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Irena Kralj Cigić
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1001 Ljubljana, Slovenia

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Journal article
Published: 17 June 2021 in Polymers
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Determination of cellulose degree of polymerization (DP) is one of the most commonly used methods in paper degradation studies, performed either by a standardized method using viscometry (as average degree of polymerization (DPv)) or size-exclusion chromatography (SEC) (as weight average molecular mass (Mw)). Due to the insolubility of papers with high lignin content in cupriethylenediamine (CED), such as groundwood papers, viscometric determination is not possible; therefore, pretreatment is required to allow subsequent dissolution of the papers. In this study, the pretreatment of historical papers containing groundwood with sodium chlorite in acetic acid was investigated, which enables dissolution of the paper samples in CED and determination of the cellulose average degree of polymerization by viscometry (DPv). Kappa number was determined to estimate the lignin content in the papers. The suitability of SEC UV-VIS analysis for determination of Mw in papers with high lignin content had been verified before it was used as a comparative method for viscometry. Using SEC, changes in the weight average molecular mass (Mw) of cellulose tricarbanilate (CTC) derivative during delignification were evaluated. The results indicate that no significant depolymerization occurred in the selected samples under the studied delignification conditions, which was additionally confirmed with determination of monosaccharides by ion chromatography. The results of the Mw determinations by SEC and DPv by viscometry are in good correlation, justifying the use of viscometry after chlorite/acetic acid pretreatment to determine the cellulose average degree of polymerization in historical papers with high lignin content.

ACS Style

Jasna Malešič; Ida Kraševec; Irena Kralj Cigić. Determination of Cellulose Degree of Polymerization in Historical Papers with High Lignin Content. Polymers 2021, 13, 1990 .

AMA Style

Jasna Malešič, Ida Kraševec, Irena Kralj Cigić. Determination of Cellulose Degree of Polymerization in Historical Papers with High Lignin Content. Polymers. 2021; 13 (12):1990.

Chicago/Turabian Style

Jasna Malešič; Ida Kraševec; Irena Kralj Cigić. 2021. "Determination of Cellulose Degree of Polymerization in Historical Papers with High Lignin Content." Polymers 13, no. 12: 1990.

Journal article
Published: 27 March 2021 in Polymers
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Wood is a natural polymeric material that is an important constituent of many heritage collections. Because of its susceptibility to biodegradation, it is often chemically treated with substances that can be harmful to human health. One of the most widely used wood preservatives was pentachlorophenol (PCP), which is still present in museum objects today, although its use has been restricted for about forty years. The development of non-destructive methods for its determination, suitable for the analysis of valuable objects, is therefore of great importance. In this work, two non-destructive solid-phase microextraction (SPME) methods were developed and optimized, using either headspace or contact mode. They were compared with a destructive solvent extraction method and found to be suitable for quantification in the range of 7.5 to 75 mg PCP/kg wood at room temperature. The developed semi-quantitative methods were applied in the wooden furniture depot of National Museum of Slovenia. PCP was detected inside two furniture objects using headspace mode. The pesticide lindane was also detected in one object. The indoor air of the depot with furniture was also sampled with HS SPME, and traces of PCP were found. According to the results, SPME methods are suitable for the detection of PCP residues in museum objects and in the environment.

ACS Style

Ida Kraševec; Nataša Nemeček; Maja Lozar Štamcar; Irena Kralj Cigić; Helena Prosen. Non-Destructive Detection of Pentachlorophenol Residues in Historical Wooden Objects. Polymers 2021, 13, 1052 .

AMA Style

Ida Kraševec, Nataša Nemeček, Maja Lozar Štamcar, Irena Kralj Cigić, Helena Prosen. Non-Destructive Detection of Pentachlorophenol Residues in Historical Wooden Objects. Polymers. 2021; 13 (7):1052.

Chicago/Turabian Style

Ida Kraševec; Nataša Nemeček; Maja Lozar Štamcar; Irena Kralj Cigić; Helena Prosen. 2021. "Non-Destructive Detection of Pentachlorophenol Residues in Historical Wooden Objects." Polymers 13, no. 7: 1052.

Journal article
Published: 15 February 2021 in Heritage Science
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Acetic acid and formic acid are volatile pollutants leading to degradation of some heritage materials. They are usually determined in museum environments with various types of passive samplers. In this work, SKC UMEx 200 passive samplers, originally intended for sampling of $$\hbox {NO}_{2}$$ NO 2 and $$\hbox {SO}_{2}$$ SO 2 , have been validated for sampling of these organic acids. The sampling rates, extraction efficiency, loss through reverse diffusion or during storage, capacity, and detection limits were determined for both acids. For laboratory exposure, a known concentration of both acids was prepared in a flow-through reactor system at controlled temperature and humidity, the samplers were extracted, followed by analysis using ion chromatography. The sampling rates were determined to be 16.7 ml/min for acetic and 17.7 ml/min for formic acid and the detection limits for 7-day exposure were determined to be $${2.1}\,{\upmu }{\rm g/m}^3$$ 2.1 μ g / m 3 for acetic and $${1.9}\,{\upmu }\hbox {g/m}^3$$ 1.9 μ g/m 3 for formic acid. The validated method was finally used for sampling of air in two case studies at the National Museum of Slovenia, where the concentrations in the range of 2– $${54}\,{\upmu }\hbox {g/m}^3$$ 54 μ g/m 3 were determined.

ACS Style

Ida Kraševec; Eva Menart; Matija Strlič; Irena Kralj Cigić. Validation of passive samplers for monitoring of acetic and formic acid in museum environments. Heritage Science 2021, 9, 1 -10.

AMA Style

Ida Kraševec, Eva Menart, Matija Strlič, Irena Kralj Cigić. Validation of passive samplers for monitoring of acetic and formic acid in museum environments. Heritage Science. 2021; 9 (1):1-10.

Chicago/Turabian Style

Ida Kraševec; Eva Menart; Matija Strlič; Irena Kralj Cigić. 2021. "Validation of passive samplers for monitoring of acetic and formic acid in museum environments." Heritage Science 9, no. 1: 1-10.

Journal article
Published: 26 November 2020 in Heritage Science
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In this study, a painted beehive panel from the collection of the Slovene Ethnographic Museum was examined with respect to its material composition with the aim to reveal the painting technique. Due to the state of degradation due to outdoor weathering (UV irradiation, rainfall, extreme temperature and humidity fluctuations), as well as past conservation interventions, the object represented a complex analytical challenge. We aimed for non-invasive techniques (FTIR in reflection mode, Raman spectroscopy and hyperspectral imaging in the range of 400–2500 nm); however, in order to explore paint layers, cross-sections were also analysed using Raman spectroscopy. FTIR spectroscopy in transmission mode and gas chromatography coupled to mass spectrometry were also used on sample fragments. Various original materials were identified such as pigments and binders. The surface coating applied during conservation interventions was also characterised. Additionally, organic compounds were found (oxalate, carboxylate), representing transformation products. The potential use of Prussian blue as a background paint layer is discussed.

ACS Style

Klara Retko; Maša Kavčič; Lea Legan; Polonca Ropret; Bojana Rogelj Škafar; Yingwang Gao; John Gilchrist; Matija Strlič; Irena Kralj Cigić. Material characterisation of a painted beehive panel by advanced spectroscopic and chromatographic techniques in combination with hyperspectral imaging. Heritage Science 2020, 8, 1 -13.

AMA Style

Klara Retko, Maša Kavčič, Lea Legan, Polonca Ropret, Bojana Rogelj Škafar, Yingwang Gao, John Gilchrist, Matija Strlič, Irena Kralj Cigić. Material characterisation of a painted beehive panel by advanced spectroscopic and chromatographic techniques in combination with hyperspectral imaging. Heritage Science. 2020; 8 (1):1-13.

Chicago/Turabian Style

Klara Retko; Maša Kavčič; Lea Legan; Polonca Ropret; Bojana Rogelj Škafar; Yingwang Gao; John Gilchrist; Matija Strlič; Irena Kralj Cigić. 2020. "Material characterisation of a painted beehive panel by advanced spectroscopic and chromatographic techniques in combination with hyperspectral imaging." Heritage Science 8, no. 1: 1-13.

Preprint content
Published: 19 November 2020
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Acetic acid and formic acid are volatile pollutants leading to degradation of some heritage materials. They are usually determined in museum environments with various types of passive samplers. In this work, SKC UMEx 200 passive samplers, originally intended for sampling of NO2 and SO2, have been validated for sampling of these organic acids. The sampling rates, extraction efficiency, loss through reverse diffusion or during storage, capacity, and detection limits were determined for both acids. For laboratory exposure, a known concentration of both acids was prepared in a flow-through reactor system at controlled temperature and humidity, the samplers were extracted, followed by analysis using ion chromatography. The sampling rates were determined to be 16.7 ml/min for acetic and 17.7 ml/min for formic acid and the detection limits for 7-day exposure were determined to be 2.1 µg/m3 for acetic and 1.9 µg/m3 for formic acid. The validated method was finally used for sampling of air in two case studies at the National Museum of Slovenia, where the concentrations in the range of 2-54 µg/m3 were determined.

ACS Style

Ida Kraševec; Eva Menart; Matija Strlič; Irena Kralj Cigić. Validation of Passive Samplers for Monitoring of Acetic and Formic Acid in Museum Environments. 2020, 1 .

AMA Style

Ida Kraševec, Eva Menart, Matija Strlič, Irena Kralj Cigić. Validation of Passive Samplers for Monitoring of Acetic and Formic Acid in Museum Environments. . 2020; ():1.

Chicago/Turabian Style

Ida Kraševec; Eva Menart; Matija Strlič; Irena Kralj Cigić. 2020. "Validation of Passive Samplers for Monitoring of Acetic and Formic Acid in Museum Environments." , no. : 1.

Journal article
Published: 08 October 2020 in Electrochimica Acta
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The HPLC method including derivatisation was used for the determination of polysulfide species concentration during the operation of lithium-sulfur battery cells. A comparison was made between a glyme based electrolyte, which exhibits high polysulfide solubility, and a fluorinated ether based electrolyte, which was proposed to reduce the dissolution and diffusion of polysulfides. A separate analysis was conducted on porous carbon cathodes and separators obtained from cycled battery cells. The determination of the species concentration trends allowed a deeper understanding of the differences in battery cell operating mechanism. We have determined that polysulfide species are formed in similar concentrations in both examined electrolytes, but they remain trapped in the cathode pores in the fluorinated ether based electrolyte lithium-sulfur battery cells. The polysulfide concentration in the separators of the fluorinated ether cells was below the limit of detection, which indicates that the solubilities of polysulfides in the fluorinated electrolyte are below 50 µM. This results in absence of disproportionation or coproportionation reactions between the polysulfide species in solution. This different mechanism influences the change in length and potential of the voltage plateaus of the battery cells during galvanostatic cycling.

ACS Style

Urban Košir; Irena Kralj Cigić; Jernej Markelj; Sara Drvarič Talian; Robert Dominko. Polysulfide species in various electrolytes of Li-S batteries – a chromatographic investigation. Electrochimica Acta 2020, 363, 137227 .

AMA Style

Urban Košir, Irena Kralj Cigić, Jernej Markelj, Sara Drvarič Talian, Robert Dominko. Polysulfide species in various electrolytes of Li-S batteries – a chromatographic investigation. Electrochimica Acta. 2020; 363 ():137227.

Chicago/Turabian Style

Urban Košir; Irena Kralj Cigić; Jernej Markelj; Sara Drvarič Talian; Robert Dominko. 2020. "Polysulfide species in various electrolytes of Li-S batteries – a chromatographic investigation." Electrochimica Acta 363, no. : 137227.

Preprint content
Published: 16 July 2020
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In this study, a painted beehive panel from the collection of Slovene Ethnographic Museum was examined with respect to its material composition with the aim to reveal the painting technique. Due to the state of degradation due to outdoor weathering (UV irradiation, rainfall, extreme temperature and humidity fluctuations), as well as past conservation interventions, the object represented a complex analytical challenge. We aimed for non-invasive techniques (FTIR in reflection mode, Raman spectroscopy and hyperspectral imaging in the range of 400 to 2500 nm), however in order to explore paint layers, cross-sections were also analysed using Raman spectroscopy. FTIR spectroscopy in transmission mode and gas chromatography coupled to mass spectrometry were also used on sample fragments. Various original materials were identified such as pigments and binders. The surface coating applied during restoration interventions was also characterised. Additionally, organic compounds (oxalate, carboxylate), representing transformation products, were found. The potential use of Prussian blue as a background paint layer is discussed.

ACS Style

Klara Retko; Maša Kavčič; Lea Legan; Polonca Ropret; Bojana Rogelj Škafar; Yingwang Gao; John Gilchrist; Matija Strlič; Irena Kralj Cigić. Material characterisation of a painted beehive panel by hyperspectral imaging in combination with advanced spectroscopic and chromatographic techniques. 2020, 1 .

AMA Style

Klara Retko, Maša Kavčič, Lea Legan, Polonca Ropret, Bojana Rogelj Škafar, Yingwang Gao, John Gilchrist, Matija Strlič, Irena Kralj Cigić. Material characterisation of a painted beehive panel by hyperspectral imaging in combination with advanced spectroscopic and chromatographic techniques. . 2020; ():1.

Chicago/Turabian Style

Klara Retko; Maša Kavčič; Lea Legan; Polonca Ropret; Bojana Rogelj Škafar; Yingwang Gao; John Gilchrist; Matija Strlič; Irena Kralj Cigić. 2020. "Material characterisation of a painted beehive panel by hyperspectral imaging in combination with advanced spectroscopic and chromatographic techniques." , no. : 1.

Original research
Published: 14 July 2020 in Cellulose
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A database of historic paper properties was developed using 729 samples of European origin (1350–1990), analysed for acidity, degree or polymerisation (DP), molecular weight of cellulose, grammage, tensile strength, as well as contents of ash, aluminium, carbonyl groups, rosin, protein, lignin and fibre furnish. Using Spearman’s rank correlation coefficient and principal component analysis, the data were examined with respect to methods of manufacture, as well as chemical stability of paper. Novel patterns emerged related to loss of DP and accumulation of carbonyl groups and acidity with time and the role of lignin and rosin, as well as rate of degradation (k = 10−5 year−1) at room conditions. In-depth understanding of long-term degradation of lignin and rosin is needed to better understand the relationships between composition and degradation of historic paper. This study highlights the importance of mining significant volumes of analytical data, and its variability, obtained from real historic objects.

ACS Style

Matija Strlič; Yun Liu; Dirk Andreas Lichtblau; Gerrit De Bruin; Barry Knight; Thea Winther; Irena Kralj Cigić; Richard G. Brereton. Development and mining of a database of historic European paper properties. Cellulose 2020, 27, 1 -13.

AMA Style

Matija Strlič, Yun Liu, Dirk Andreas Lichtblau, Gerrit De Bruin, Barry Knight, Thea Winther, Irena Kralj Cigić, Richard G. Brereton. Development and mining of a database of historic European paper properties. Cellulose. 2020; 27 (14):1-13.

Chicago/Turabian Style

Matija Strlič; Yun Liu; Dirk Andreas Lichtblau; Gerrit De Bruin; Barry Knight; Thea Winther; Irena Kralj Cigić; Richard G. Brereton. 2020. "Development and mining of a database of historic European paper properties." Cellulose 27, no. 14: 1-13.

Journal article
Published: 01 May 2020 in Foods
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Sprouts and microgreens are a rich source of various bioactive compounds. Seeds of lentil, fenugreek, alfalfa, and daikon radish seeds were germinated and the contents of the polyamines agmatine (AGM), putrescine (PUT), cadaverine (CAD), spermidine (SPD), and spermine (SPM) in ungerminated seeds, sprouts, and microgreens were determined. In general, sprouting led to the accumulation of the total polyamine content. The highest levels of AGM (5392 mg/kg) were found in alfalfa microgreens, PUT (1079 mg/kg) and CAD (3563 mg/kg) in fenugreek sprouts, SPD (579 mg/kg) in lentil microgreens, and SPM (922 mg/kg) in fenugreek microgreens. A large increase in CAD content was observed in all three legume sprouts. Conversely, the nutritionally beneficial polyamines AGM, SPD, and SPM were accumulated in microgreens, while their contents of CAD were significantly lower. In contrast, daikon radish sprouts exhibited a nutritionally better profile of polyamines than the microgreens. Freezing and thawing of legume sprouts resulted in significant degradation of CAD, PUT, and AGM by endogenous diamine oxidases. The enzymatic potential of fenugreek sprouts can be used to degrade exogenous PUT, CAD, and tyramine at pH values above 5.

ACS Style

Irena Kralj Cigić; Sašo Rupnik; Tjaša Rijavec; Nataša Poklar Ulrih; Blaž Cigić. Accumulation of Agmatine, Spermidine, and Spermine in Sprouts and Microgreens of Alfalfa, Fenugreek, Lentil, and Daikon Radish. Foods 2020, 9, 547 .

AMA Style

Irena Kralj Cigić, Sašo Rupnik, Tjaša Rijavec, Nataša Poklar Ulrih, Blaž Cigić. Accumulation of Agmatine, Spermidine, and Spermine in Sprouts and Microgreens of Alfalfa, Fenugreek, Lentil, and Daikon Radish. Foods. 2020; 9 (5):547.

Chicago/Turabian Style

Irena Kralj Cigić; Sašo Rupnik; Tjaša Rijavec; Nataša Poklar Ulrih; Blaž Cigić. 2020. "Accumulation of Agmatine, Spermidine, and Spermine in Sprouts and Microgreens of Alfalfa, Fenugreek, Lentil, and Daikon Radish." Foods 9, no. 5: 547.

Journal article
Published: 18 December 2019 in Acta Chimica Slovenica
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There are several different approaches for LC method development; beside traditional, different software programs for method development and optimization are available. The solvatic retention model of reversed-phase LC was applied for prediction of retention in the gradient elution mode for aripiprazole and its related substances described in European Pharmacopoeia. As some of these compounds have very similar and others quite different chemical structure, their separation is challenge. Prediction was suitable on examined stationary phases (C18, C8 and phenyl-hexyl) with 0.1% phosphoric acid as aqueous mobile phase and acetonitrile or methanol as organic modifier. Predicted retention times take into account structural formulae of compounds and properties of stationary and mobile phases result in average difference of 14-17% compared to experimental ones on phenyl-hexyl stationary phase, where the highest matching was obtained. After utilisation of the retention models with data from one experimental run, the average difference decrease to maximal 7% and after contribution of data from two experimental runs, to maximal 2%. For majority of studied compounds difference between predicted and experimental values on all examined stationary phases is lower than 3%.

ACS Style

Tina Snoj Ekmečič; Irena Kralj Cigic. Application of Solvatic Model for Prediction of Retention at Gradient Elution in Reversed-Phase Liquid Chromatography. Acta Chimica Slovenica 2019, 66, 958 -970.

AMA Style

Tina Snoj Ekmečič, Irena Kralj Cigic. Application of Solvatic Model for Prediction of Retention at Gradient Elution in Reversed-Phase Liquid Chromatography. Acta Chimica Slovenica. 2019; 66 (4):958-970.

Chicago/Turabian Style

Tina Snoj Ekmečič; Irena Kralj Cigic. 2019. "Application of Solvatic Model for Prediction of Retention at Gradient Elution in Reversed-Phase Liquid Chromatography." Acta Chimica Slovenica 66, no. 4: 958-970.

Journal article
Published: 01 October 2019 in Polymer Degradation and Stability
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ACS Style

Gianluca Pastorelli; Shuo Cao; Irena Kralj Cigić; Costanza Cucci; Abdelrazek Elnaggar; Matija Strlič. Development of dose-response functions for historic paper degradation using exposure to natural conditions and multivariate regression. Polymer Degradation and Stability 2019, 168, 1 .

AMA Style

Gianluca Pastorelli, Shuo Cao, Irena Kralj Cigić, Costanza Cucci, Abdelrazek Elnaggar, Matija Strlič. Development of dose-response functions for historic paper degradation using exposure to natural conditions and multivariate regression. Polymer Degradation and Stability. 2019; 168 ():1.

Chicago/Turabian Style

Gianluca Pastorelli; Shuo Cao; Irena Kralj Cigić; Costanza Cucci; Abdelrazek Elnaggar; Matija Strlič. 2019. "Development of dose-response functions for historic paper degradation using exposure to natural conditions and multivariate regression." Polymer Degradation and Stability 168, no. : 1.

Journal article
Published: 16 July 2019 in Heritage Science
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ACS Style

Jasna Malešič; Mariša Kadivec; Matjaž Kunaver; Tina Skalar; Irena Kralj Cigić. Nano calcium carbonate versus nano calcium hydroxide in alcohols as a deacidification medium for lignocellulosic paper. Heritage Science 2019, 7, 1 .

AMA Style

Jasna Malešič, Mariša Kadivec, Matjaž Kunaver, Tina Skalar, Irena Kralj Cigić. Nano calcium carbonate versus nano calcium hydroxide in alcohols as a deacidification medium for lignocellulosic paper. Heritage Science. 2019; 7 (1):1.

Chicago/Turabian Style

Jasna Malešič; Mariša Kadivec; Matjaž Kunaver; Tina Skalar; Irena Kralj Cigić. 2019. "Nano calcium carbonate versus nano calcium hydroxide in alcohols as a deacidification medium for lignocellulosic paper." Heritage Science 7, no. 1: 1.

Original article
Published: 10 June 2019 in Journal of Food Science and Technology
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Six Monascus purpureus (red mould) strains were cultivated on brown rice and millet as substrates. They underwent strain selection for high lovastatin and pigment production, and low citrinin mycotoxin production, with particular reference to potential for millet as substrate. For most of these strains, substrate dry matter loss was 54–60% on rice and 46–48% on millet, although the ‘MOPU GS1’ strain showed 18% and 17% dry matter loss, respectively. ‘MOPU GS1’ was also the only strain with detectable levels of lovastatin (1.3 and 1.6 mg lovastatin/g substrate dry weight [dw], respectively) and citrinin under the limit of detection. In the other strains, citrinin varied from 0.3 to 18.2 mg/g substrate dw. Among the six strains, ‘EBY3’ provided high pigment production when grown on rice, although it produced 1.1 mg citrinin/g substrate dw. Millet showed good potential as an alternative substrate to rice, due to higher lovastatin and lower citrinin production; however, rice was the better substrate for production of M. purpureus pigments.

ACS Style

Ajda Marič; Matej Skočaj; Matevž Likar; Kristina Sepčić; Irena Kralj Cigić; Maja Grundner; Andrej Gregori. Comparison of lovastatin, citrinin and pigment production of different Monascus purpureus strains grown on rice and millet. Journal of Food Science and Technology 2019, 56, 3364 -3373.

AMA Style

Ajda Marič, Matej Skočaj, Matevž Likar, Kristina Sepčić, Irena Kralj Cigić, Maja Grundner, Andrej Gregori. Comparison of lovastatin, citrinin and pigment production of different Monascus purpureus strains grown on rice and millet. Journal of Food Science and Technology. 2019; 56 (7):3364-3373.

Chicago/Turabian Style

Ajda Marič; Matej Skočaj; Matevž Likar; Kristina Sepčić; Irena Kralj Cigić; Maja Grundner; Andrej Gregori. 2019. "Comparison of lovastatin, citrinin and pigment production of different Monascus purpureus strains grown on rice and millet." Journal of Food Science and Technology 56, no. 7: 3364-3373.

Journal article
Published: 07 December 2018 in Acta Pharmaceutica
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Development of safe and effective drugs requires complete impurity evaluation and, therefore, knowledge about the formation and elimination of impurities is necessary. During impurity profiling of a key intermediate during synthesis of candesartan cilexetil (1-(((cyclohexyloxy)carbonyl) oxy)ethyl 1-((2’-(2H-tetrazol-5-yl)-[1,1’-biphenyl]-4-yl) methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate, TCV-116), a novel compound, which had not been reported previously, was observed. Structural elucidation of impurity was achieved by liquid chromatography hyphenated to different high resolution mass analyzers. Based on exact mass measurements and fragmentation pattern, a chloro alkyl carbonate ester analogue of the intermediate was identified. Structure of the impurity was confirmed by mass spectro-metric and NMR analyses of the target substance. Identified impurity could represent a hazard if it is transferred to the final API stage and its presence should be kept below allowed limits. Further investigation could reveal whether bis(1-chloroethyl) carbonate is a precursor to impurity formation. Therefore, synthesis should be regulated so as to minimize impurity production. Analysis of the final product indicated that the amount of impurity did not exceed 50 mg L−1, which represents the detection limit, determined according to the signal/noise ratio.

ACS Style

Ana Testen; Miha Plevnik; Bogdan Štefane; Irena Kralj Cigić. Identification of new process-related impurity in the key intermediate in the synthesis of TCV-116. Acta Pharmaceutica 2018, 69, 63 -74.

AMA Style

Ana Testen, Miha Plevnik, Bogdan Štefane, Irena Kralj Cigić. Identification of new process-related impurity in the key intermediate in the synthesis of TCV-116. Acta Pharmaceutica. 2018; 69 (1):63-74.

Chicago/Turabian Style

Ana Testen; Miha Plevnik; Bogdan Štefane; Irena Kralj Cigić. 2018. "Identification of new process-related impurity in the key intermediate in the synthesis of TCV-116." Acta Pharmaceutica 69, no. 1: 63-74.

Journal article
Published: 16 May 2018 in Soft Matter
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Dynamic light scattering (DLS) and size exclusion chromatography (SEC), that are among the most popular methods for determining polymer nanoparticle (PNP) sizes, essentially depend on the quality of solution.

ACS Style

Artem Badasyan; Andraž Mavrič; Irena Kralj Cigić; Tim Bencik; Matjaž Valant. Polymer nanoparticle sizes from dynamic light scattering and size exclusion chromatography: the case study of polysilanes. Soft Matter 2018, 14, 4735 -4740.

AMA Style

Artem Badasyan, Andraž Mavrič, Irena Kralj Cigić, Tim Bencik, Matjaž Valant. Polymer nanoparticle sizes from dynamic light scattering and size exclusion chromatography: the case study of polysilanes. Soft Matter. 2018; 14 (23):4735-4740.

Chicago/Turabian Style

Artem Badasyan; Andraž Mavrič; Irena Kralj Cigić; Tim Bencik; Matjaž Valant. 2018. "Polymer nanoparticle sizes from dynamic light scattering and size exclusion chromatography: the case study of polysilanes." Soft Matter 14, no. 23: 4735-4740.

Journal article
Published: 01 August 2017 in Polymer Degradation and Stability
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ACS Style

Yun Liu; Irena Kralj Cigić; Matija Strlič. Kinetics of accelerated degradation of historic iron gall ink-containing paper. Polymer Degradation and Stability 2017, 142, 255 -262.

AMA Style

Yun Liu, Irena Kralj Cigić, Matija Strlič. Kinetics of accelerated degradation of historic iron gall ink-containing paper. Polymer Degradation and Stability. 2017; 142 ():255-262.

Chicago/Turabian Style

Yun Liu; Irena Kralj Cigić; Matija Strlič. 2017. "Kinetics of accelerated degradation of historic iron gall ink-containing paper." Polymer Degradation and Stability 142, no. : 255-262.

Research article
Published: 23 June 2016 in The Journal of Physical Chemistry C
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ACS Style

Klementina Pušnik; Mojca Peterlin; Irena Kralj Cigić; Gregor Marolt; Ksenija Kogej; Alenka Mertelj; Sašo Gyergyek; Darko Makovec. Adsorption of Amino Acids, Aspartic Acid, and Lysine onto Iron-Oxide Nanoparticles. The Journal of Physical Chemistry C 2016, 120, 14372 -14381.

AMA Style

Klementina Pušnik, Mojca Peterlin, Irena Kralj Cigić, Gregor Marolt, Ksenija Kogej, Alenka Mertelj, Sašo Gyergyek, Darko Makovec. Adsorption of Amino Acids, Aspartic Acid, and Lysine onto Iron-Oxide Nanoparticles. The Journal of Physical Chemistry C. 2016; 120 (26):14372-14381.

Chicago/Turabian Style

Klementina Pušnik; Mojca Peterlin; Irena Kralj Cigić; Gregor Marolt; Ksenija Kogej; Alenka Mertelj; Sašo Gyergyek; Darko Makovec. 2016. "Adsorption of Amino Acids, Aspartic Acid, and Lysine onto Iron-Oxide Nanoparticles." The Journal of Physical Chemistry C 120, no. 26: 14372-14381.

Journal article
Published: 31 January 2016 in Heritage Science
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Background In this work we explore the chemical effects of particulate matter on paper. We exposed paper made of pure cellulose to the environment in different locations in central London, outdoors (in sheltered conditions) and indoors, for a period of up to 6 months. We monitored particulate matter (PM) deposition by counting the particles deposited every month with a scanning electron microscope. We analysed elemental composition of the deposited particles using inductively coupled plasma mass spectrometry. After accelerated degradation of the exposed samples, we determined the degree of polymerisation using viscometry. Results We observed higher deposition rates and higher metal concentration outdoors than indoors. Elemental analysis of the deposited particles revealed the presence of some transition metals (Fe, Cu, Cr) that can contribute to the degradation of cellulose fibres through the Fenton reaction. By comparing the degree of polymerisation of protected, unprotected and unexposed samples we could determine the relative contribution of PM deposition on the increase of the degradation rate. We found that the surface concentration of iron correlates with the reduction in the degree of polymerisation of the exposed paper. Conclusions The results suggest that the presence of Fenton metals in PM has a significant effect on the acceleration of the degradation of cellulose. However, we estimate that this will unlikely occur at the levels of area coverage by PM that are typically avoided in indoor heritage through preventive maintenance and cleaning. Keywords Paper PM Indoors Exposure

ACS Style

Josep Grau-Bové; Bojan Budič; Irena Kralj Cigić; David Thickett; Stefania Signorello; Matija Strlič. The effect of particulate matter on paper degradation. Heritage Science 2016, 4, 79 .

AMA Style

Josep Grau-Bové, Bojan Budič, Irena Kralj Cigić, David Thickett, Stefania Signorello, Matija Strlič. The effect of particulate matter on paper degradation. Heritage Science. 2016; 4 (1):79.

Chicago/Turabian Style

Josep Grau-Bové; Bojan Budič; Irena Kralj Cigić; David Thickett; Stefania Signorello; Matija Strlič. 2016. "The effect of particulate matter on paper degradation." Heritage Science 4, no. 1: 79.

Journal article
Published: 13 August 2015 in Molecules
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The reactivity of tocopherols with 2,2-diphenyl-1-picrylhydrazyl (DPPH) was studied in model systems in order to establish a method for quantifying vitamin E in plant oils. The method was optimized with respect to solvent composition of the assay medium, which has a large influence on the course of reaction of tocopherols with DPPH. The rate of reaction of α-tocopherol with DPPH is higher than that of γ-tocopherol in both protic and aprotic solvents. In ethyl acetate, routinely applied for the analysis of antioxidant potential (AOP) of plant oils, reactions of tocopherols with DPPH are slower and concentration of tocopherols in the assay has a large influence on their molar reactivity. In 2-propanol, however, two electrons are exchanged for both α- and γ-tocopherols, independent of their concentration. 2-propanol is not toxic and is fully compatible with polypropylene labware. The chromatographically determined content of tocopherols and their molar reactivity in the DPPH assay reveal that only tocopherols contribute to the AOP of sunflower oil, whereas the contribution of tocopherols to the AOP of linseed oil is 75%. The DPPH assay in 2-propanol can be applied for rapid and cheap estimation of vitamin E content in plant oils where tocopherols are major antioxidants.

ACS Style

Tjaša Prevc; Alenka Levart; Irena Kralj Cigić; Janez Salobir; Natasa Poklar Ulrih; Blaž Cigić. Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay. Molecules 2015, 20, 14777 -14790.

AMA Style

Tjaša Prevc, Alenka Levart, Irena Kralj Cigić, Janez Salobir, Natasa Poklar Ulrih, Blaž Cigić. Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay. Molecules. 2015; 20 (8):14777-14790.

Chicago/Turabian Style

Tjaša Prevc; Alenka Levart; Irena Kralj Cigić; Janez Salobir; Natasa Poklar Ulrih; Blaž Cigić. 2015. "Rapid Estimation of Tocopherol Content in Linseed and Sunflower Oils-Reactivity and Assay." Molecules 20, no. 8: 14777-14790.

Research article
Published: 04 April 2014 in Langmuir
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The polysaccharide levan is a homopolymer of fructose and appears in nature as an important structural component of some bacterial biofilms. This paper reports the structural and dynamic properties of aqueous solutions of levan of various origin obtained from dynamic rheological, small-angle X-ray scattering, static and dynamic light scattering, as well as density and sound velocity measurements, determination of polymer branching after per-O-methylation, and microscopy. Besides samples of commercially available levan from Zymomonas mobilis and Erwinia herbicola, we also isolated, purified, and studied a levan sample from the biofilm of Bacillus subtilis. The results of dynamic rheological and light scattering measurements revealed very interesting viscoelastic properties of levan solutions even at very low polymer concentrations. The findings were complemented by small-angle X-ray scattering data that revealed some important differences in the structure of the aqueous levan solutions at the molecular level. Besides presenting detailed dynamic and structural results on the polysaccharide systems of various levans, one of the essential goals of this work was to point out the level of structural information that may be obtained for such polymer systems by combining basic physicochemical, rheological, and various light scattering techniques.

ACS Style

Elizabeta Benigar; Iztok Dogsa; David Stopar; Andrej Jamnik; Irena Kralj Cigić; Matija Tomšič. Structure and Dynamics of a Polysaccharide Matrix: Aqueous Solutions of Bacterial Levan. Langmuir 2014, 30, 4172 -4182.

AMA Style

Elizabeta Benigar, Iztok Dogsa, David Stopar, Andrej Jamnik, Irena Kralj Cigić, Matija Tomšič. Structure and Dynamics of a Polysaccharide Matrix: Aqueous Solutions of Bacterial Levan. Langmuir. 2014; 30 (14):4172-4182.

Chicago/Turabian Style

Elizabeta Benigar; Iztok Dogsa; David Stopar; Andrej Jamnik; Irena Kralj Cigić; Matija Tomšič. 2014. "Structure and Dynamics of a Polysaccharide Matrix: Aqueous Solutions of Bacterial Levan." Langmuir 30, no. 14: 4172-4182.