8

Zanieczyszczenia biologiczne elewacji

Ksit B., Horbik D.

Builder

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2015

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R.19, nr 4

80--83

EN

The article presents the cause of fungal contamination on the facades and the most common methods for the determination of fungi on the surface of the material. In order to analyze the substrate and to obtain full information about the presence of the fungus is advisable to use thin-layer chromatography with a bioluminescence detection. Algae, fungi and mosses during its growth and exhibit bioluminescence inducted luminescence light.

PL

W artykule przedstawiono przyczyny powstawania zmian mikologicznych na elewacjach oraz najczęściej występujące metody oznaczania grzybów pleśniowych na powierzchni materiału. W celu analizy podłoża i uzyskania pełnej informacji o obecności grzyba wskazane jest zastosowanie chromatografii cienkowarstwowej z detekcją bioluminescencyjną. Glony, grzyby i mchy w trakcie swojego wzrostu wykazują bioluminescencję i luminescencję indukowaną światłem.

9

TLC—Densitometric Determination of Sulfasalazine and Its Possible Impurities in Pharmaceutical Preparations

Kwiecień A., Piątek K., Żmudzki P., Krzek J.

Acta Chromatographica

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2015

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Vol. 27, no. 4

623--635

EN

A simple, selective, and sensitive thin-layer chromatographic—densitometric method has been developed for the determination of sulfasalazine besides its possible impurities in pharmaceutical preparations. The mobile phase was composed of ethyl acetate—methanol—ammonia 25% 10:7:3 (υ/υ/υ), and the stationary phase was aluminum plates precoated with silica gel 60 F254 that enabled to obtain well resolved peaks of sulfasalazine and its impurities. The developed chromatograms were analyzed densitometrically at λ = 360 nm. RF values and ultraviolet (UV) spectra were used to identify the compounds. The developed method is highly sensitive (limit of detection [LOD] = 17.11 ng spot−1, limit of quantitation [LOQ] = 51.84 ng spot−1), precise (relative standard deviation [RSD] = 1.43%–4.28%), and accurate (RSD = 1.64%–4.27%). The linearity of the method was checked within the range 20–120 ng spot−1. The method was successfully applied for the determination of sulfasalazine in pharmaceutical preparations besides its impurities. The structures of impurities present in the standard substance and in pharmaceutical preparations were established by ultra-performance liquid chromatography—tandem mass spectrometry (UPLC—MS/MS) technique.

10

Retention and separation efficiency of some synthetic oligopeptides in reversed-phase thin-layer chromatography

Gwarda R. Ł., Tomczyszyn A., Misicka A., Dzido T. H.

Acta Chromatographica

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2015

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Vol. 27, no. 1

1--14

EN

Influence of the following variables such as adsorbent type, type and concentration of organic modifier in mobile phase, type and concentration of ion-pairing reagent, or pH of the mobile phase buffer on retention of some synthetic peptides in reversed-phase high-performance thin-layer chromatography systems has been investigated. The investigations have been also focused on influence of the variables mentioned on solute zone shape regarding optimization of their separation. Remarks about solute retention mechanism have been also provided.

11

Transfer of TLC screening methods designed for use in developing countries to quantitative HPTLC-densitometry methods for diazepam and amodiaquine tablets

Popovic N., Sherma J.

Acta Chromatographica

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2014

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Vol. 26, no. 4

615--623

EN

Transfer of two rapid thin-layer chromatography (TLC) screening methods used to detect markedly substandard and fake pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods is demonstrated using a model procedure that was published earlier. These TLC methods for diazepam and amodiaquine are contained in a Compendium of methods by Kenyon and Layloff and a Minilab method manual from Global Pharma Health Fund E.V., respectively, for use in countries with limited resources. Merck HPTLC Premium Purity silica gel 60 F254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 were used for detection, identification, and quantification. Sample peak identity and purity validation were carried out by spectral comparison checks available in the winCATS software. Accuracy was estimated by the standard addition approach with overspotting standard and sample solutions. HPTLC gives better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Compendium and Minilab TLC procedures to support regulatory compliance actions. These new methods can be fully validated according to the International Conference on Harmonization guidelines or by interlaboratory studies if required by their applications.

12

Simultaneous identification and quantitative determination of azithromycin, clarithromycin, roxithromycin, spiramycin and troleandomycin by thin-layer chromatography and densitometry

Kwiecień A., Krzek J., Gądek M.

Acta Chromatographica

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2014

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Vol. 26, no. 4

657--670

EN

The purpose of this work was to develop a TLC-densitometric method for simultaneous identification and quantitative determination of azithromycin, clarithromycin, roxithromycin, spiramycin, and troleandomycin. The method was developed on TLC aluminium plates precoated with silica gel F254 using solvent system izopropanol:n-hexane:ammonia 25% (8:12:3, v/v/v), which gives compact spots for azithromycin (RF = 0.65), clarithromycin (RF = 0.54), roxithromycin (RF = 0.49), spiramycin (RF = 0.22), and troleandomycin (RF = 0.36). Densitometric analysis was carried out at 478 nm after spraying with (1:4, v/v) sulphuric acid:ethanol and heating at 100°C for 5 min. The linear regression analysis data for the calibration plots showed good linear relationship with correlation coefficient higher than 0.99. The method is distinguished by high sensitivity, with limit of detection (LOD) from 0.34 μg/spot for troleandomycin to 0.67 μg/spot for clarithromycin and limit of quantification (LOQ) from 1.02 μg/spot for troleandomycin to 2.04 μg/spot for clarithromycin and a wide linearity range from 2 to 12 μg/spot for spiramycin and 2–15 μg/spot for other antibiotics. The precision of the determination was good; relative standard deviation (RSD) varied in the range from 1.49% to 4.14%.

13

Assessing the efficacies of phenolic compounds in pomegranate juice using thin-layer chromatography

Fakhri E., Petróczi A., Naughton D. P.

Acta Chromatographica

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2014

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Vol. 26, no. 3

563--573

EN

Pomegranates (Punica granatum) have been known for centuries for their healing properties. The phenolic components of pomegranate are believed to be responsible for their antioxidant activities, hence playing a major role in reducing oxidative stress-related disease, such as cardiovascular diseases, cancer, and neurodegenerative diseases. In this study, thin-layer chromatography (TLC) was used to, first, separate and identify the phenolic constituents of pomegranate juice and, second, to assess the antioxidant efficacies of the identified compounds. Different oxidant and hydroxyl radical generating systems (Fe3+, Cu2+, H2O2, Fe2+-H2O2, and Cu2+-H2O2) were used in assessing the efficacies of phenolic compounds found in pomegranate juice. A 10 × 10 cm and 20 × 20 cm sized silica gel 60 F254 TLC plates with toluene-ethyl acetate-formic acid (60:40:10 v/v/v) as a mobile phase were used for the chromatographic separation. Two compounds, ellagic acid and gallic acid, were separated and identified. When pomegranate juice was challenged with the oxidant systems, it was observed that the phenolic compounds slowly disappeared in a concentration- and time-dependent manner. From the results, it was concluded that gallic acid had a higher antioxidant efficacy than ellagic acid. TLC has been applied for the first time to outline the antioxidant profile of pomegranate juice and assess the efficacies of phenolics using different oxidant systems, including redox-active metals and H2O2.

14

Krótki przegląd zastosowań cyklodekstryn dotyczący analiz farmaceutycznych, biomedycznych oraz środowiskowych

Lamparczyk H., Chmielewska A., Zarzycki P. K.

Camera Separatoria

|

2013

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Vol. 5, No. 1

27--34

PL

Przedstawiona praca jest ostatnim projektem naukowym nad jakim pracował Profesor Henryk Lamparczyk, który przedwcześnie zmarł 16 listopada 2012 roku w wieku 65 lat. Przeglądowa praca o charakterze dydaktyczno-poglądowym dotyczy zastosowania cyklodekstryn w bioanalityce i została napisana w oparciu o prace opublikowane przez Profesora i współpracowników. Niniejsza wersja bazuje na artykule pt. “Natural cyclodextrins: development in theory, chromatography and pharmacy, A. Chmielewska, H. Lamparczyk;” opublikowanej w materiałach Supramolecular Chemistry and Advanced Materials. Wojciech Macyk & Konrad Szaciłowski, Editors, Kraków Jagielonian University 2007, pages 131-136 i jest rozszerzona o wiadomości przedstawione w najnowszych publikacjach dotyczących zastosowania cyklodekstryn w HPLC, głównie do oznaczeń sterydów i analiz przesiewowych próbek środowiskowych.

EN

This is the last research project of Professor Henryk Lamparczyk that prematurely passed away at age 65. In his intention it was to prepare a demonstrative review paper concerning application of cyclodextrins in bioanalysis, based on his and co-worker contributions to the field of supramolecular chemistry. This version of paper is based on the manuscript entitled “Natural cyclodextrins: development in theory, chromatography and pharmacy, A. Chmielewska, H. Lamparczyk;” that was published in Supramolecular Chemistry and Advanced Materials. Wojciech Macyk & Konrad Szaciłowski, Editors, Kraków Jagielonian University 2007, pages 131-136 and now is extended for the latest papers concerning HPLC application of cyclodextrins for steroids analysis and environmental samples screening. The main tools applied in described investigations were various chromatographic techniques such as gas chromatography (GC), high performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). Topics such as structure-retention relationships, equilibrium constants between cyclodextrins (CDs) and guest molecules, thermodynamics and CDs separations were discussed. Additionally few examples of practical applications of CDs in pharmacy as well as biomedical and environmental analysis are given.

15

Szybka ocena biodegradacji estriolu w oparciu o metodę Ternesa oraz mikrochromatografię cienkowarstwową (mikro-TLC) w warunkach kontrolowanej temperatury

Włodarczyk E., Zarzycki P. K.

Pomiary Automatyka Kontrola

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2011

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R. 57, nr 6

620-623

PL

Spośród różnych systemów oczyszczania ścieków w krajach europejskich najczęściej stosuje się technologie wykorzystującą osad czynny. Jednak proces ten może nie być w pełni efektywny w przypadku usuwania substancji zaliczanych do grupy tzw. modulatorów hormonalnych (endocrine disrupting compounds, EDCs), w tym naturalnych estrogenów. Aby poprawić skuteczność pracy oczyszczalni, należy poznać czynniki odpowiedzialne za prawidłowy przebieg procesu technologicznego. Dlatego prace badawcze przeprowadzane na skalę laboratoryjną pomagają określić warunki i mechanizmy biodegradacji wybranych związków. W niniejszej pracy do oceny tempa rozkładu estriolu przez mikroorganizmy osadu czynnego w warunkach laboratoryjnych, zastosowano metodę opracowaną przez Ternesa i in. (1999). Jej skuteczność oceniano poprzez rozdzielenie estriolu i produktu biodegradacji za pomocą mikrochromatografii cienkowarstwowej z użyciem płytek typu RP18W. Detekcję analitów przeprowadzono za pomocą wybarwiania mikrochromatogramów kwasem fosforo-molibdenowym.

EN

Wastewater treatment plant effluents are the main sources of micropollutants like endocrine disrupting compounds (EDCs) that are present in the aquatic environment. Raw sewages treatment technology based on activated sludge is presently most commonly used in Europe. Unfortunately, a number of studies have revealed that this method seems to be non-effective to remove of estrogenic compounds including natural estrogens.The aim of this study was to apply the method invented by Ternes (et al. 1999) to estrogens biodegradation involving activated sludge material and target component quantification using the micro-TLC method combined with PMA detection of low-molecular target compounds. Activated sludge samples were taken from the munic-ipal sewage treatment plant Jamno near Koszalin. The aerobic batch experiments with real sludge samples (Fig. 1) have revealed that estriol can be biodegraded relatively slowly toward one degradation product, which seems to be less polar than estrogen investigated. Particularly, it has been found that after 72h around 50% of the initial steroid level has still been detected (Fig. 2). This confirms the authors' earlier observation concerning biodegradation product analysis via temperature-dependent inclusion chromatography (HPLC) involving beta-cyclodextrin as the inclusion agent. The laboratory biodegradation test with micro-TLC determination of target components has confirmed that microorganisms are not able to efficiently decompose estriol mole-cules within 24 hours period, which corresponds to the typical retention time of wastewater in treatment plant Jamno. The described protocol can be successfully applied to fast screening and fingerprinting of wide range of estrogens and related low-molecular mass active substances from complex environmental samples. This approach is non-expensive and requires basic analytical equipment, because separation process involves commercially available typical HPTLC plates. Moreover, data acquisition and quantification process can be simply performed using common office scanners or digital cameras.

16

Analiza substancji biologicznie aktywnych

Gierak A., Skorupa A., Grabowska E., Łazarska I.

LAB Laboratoria, Aparatura, Badania

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2011

|

R. 16, nr 6

16-22

PL

W pracy opisano wykorzystanie barwy rozdzielanych substancji w analizie chemicznej, wykonywanej metoda chromatografii cienkowarstwowej TLC. Analiza substancji metodą TLC jest stosunkowo prosta i nie wymaga skomplikowanej aparatury, natomiast jej słabą stroną jest detekcja i identyfikacja rozdzielonych substancji. W związku z powyższym autorzy pracy zwrócili szczególną uwagę na metody detekcji substancji na płytkach chromatograficznych, zwłaszcza na różnego rodzaju reakcje z rozdzielonymi, bezbarwnymi substancjami, które zarówno umożliwiają ich wykrycie, jak i możliwość identyfikacji (analizę jakościową) na podstawie ich charakterystycznej barwy. Z drugiej strony intensywność zabarwienia otrzymanych pasm chromatograficznych na płytkach TLC maja bezpośredni związek z czułością i oznaczalnością tych substancji, gdyż im bardziej intensywną barwę posiada plamka rozdzielanej substancji, tym intensywnej absorbuje kwanty promieniowania UV-VIS a tym samym umożliwia detekcje tych składników na niższym poziomie stężeń.

17

Evaluation of sample application techniques, stationary and mobile phases, and detection reagents for HPTLC — Densitometry analysis of glucose in fecal samples of mice infected with Echinostoma caproni (Trematoda)

Cicchi M., O’sullivan C. O, Fried B., Sherma J.

Acta Chromatographica

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2011

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Vol. 23, no. 2

295--305

EN

Seven different thin-layer chromatography stationary phases, one additional stationary layer pretreatment, eight mobile phases, two spotting techniques, and three detection reagents were evaluated for the determination of glucose in mouse fecal samples. Quantitative analysis was performed by slit-scanning densitometry. The optimal system was found to be Merck silica gel HPTLC plates with a concentrating zone developed with 1-butanol-glacial acetic acid-diethyl ether-deionized water 27:18:5:3. α-Naphthol-sulphuric acid detection reagent was found to give the best quantitative results, while the naphthoresorcinol reagent was the most useful for qualitative analysis. Semiautomatic application of samples with a CAMAG Linomat was found to give more compact bands and better separations than manual application. Using this system, quantification of glucose was achieved in mouse fecal samples. The amounts of glucose in the fecal samples of BALB/c mice infected with the intestinal trematode E. caproni were compared to control samples of uninfected mice. On the third and tenth days of postinfection, it was determined that the amount of glucose in the infected fecal samples was significantly greater than in the control samples. This indicates that metabolic profiling of glucose using TLC is possible in the mouse model and that TLC may potentially be used to test for the presence of E. caproni in humans.

18

Effect of mobile phase composition on the overall elution process in thin-layer chromatography

Prus W., Kaczmarski K.

Acta Chromatographica

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2011

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Vol. 23, no. 4

681--692

EN

Phenylacetone was chromatographed on alumina with mixture of toluene and 1,4-dioxane as a mobile phase in a thin-layer chromatography (TLC) system. All the chromatograms were scanned with a densitometer. It was found that for such a binary mobile phase, there is a range of stronger component concentration that gives both peaks of Gaussian shape and triangle-like shape as well. Non-Gaussian peaks of phenylacetone chromatographed on alumina with a mixture of toluene and 1,4-dioxane were observed in the case of relatively low concentration of the latter in the mobile phase. Appropriate model describing the observed retention process is suggested.

19

A validated stability-indicating method for simultaneous analysis of mevastatin and pravastatin in fermentation broth during bioconversion by Actinomadura macra

Ahmad A., Panda B. P, Mujeeb M

Acta Chromatographica

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2011

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Vol. 23, no. 1

121--131

EN

A simple, accurate, selective, precise, economical, and stability-indicating high-performance thin-layer chromatographic method for simultaneous analysis of mevastatin and pravastatin in fermentation broth has been established and validated. Compounds were separated on aluminium foil TLC plates precoated with silica gel 60F254; the mobile phase was toluene-ethyl acetate-formic acid 3:2:1 (v/v), which gave compact bands of mevastatin and pravastatin (RF 0.48 ± 0.02 and 0.31 ± 0.02, respectively). Detection at 237 nm resulted in r = 0.992 and 0.995 for mevastatin and r = 0.995 and 0.994 for pravastatin, for peak height and peak area, respectively. The limits of detection and quantification for mevastatin were 20.1 and 60.8 ng per band, and for pravastatin 19.2 and 58.3 ng per band, respectively. The method enabled effective quantification of mevastatin and pravastatin in the fermentation broth of Actinomadura macra and can therefore be used as a stability-indicating method for routine analysis of these compounds during bioconversion.

20

A simple TLC-MALDI method to monitor oxidation products of phosphatidylcholines and -ethanolamines

Bischoff A, Eibisch M, Fuchs B, Süss R, Schürenberg M, Suckau D, Schiller J.

Acta Chromatographica

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2011

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Vol. 23, no. 2

365--375

EN

The analysis of lipid-phospholipid oxidation products is of primary importance. Although there are established HPLC and LC-MS techniques, it is shown here for the first time that the combination of matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and TLC represents a sensitive, fast, and convenient alternative. A mixture of 1-palmitoyl-2-linoleoyl-sn-phosphatidylcholine (PLPC) and -ethanolamine (PLPE) was oxidized under the influence of atmospheric oxygen and characterized by direct positive ion MALDI-TOF MS as well as combined TLC-MALDI. It is shown that much more detailed information — particularly related to the oxidation products of PLPE that have so far been scarcely investigated — can be obtained by TLC-MALDI. However, it is also shown that further methodological improvements are necessary to make this method generally applicable to complex lipid mixtures.