Jan Teipel - Academia.edu (original) (raw)

Papers by Jan Teipel

Chemistry

Highly reactive decomposition products of deuterated chloroform can deteriorate samples dissolved... more Highly reactive decomposition products of deuterated chloroform can deteriorate samples dissolved in this commonly used solvent for nuclear magnetic resonance (NMR) spectroscopy. Samples for metabolomics studies often contain a complex mixture of sensitive substances such as phospholipids, peptides, unsaturated fatty acids or vitamins. If these react with decomposition products (of chloroform), abnormal NMR spectra could result, e.g., signal shifts depending on pH, attenuation of signals over time due to chemical changes of analytes or new signals from reaction products. Such irreproducibly influenced spectra are especially problematic for non-targeted analysis methods using automated chemometrical data evaluation. To prevent these artefacts, chlorine, phosgene and hydrochloric acid need to be eliminated from deuterated chloroform before its use. Since the common stabilisation methods have proven to be insufficient for sensitive NMR samples, another purging method has been tested: M...

Für einen effizienten Verbraucherschutz hat das CVUA Karlsruhe ein ressourcenschonendes Screening... more Für einen effizienten Verbraucherschutz hat das CVUA Karlsruhe ein ressourcenschonendes Screening-Verfahren auf Basis der quantitativen Nuclear-Magnetic -Resonance-Spektrometrie (qNMR) etabliert, welches in einem Analysengang elf verschiedene wertgebende Bestandteile von Erfrischungsgetränken bestimmen kann. Aufbauend auf dieser Methode wurde vom CVUA-OWL das Spektrum auf zurzeit 31 Analyten erweitert und für verschiedene Getränkearten validiert.

Hanfhaltige Lebensmittel liegen voll im Trend. Großer Popularität erfreuen sich derzeit neuartige... more Hanfhaltige Lebensmittel liegen voll im Trend. Großer Popularität erfreuen sich derzeit neuartige Nahrungsergänzungsmittel mit Cannabisextrakt, für die vor allem mit dem nicht-psychotropen Cannabinoid Cannabidiol (CBD) und dessen vermeintlich positiven Wirkungen auf die Gesundheit geworben wird. Seit dem Aufkommen dieser CBD-Produkte werden durch die Lebensmittelüberwachungsbehörden extrem überhöhte ∆9 -Tetrahydrocannabinol (THC)-Gehalte berichtet, die von klassischen Hanflebensmitteln nie erreicht wurden. Die Anwesenheit von THC in hanfbasierten Lebensmitteln hat neben der Problematik möglicher psychotroper Effekte auch Bedenken aufgeworfen, dass bei Drogentests positive Ergebnisse erhalten werden. Cannabis-positive Ergebnisse bei Blut- bzw. Urinuntersuchungen wurden bislang als ein Hinweis auf die Aufnahme von Cannabis, in der Form von Haschisch oder Marihuana, interpretiert und können daher unangenehme Folgen für den Betroffenen haben. In ersten Studien nach Aufkommen der Hanfleb...

Molecules, 2021

Phenolic structures are of great interest due to their antioxidant properties and various postula... more Phenolic structures are of great interest due to their antioxidant properties and various postulated benefits on human health. However, the quantification of these structures in fruits and vegetables, as well as in vivo or in vitro experiments, is demanding, as relevant concentrations are often low, causing problems in exactly weighing the respective amounts. Nevertheless, the determination of used concentrations is often a prerequisite for accurate results. A possibility to quantify polyphenol is the use of UV/vis spectroscopy. Therefore, the absorption coefficients of selected phenolic structures were determined in three different solvents relevant for polyphenol research (water/methanol (50/50, v/v), water, and phosphate buffer at pH 7.5). To confirm the values based on weight and to avoid errors due to impurities, hygroscopic effects, and inadequate balance care, the mass concentrations were additionally determined by quantitative NMR (q-NMR). The coefficients presented in this ...

The food additive sorbic acid is considered as an effective preservative for certain cereal produ... more The food additive sorbic acid is considered as an effective preservative for certain cereal products, and propionic acid is commonly added in bakery wares, e.g. bread and fine bakery wares. The aim of this study is to develop and validate a new nuclear magnetic resonance spectroscopy (¹H NMR) method for routine screening and quantification of sorbic and propionic acids in bread and several bakery products for quality control purposes. Results showed that none of the screened samples contained higher concentrations than regulatory maximum limits. However, for some samples, labelling of preservatives was lacking or they were used in food categories, for which the use is not approved. It can be concluded that the developed NMR method can be used for routine screening of bakery products.

Foods, 2020

Due to legal regulations, the rise of globalised (online) commerce and the need for public health... more Due to legal regulations, the rise of globalised (online) commerce and the need for public health protection, the analysis of spirit drinks (alcoholic beverages >15% vol) is a task with growing importance for governmental and commercial laboratories. In this article a newly developed method using nuclear magnetic resonance (NMR) spectroscopy for the simultaneous determination of 15 substances relevant to assessing the quality and authenticity of spirit drinks is described. The new method starts with a simple and rapid sample preparation and does not need an internal standard. For each sample, a group of 1H-NMR spectra is recorded, among them a two-dimensional spectrum for analyte identification and one-dimensional spectra with suppression of solvent signals for quantification. Using the Pulse Length Based Concentration Determination (PULCON) method, concentrations are calculated from curve fits of the characteristic signals for each analyte. The optimisation of the spectra, their...

Journal of AOAC INTERNATIONAL, 2020

Background Coffee is a popular beverage with two species, Coffea canephora and C. arabica, being ... more Background Coffee is a popular beverage with two species, Coffea canephora and C. arabica, being commercially exploited. The quality and commercial value of coffee is dependent on species and processing. C. arabica typically obtains a higher price on the market compared to C. canephora. Coffee beans undergo roasting during processing, resulting in the formation of flavor compounds including furfuryl alcohol which has been classified by the International Agency for Research on Cancer as possibly carcinogenic to humans (Group 2B). Objective The aim of this study was to identify coffee species and other properties using nuclear magnetic resonance (NMR) spectroscopy, specifically to conduct quantification of the roasting process contaminant furfuryl alcohol. Method The quantification of furfuryl alcohol was performed from the NMR spectra using the pulse length-based concentration (PULCON) methodology. Prior to NMR analysis, samples were extracted using deuterated chloroform. Results Roa...

Monitoring coffee quality as a means of detecting and preventing economically motivated fraud is ... more Monitoring coffee quality as a means of detecting and preventing economically motivated fraud is an important aspect of international commerce today. Therefore, there is a compelling need for rapid high throughput validated analytical techniques such as quantitative proton NMR spectroscopy for screening and authenticity testing. For this reason, we sought to validate an NMR spectroscopic method for routine screening of coffee for quality and authenticity. A factorial experimental design was used to investigate the influence of NMR device, extraction time and nature of coffee on the content of caffeine, 16-O-methylcafestol (OMC), kahweol, furfuryl alcohol and 5-hydroxymethylfurfural (HMF) in coffee. The method was successfully validated for specificity, selectivity, sensitivity and linearity of detector response. The proposed method produced satisfactory precision for all analytes in roasted coffee, except for kahweol in canephora (robusta) coffee. The proposed validated method may b...

Journal of Pharmaceutical and Biomedical Analysis, 2019

Ключевые слова: экологическая безопасность, биологически активный комплекс растительного происхож... more Ключевые слова: экологическая безопасность, биологически активный комплекс растительного происхождения, рост, мясо бройлеров, тяжелые металлы. Исследования посвящены изучению проблем и путей получения экологически безопасного мяса бройлеров в условиях техногенной агроэкосферы. Работа выполнена на базе птицеводческого комплекса (Челябинская область, Россия); состояла из двух этапов. На первом этапе определено содержание химических элементов в пробах почвы, воды и комбикорма, на втором этапе-апробирован способ снижения токсичных элементов в мясе птицы. Для этого из цыплята-бройлеров кросса «Смена 2», подобранных по методу аналогов, сформировано 4 группы. Первая группа (контрольная), вторая, третья и четвертая-опытные, получали с 5 суточного возраста до убоя с основным рационом биологически активный комплекс растительного происхождения, полученный из экстракта люцерны, в дозе 15, 30 и 60 мг/кг живой массы, соответственно. При применении комплекса растительного происхождения произошло перераспределение биогенных и токсичных элементов в печени бройлеров, с повышением дозы увеличилось количество биогенных элементов меди, цинка, кобальта, марганца в среднем в 1,42; 1,5; 3,43 и 1,92 раза, снизился уровень никеля и свинца в среднем в 2,37 и 2,45 раза. В результате применения биологически активного комплекса растительного происхождения отмечено, что с повышением его дозы содержание токсичных элементов (свинца и никеля) в мясе бройлеров снижается по сравнению с контролем в 1,19-1,46 и 1,89-1,92 раза. Результаты исследований определяют возможность апробирования биологически активного комплекса растительного происхождения для снижения уровня токсичных элементов в составе продукции, получаемой от других сельскохозяйственных животных.

The three heat-induced coffee contaminants acrylamide, furfuryl alcohol (FA) and 5-hydroxymethylf... more The three heat-induced coffee contaminants acrylamide, furfuryl alcohol (FA) and 5-hydroxymethylfurfural (HMF) were analyzed in a collective of commercial samples as well as in Coffea arabica seeds roasted under controlled conditions from very light Scandinavian style to very dark Neapolitan style profiles. Regarding acrylamide, average contents in commercial samples were lower than in a previous study in 2002 (196 compared to 303 µg/kg). The roasting experiment confirmed the inverse relationship between roasting degree and acrylamide content, i.e. the lighter the coffee the higher the acrylamide content. However, FA and HMF were inversely related to acrylamide and found in higher contents in darker roasts. Therefore, mitigation measures must consider all contaminants and not be focused isolatedly on acrylamide, specifically since FA and HMF are contained in much higher contents with lower margins of exposure compared to acrylamide.

Highly reactive decomposition products of (deuterated) chloroform can deteriorate samples dissolv... more Highly reactive decomposition products of (deuterated) chloroform can deteriorate samples dissolved in this commonly used NMR solvent. For sensitive samples (such as peptides, unsaturated fatty acids, vitamins), this can lead to abnormal NMR spectra (e.g. signal shifts depending on pH, attenuation of signals over time due to chemical changes of analytes, new signals from reaction products). Such irreproducibly influenced spectra are especially problematic for non-targeted analysis methods. To prevent these artefacts, chlorine, phosgene and hydrochloric acid need to be eliminated from deuterated chloroform prior to its use. Since the common stabilization methods have proven insufficient for sensitive NMR samples, another purging method has been tested: Mitigation is easily and reliably achieved by washing the deuterated chloroform with concentrated Na2CO3-solution and subsequent desiccation with oven-dried Na2CO3.

Chemistry

Highly reactive decomposition products of deuterated chloroform can deteriorate samples dissolved... more Highly reactive decomposition products of deuterated chloroform can deteriorate samples dissolved in this commonly used solvent for nuclear magnetic resonance (NMR) spectroscopy. Samples for metabolomics studies often contain a complex mixture of sensitive substances such as phospholipids, peptides, unsaturated fatty acids or vitamins. If these react with decomposition products (of chloroform), abnormal NMR spectra could result, e.g., signal shifts depending on pH, attenuation of signals over time due to chemical changes of analytes or new signals from reaction products. Such irreproducibly influenced spectra are especially problematic for non-targeted analysis methods using automated chemometrical data evaluation. To prevent these artefacts, chlorine, phosgene and hydrochloric acid need to be eliminated from deuterated chloroform before its use. Since the common stabilisation methods have proven to be insufficient for sensitive NMR samples, another purging method has been tested: M...

Für einen effizienten Verbraucherschutz hat das CVUA Karlsruhe ein ressourcenschonendes Screening... more Für einen effizienten Verbraucherschutz hat das CVUA Karlsruhe ein ressourcenschonendes Screening-Verfahren auf Basis der quantitativen Nuclear-Magnetic -Resonance-Spektrometrie (qNMR) etabliert, welches in einem Analysengang elf verschiedene wertgebende Bestandteile von Erfrischungsgetränken bestimmen kann. Aufbauend auf dieser Methode wurde vom CVUA-OWL das Spektrum auf zurzeit 31 Analyten erweitert und für verschiedene Getränkearten validiert.

Hanfhaltige Lebensmittel liegen voll im Trend. Großer Popularität erfreuen sich derzeit neuartige... more Hanfhaltige Lebensmittel liegen voll im Trend. Großer Popularität erfreuen sich derzeit neuartige Nahrungsergänzungsmittel mit Cannabisextrakt, für die vor allem mit dem nicht-psychotropen Cannabinoid Cannabidiol (CBD) und dessen vermeintlich positiven Wirkungen auf die Gesundheit geworben wird. Seit dem Aufkommen dieser CBD-Produkte werden durch die Lebensmittelüberwachungsbehörden extrem überhöhte ∆9 -Tetrahydrocannabinol (THC)-Gehalte berichtet, die von klassischen Hanflebensmitteln nie erreicht wurden. Die Anwesenheit von THC in hanfbasierten Lebensmitteln hat neben der Problematik möglicher psychotroper Effekte auch Bedenken aufgeworfen, dass bei Drogentests positive Ergebnisse erhalten werden. Cannabis-positive Ergebnisse bei Blut- bzw. Urinuntersuchungen wurden bislang als ein Hinweis auf die Aufnahme von Cannabis, in der Form von Haschisch oder Marihuana, interpretiert und können daher unangenehme Folgen für den Betroffenen haben. In ersten Studien nach Aufkommen der Hanfleb...

Molecules, 2021

Phenolic structures are of great interest due to their antioxidant properties and various postula... more Phenolic structures are of great interest due to their antioxidant properties and various postulated benefits on human health. However, the quantification of these structures in fruits and vegetables, as well as in vivo or in vitro experiments, is demanding, as relevant concentrations are often low, causing problems in exactly weighing the respective amounts. Nevertheless, the determination of used concentrations is often a prerequisite for accurate results. A possibility to quantify polyphenol is the use of UV/vis spectroscopy. Therefore, the absorption coefficients of selected phenolic structures were determined in three different solvents relevant for polyphenol research (water/methanol (50/50, v/v), water, and phosphate buffer at pH 7.5). To confirm the values based on weight and to avoid errors due to impurities, hygroscopic effects, and inadequate balance care, the mass concentrations were additionally determined by quantitative NMR (q-NMR). The coefficients presented in this ...

The food additive sorbic acid is considered as an effective preservative for certain cereal produ... more The food additive sorbic acid is considered as an effective preservative for certain cereal products, and propionic acid is commonly added in bakery wares, e.g. bread and fine bakery wares. The aim of this study is to develop and validate a new nuclear magnetic resonance spectroscopy (¹H NMR) method for routine screening and quantification of sorbic and propionic acids in bread and several bakery products for quality control purposes. Results showed that none of the screened samples contained higher concentrations than regulatory maximum limits. However, for some samples, labelling of preservatives was lacking or they were used in food categories, for which the use is not approved. It can be concluded that the developed NMR method can be used for routine screening of bakery products.

Foods, 2020

Due to legal regulations, the rise of globalised (online) commerce and the need for public health... more Due to legal regulations, the rise of globalised (online) commerce and the need for public health protection, the analysis of spirit drinks (alcoholic beverages >15% vol) is a task with growing importance for governmental and commercial laboratories. In this article a newly developed method using nuclear magnetic resonance (NMR) spectroscopy for the simultaneous determination of 15 substances relevant to assessing the quality and authenticity of spirit drinks is described. The new method starts with a simple and rapid sample preparation and does not need an internal standard. For each sample, a group of 1H-NMR spectra is recorded, among them a two-dimensional spectrum for analyte identification and one-dimensional spectra with suppression of solvent signals for quantification. Using the Pulse Length Based Concentration Determination (PULCON) method, concentrations are calculated from curve fits of the characteristic signals for each analyte. The optimisation of the spectra, their...

Journal of AOAC INTERNATIONAL, 2020

Background Coffee is a popular beverage with two species, Coffea canephora and C. arabica, being ... more Background Coffee is a popular beverage with two species, Coffea canephora and C. arabica, being commercially exploited. The quality and commercial value of coffee is dependent on species and processing. C. arabica typically obtains a higher price on the market compared to C. canephora. Coffee beans undergo roasting during processing, resulting in the formation of flavor compounds including furfuryl alcohol which has been classified by the International Agency for Research on Cancer as possibly carcinogenic to humans (Group 2B). Objective The aim of this study was to identify coffee species and other properties using nuclear magnetic resonance (NMR) spectroscopy, specifically to conduct quantification of the roasting process contaminant furfuryl alcohol. Method The quantification of furfuryl alcohol was performed from the NMR spectra using the pulse length-based concentration (PULCON) methodology. Prior to NMR analysis, samples were extracted using deuterated chloroform. Results Roa...

Monitoring coffee quality as a means of detecting and preventing economically motivated fraud is ... more Monitoring coffee quality as a means of detecting and preventing economically motivated fraud is an important aspect of international commerce today. Therefore, there is a compelling need for rapid high throughput validated analytical techniques such as quantitative proton NMR spectroscopy for screening and authenticity testing. For this reason, we sought to validate an NMR spectroscopic method for routine screening of coffee for quality and authenticity. A factorial experimental design was used to investigate the influence of NMR device, extraction time and nature of coffee on the content of caffeine, 16-O-methylcafestol (OMC), kahweol, furfuryl alcohol and 5-hydroxymethylfurfural (HMF) in coffee. The method was successfully validated for specificity, selectivity, sensitivity and linearity of detector response. The proposed method produced satisfactory precision for all analytes in roasted coffee, except for kahweol in canephora (robusta) coffee. The proposed validated method may b...

Journal of Pharmaceutical and Biomedical Analysis, 2019

Ключевые слова: экологическая безопасность, биологически активный комплекс растительного происхож... more Ключевые слова: экологическая безопасность, биологически активный комплекс растительного происхождения, рост, мясо бройлеров, тяжелые металлы. Исследования посвящены изучению проблем и путей получения экологически безопасного мяса бройлеров в условиях техногенной агроэкосферы. Работа выполнена на базе птицеводческого комплекса (Челябинская область, Россия); состояла из двух этапов. На первом этапе определено содержание химических элементов в пробах почвы, воды и комбикорма, на втором этапе-апробирован способ снижения токсичных элементов в мясе птицы. Для этого из цыплята-бройлеров кросса «Смена 2», подобранных по методу аналогов, сформировано 4 группы. Первая группа (контрольная), вторая, третья и четвертая-опытные, получали с 5 суточного возраста до убоя с основным рационом биологически активный комплекс растительного происхождения, полученный из экстракта люцерны, в дозе 15, 30 и 60 мг/кг живой массы, соответственно. При применении комплекса растительного происхождения произошло перераспределение биогенных и токсичных элементов в печени бройлеров, с повышением дозы увеличилось количество биогенных элементов меди, цинка, кобальта, марганца в среднем в 1,42; 1,5; 3,43 и 1,92 раза, снизился уровень никеля и свинца в среднем в 2,37 и 2,45 раза. В результате применения биологически активного комплекса растительного происхождения отмечено, что с повышением его дозы содержание токсичных элементов (свинца и никеля) в мясе бройлеров снижается по сравнению с контролем в 1,19-1,46 и 1,89-1,92 раза. Результаты исследований определяют возможность апробирования биологически активного комплекса растительного происхождения для снижения уровня токсичных элементов в составе продукции, получаемой от других сельскохозяйственных животных.

The three heat-induced coffee contaminants acrylamide, furfuryl alcohol (FA) and 5-hydroxymethylf... more The three heat-induced coffee contaminants acrylamide, furfuryl alcohol (FA) and 5-hydroxymethylfurfural (HMF) were analyzed in a collective of commercial samples as well as in Coffea arabica seeds roasted under controlled conditions from very light Scandinavian style to very dark Neapolitan style profiles. Regarding acrylamide, average contents in commercial samples were lower than in a previous study in 2002 (196 compared to 303 µg/kg). The roasting experiment confirmed the inverse relationship between roasting degree and acrylamide content, i.e. the lighter the coffee the higher the acrylamide content. However, FA and HMF were inversely related to acrylamide and found in higher contents in darker roasts. Therefore, mitigation measures must consider all contaminants and not be focused isolatedly on acrylamide, specifically since FA and HMF are contained in much higher contents with lower margins of exposure compared to acrylamide.

Highly reactive decomposition products of (deuterated) chloroform can deteriorate samples dissolv... more Highly reactive decomposition products of (deuterated) chloroform can deteriorate samples dissolved in this commonly used NMR solvent. For sensitive samples (such as peptides, unsaturated fatty acids, vitamins), this can lead to abnormal NMR spectra (e.g. signal shifts depending on pH, attenuation of signals over time due to chemical changes of analytes, new signals from reaction products). Such irreproducibly influenced spectra are especially problematic for non-targeted analysis methods. To prevent these artefacts, chlorine, phosgene and hydrochloric acid need to be eliminated from deuterated chloroform prior to its use. Since the common stabilization methods have proven insufficient for sensitive NMR samples, another purging method has been tested: Mitigation is easily and reliably achieved by washing the deuterated chloroform with concentrated Na2CO3-solution and subsequent desiccation with oven-dried Na2CO3.