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Wyszukujesz frazę "high performance liquid chromatography (HPLC)" wg kryterium: Temat


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Tytuł:
Izoflawony – struktura, aktywność biologiczna oraz metody oznaczania przy użyciu wysokosprawnej chromatografii cieczowej
Isofalvones – structure, biological activity and determination by high performance liquid chromatography
Autorzy:
Bachanek, I.
Czauderna, M.
Powiązania:
https://bibliotekanauki.pl/articles/171515.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
izoflawony
przygotowanie próbek
oznaczanie związków izoflawonowych
wysokosprawna chromatografia cieczowa
HPLC
isoflavone
sample preparation
determination
high performance liquid chromatography
Opis:
Isoflavones are a subclass of flavonoids and are also described as phytoestrogen compounds, since they exhibit estrogenic activity (similar effects to estradiol hormones). The basic characteristics of isoflavone structure is a flavone nucleus, composed of two benzene rings (A and B) linked to a heterocyclic ring C (Fig. 1). The benzene ring B position is the basis for the categorization of a flavanoid class (position 2) and a isoflavonoid class (position 3) [8]. Isoflavones are classified according to substitutions. The glucoside forms can be esterified at the 6’’-O-position of the glucose ring with malonyl or acetyl groups forming another compounds. In food and plants, flavonoids exist primarily as 3-O-glycosides and polymers [14]. Isoflavonoids are a group of chemical compounds which is widely distributed in the vegetable world. Their biological activity has found remarkable pharmaceutical, therapeutic, dietary and nutritional applications. The structure of phytoestrogens enables them to bind to the estrogen receptors (ERs), they are similar to 17β-estradiol, contain an aromatic ring with hydroxyl group and have the binding affinity to both estrogen. In addition, isoflavones interact with the metabolism of steroid hormones. Recently, they have come into focus of interest due to several reports about their positive effect on human health, in particular prevention of hormone-dependent cancers, cardiovascular diseases, osteoporosis, adverse menopausal manifestations and age-related cognitive decline. To identify the potential health benefits associated with the consumption of isoflavones, it is of critical importance to have high-quality and comprehensive data. To this end, adequate analytical methodologies are essential for a reliable and exact identification as well as for quantification. Moreover, methodologies and techniques used need to keep up with technology to improve the performance in terms of resolution, efficiency, precision, reproducibility and speed, allowing a proportionate increase in the amount and quality of information gathered [7]. Common methods for the extraction of isoflavones from soybeans and soy products include organic solvent extraction with aqueous methanol, ethanol or acetonitrile, using simple mixing, ultra-sonification or refluxing techniques [24]. The application of micro-scale and nano-scale extraction and separation techniques is the most likely future development, resulting in quick, sensitive analytical methods for sample preparation and analysis of flavonoids and their metabolites. Miniaturization, high-throughput systems utilizing new sorbents and automation of chromatographic systems are of great interest in clinical, pharmaceutical, environmental and food fields. The most used analysis technique for the quantification of isoflavones in solid samples is, with no doubt, reversed-phase HPLC using C18 based columns with water and methanol or acetonitrile containing small amounts of acid as a mobile phase [7].
Źródło:
Wiadomości Chemiczne; 2014, 68, 7-8; 661-681
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metody oznaczania barwników spożywczych
Methods for the determination of food dyes
Autorzy:
Kałwa, K.
Mazurek, A.
Powiązania:
https://bibliotekanauki.pl/articles/171756.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
barwniki spożywcze
wysokosprawna chromatografia cieczowa
HPLC
spektrofotometria
chromatografia cienkowarstwowa
TLC
elektroforeza kapilarna
food dyes
high-performance liquid chromatography
spectrophotometry
thin layer chromatography
capillary electrophoresis
Opis:
Food dyes are chemical substances that were developed to enhance the appearance of food by giving it artificial color. People have added colorings to food for centuries, but the first artificial food colorings were created in 1856 from coal tar. Over the years, hundreds of artificial food dyes have been developed, but a majority of them have since been found to be toxic. There is only a handful of artificial dyes that are still used in food. Food manufacturers often prefer artificial food dyes over natural food colorings, such as beta carotene and beet extract, because they produce a more vibrant color [1]. However, there is quite a bit of controversy regarding the safety of artificial food dyes. All of the artificial dyes that are currently used in food have gone through testing for toxicity in animal studies. Regulatory agencies, like the US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA), have concluded that the dyes do not pose significant health risks. Not everyone agrees with that conclusion. Interestingly, some food dyes are deemed safe in one country, but banned from human consumption in another, making it extremely confusing to assess their safety [2]. Undesirable effects of azo dyes used for coloring food products led to the development of very sensitive and selective analytical methods successfully used for their determination in various food matrices. Many different methods have been employed for the determination of synthetic dyes in food and beverages including thin layer chromatography and capillary electrophoresis [3]. However, these methods can be time consuming and may not be applicable for the simultaneous analysis of many dyes. Conventional HPLC methods have been employed for the analysis of synthetic colorants and while useful, these methods require long analysis times and large amounts of expensive solvents [4, 5]. Preparation of the test sample involves the use of various techniques such as membrane filtration due to the complexity of food products. Therefore, the development of simple, selective extraction methods together with the combination of chromatographic and spectrophotometric techniques are of great importance [6]. One of the most difficult stages of the analysis is the appropriate selection of the method for the determination of food colors. In the case of spectrophotometric methods, the main advantage is the low cost of the determination, however, the lack of specificity of the absorption spectrum usually makes it difficult to apply this method in the case of a mixture of different absorbing dyes due to the overlap of the spectra. The CE (Capillary Electrophoresis) analysis is faster and more economical compared to conventional electrophoresis and chromatography. The production of cheap capillaries and the development of on-line detection systems contributed to the development of modern capillary electrophoresis. Capillary electrophoresis has a number of types of separation. Ultimately, it is impossible to determine the one particular appropriate specific method for the determination of food dyes due to their diverse structure and chemical composition [4, 7].
Źródło:
Wiadomości Chemiczne; 2018, 72, 9-10; 667-683
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chromatograficzne metody oznaczania parabenów w próbkach środowiskowych i kosmetykach. Cz. 2
Autorzy:
Kozarska, A.
Krzyżewska, I.
Powiązania:
https://bibliotekanauki.pl/articles/273853.pdf
Data publikacji:
2017
Wydawca:
Roble
Tematy:
wysokosprawna chromatografia cieczowa
HPLC
parabeny
kosmetyki
próbki środowiskowe
elektroforeza
chromatografia gazowa
GC
oznaczanie parabenów
high-performance liquid chromatography
parabens
cosmetics
environmental samples
electrophoresis
gas chromatography
parabens determination
Źródło:
LAB Laboratoria, Aparatura, Badania; 2017, 22, 2; 6-12
1427-5619
Pojawia się w:
LAB Laboratoria, Aparatura, Badania
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of Aldehydes in Wet Deposition
Oznaczanie aldehydów w depozycji mokrej
Autorzy:
Czaplicka, M.
Jaworek, K.
Wochnik, A.
Powiązania:
https://bibliotekanauki.pl/articles/204596.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aldehydes
wet deposition
derivatization
SPE
solid-phase extraction
HPLC
high performance liquid chromatography
aldehydy
mokra depozycja
derywatyzacja
ekstrakcja w fazie stałej
wysokosprawna chromatografia cieczowa
Opis:
The paper presents two sample preparation procedures for the determination of aldehydes in wet deposition. In both cases the 2,4-dinitrophenylhydrazine derivatization and solid phase extraction were applied. The derivatization in method A was applied before the extraction, the extraction in method B was carried out with simultaneous derivatisation. Accuracy of both methods was evaluated on the basis of the analysis of aqueous solutions of selected carbonyl compounds. Both methods were characterized by good recovery, however, due to the precision of the method expressed as RSD for testing of environmental samples the method B was used. The analysis of environmental samples showed significant differences in the concentrations of aldehydes in wet deposition, depending on the location of the sampling point. In the case of samples taken from agricultural areas the predominant aldehydes were formaldehyde and acetaldehyde. Formaldehyde was from 31% to 47% of the determined compounds. While in samples collected near a traffic source, in the deposition acrolein was determined at the levels from 62% to 64% of the identified compounds.
W pracy przedstawiono dwie procedury przygotowania próbek mokrej depozycji do oznaczeń aldehydów. W obydwóch przypadkach zastosowano derywatyzację 2,4-dinitrofenylohydrazyną oraz ekstrakcję do fazy stałej. W metodzie A derywatyzacja poprzedzała ekstrakcję, w metodzie B ekstrakcję prowadzono z równoczesną derywatyzacją. Na podstawie analiz wodnych roztworów wybranych związków karbonylowych oceniono precyzję obydwóch metod. Ze względu na odzysk oraz wartość względnego odchylenia do analiz próbek środowiskowych pobranych z obszarów silnie uprzemysłowionych i rolniczych wybrano metodę B. Analiza próbek środowiskowych wykazała znaczne zróżnicowanie stężeń aldehydów w mokrej depozycji w zależności od lokalizacji punktu pobierania próbek. W przypadku próbek pobranych z obszarów rolniczych dominującymi aldehydami były formaldehyd i acetaldehyd. Formaldehyd stanowił od 31% do 47% oznaczonych związków. Podczas gdy w próbkach pobranych w pobliżu źródeł komunikacyjnych w depozycji stwierdzono udział akroleiny w oznaczonych aldehydach na poziomie od 62% do 64% oznaczonych związków.
Źródło:
Archives of Environmental Protection; 2014, 40, 2; 21-31
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie oddziaływania wankomycyny z fragmentem peptydoglikanu ściany komórkowej bakterii
Study on interaction of vancomycin with bacterial cell wall peptidoglycan
Autorzy:
Samaszko-Fiertek, J.
Ślusarz, R.
Madaj, J.
Powiązania:
https://bibliotekanauki.pl/articles/172720.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wankomycyna
wysokosprawna chromatografia cieczowa
HPLC
elektroforeza kapilarna
magnetyczny rezonans jądrowy
NMR
SAMs
vancomycin
high performance liquid chromatography
capillary electrophoresis
nuclear magnetic resonance (NMR)
self-assembled monolayers
Opis:
Unfortunately, despite of work involved in understanding of the mechanism of bacterial virulence, especially Staphylococcus aureus, it has not been developed effective therapy against this bacteria. The first antibiotic used against this bacteria was penicillin, which was discovered by Alexander Fleming in 1928. A new generation of drugs introduced into therapy against Staphylococcus aureus and other Gram-positive bacteria are glycopeptide antibiotics. The most widespread and most commonly used are vancomycin and teicoplanin, discovered respectively in 1956 and 1978. As a result of frequent use of vancomycin VISA (ang. Vancomycin-intermediate Staphylococcus aureus) and VRSA (ang. Vancomycin-resistant Staphylococcus aureus) strains were discovered. The mechanism of action of this antibiotic based on the inhibition of the biosynthesis of bacterial cell wall peptidoglycan fragment. Forming stabilized by hydrogen bonds complex with terminal fragment of peptidoglycan (dipeptide d-Ala-d-Ala) vancomycin prevents its further crosslinking [2] (Fig. 1). However, in recent years other theories of the mechanism of action of glycopeptide antibiotics against Gram-positive bacteria were presented it seems to be crucial to find methods of selection of new antibiotics and for this purpose standard techniques of the analysis, including isothermal titration calorimetry (ITC) [3], nuclear magnetic resonance spectroscopy (NMR) [8–15], high performance liquid chromatography (HPLC) [16], capillary electrophoresis [17] or self-assembled monolayers (SAMs) [22] are used. Discovering new methods for studying of interaction between vancomycin and Gram-positive bacterial cell wall allows use it as a new technique for rapid selection of potential new antibiotics, including glycopeptide derivatives.
Źródło:
Wiadomości Chemiczne; 2015, 69, 7-8; 491-511
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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